Adding upstream version 5.10.209.upstream/5.10.209

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

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+.. SPDX-License-Identifier: GPL-2.0
+
+===================================
+Linux Ethernet Bonding Driver HOWTO
+===================================
+
+Latest update: 27 April 2011
+
+Initial release: Thomas Davis <tadavis at lbl.gov>
+
+Corrections, HA extensions: 2000/10/03-15:
+
+  - Willy Tarreau <willy at meta-x.org>
+  - Constantine Gavrilov <const-g at xpert.com>
+  - Chad N. Tindel <ctindel at ieee dot org>
+  - Janice Girouard <girouard at us dot ibm dot com>
+  - Jay Vosburgh <fubar at us dot ibm dot com>
+
+Reorganized and updated Feb 2005 by Jay Vosburgh
+Added Sysfs information: 2006/04/24
+
+  - Mitch Williams <mitch.a.williams at intel.com>
+
+Introduction
+============
+
+The Linux bonding driver provides a method for aggregating
+multiple network interfaces into a single logical "bonded" interface.
+The behavior of the bonded interfaces depends upon the mode; generally
+speaking, modes provide either hot standby or load balancing services.
+Additionally, link integrity monitoring may be performed.
+
+The bonding driver originally came from Donald Becker's
+beowulf patches for kernel 2.0. It has changed quite a bit since, and
+the original tools from extreme-linux and beowulf sites will not work
+with this version of the driver.
+
+For new versions of the driver, updated userspace tools, and
+who to ask for help, please follow the links at the end of this file.
+
+.. Table of Contents
+
+   1. Bonding Driver Installation
+
+   2. Bonding Driver Options
+
+   3. Configuring Bonding Devices
+   3.1	Configuration with Sysconfig Support
+   3.1.1		Using DHCP with Sysconfig
+   3.1.2		Configuring Multiple Bonds with Sysconfig
+   3.2	Configuration with Initscripts Support
+   3.2.1		Using DHCP with Initscripts
+   3.2.2		Configuring Multiple Bonds with Initscripts
+   3.3	Configuring Bonding Manually with Ifenslave
+   3.3.1		Configuring Multiple Bonds Manually
+   3.4	Configuring Bonding Manually via Sysfs
+   3.5	Configuration with Interfaces Support
+   3.6	Overriding Configuration for Special Cases
+   3.7 Configuring LACP for 802.3ad mode in a more secure way
+
+   4. Querying Bonding Configuration
+   4.1	Bonding Configuration
+   4.2	Network Configuration
+
+   5. Switch Configuration
+
+   6. 802.1q VLAN Support
+
+   7. Link Monitoring
+   7.1	ARP Monitor Operation
+   7.2	Configuring Multiple ARP Targets
+   7.3	MII Monitor Operation
+
+   8. Potential Trouble Sources
+   8.1	Adventures in Routing
+   8.2	Ethernet Device Renaming
+   8.3	Painfully Slow Or No Failed Link Detection By Miimon
+
+   9. SNMP agents
+
+   10. Promiscuous mode
+
+   11. Configuring Bonding for High Availability
+   11.1	High Availability in a Single Switch Topology
+   11.2	High Availability in a Multiple Switch Topology
+   11.2.1		HA Bonding Mode Selection for Multiple Switch Topology
+   11.2.2		HA Link Monitoring for Multiple Switch Topology
+
+   12. Configuring Bonding for Maximum Throughput
+   12.1	Maximum Throughput in a Single Switch Topology
+   12.1.1		MT Bonding Mode Selection for Single Switch Topology
+   12.1.2		MT Link Monitoring for Single Switch Topology
+   12.2	Maximum Throughput in a Multiple Switch Topology
+   12.2.1		MT Bonding Mode Selection for Multiple Switch Topology
+   12.2.2		MT Link Monitoring for Multiple Switch Topology
+
+   13. Switch Behavior Issues
+   13.1	Link Establishment and Failover Delays
+   13.2	Duplicated Incoming Packets
+
+   14. Hardware Specific Considerations
+   14.1	IBM BladeCenter
+
+   15. Frequently Asked Questions
+
+   16. Resources and Links
+
+
+1. Bonding Driver Installation
+==============================
+
+Most popular distro kernels ship with the bonding driver
+already available as a module. If your distro does not, or you
+have need to compile bonding from source (e.g., configuring and
+installing a mainline kernel from kernel.org), you'll need to perform
+the following steps:
+
+1.1 Configure and build the kernel with bonding
+-----------------------------------------------
+
+The current version of the bonding driver is available in the
+drivers/net/bonding subdirectory of the most recent kernel source
+(which is available on http://kernel.org).  Most users "rolling their
+own" will want to use the most recent kernel from kernel.org.
+
+Configure kernel with "make menuconfig" (or "make xconfig" or
+"make config"), then select "Bonding driver support" in the "Network
+device support" section.  It is recommended that you configure the
+driver as module since it is currently the only way to pass parameters
+to the driver or configure more than one bonding device.
+
+Build and install the new kernel and modules.
+
+1.2 Bonding Control Utility
+---------------------------
+
+It is recommended to configure bonding via iproute2 (netlink)
+or sysfs, the old ifenslave control utility is obsolete.
+
+2. Bonding Driver Options
+=========================
+
+Options for the bonding driver are supplied as parameters to the
+bonding module at load time, or are specified via sysfs.
+
+Module options may be given as command line arguments to the
+insmod or modprobe command, but are usually specified in either the
+``/etc/modprobe.d/*.conf`` configuration files, or in a distro-specific
+configuration file (some of which are detailed in the next section).
+
+Details on bonding support for sysfs is provided in the
+"Configuring Bonding Manually via Sysfs" section, below.
+
+The available bonding driver parameters are listed below. If a
+parameter is not specified the default value is used.  When initially
+configuring a bond, it is recommended "tail -f /var/log/messages" be
+run in a separate window to watch for bonding driver error messages.
+
+It is critical that either the miimon or arp_interval and
+arp_ip_target parameters be specified, otherwise serious network
+degradation will occur during link failures.  Very few devices do not
+support at least miimon, so there is really no reason not to use it.
+
+Options with textual values will accept either the text name
+or, for backwards compatibility, the option value.  E.g.,
+"mode=802.3ad" and "mode=4" set the same mode.
+
+The parameters are as follows:
+
+active_slave
+
+	Specifies the new active slave for modes that support it
+	(active-backup, balance-alb and balance-tlb).  Possible values
+	are the name of any currently enslaved interface, or an empty
+	string.  If a name is given, the slave and its link must be up in order
+	to be selected as the new active slave.  If an empty string is
+	specified, the current active slave is cleared, and a new active
+	slave is selected automatically.
+
+	Note that this is only available through the sysfs interface. No module
+	parameter by this name exists.
+
+	The normal value of this option is the name of the currently
+	active slave, or the empty string if there is no active slave or
+	the current mode does not use an active slave.
+
+ad_actor_sys_prio
+
+	In an AD system, this specifies the system priority. The allowed range
+	is 1 - 65535. If the value is not specified, it takes 65535 as the
+	default value.
+
+	This parameter has effect only in 802.3ad mode and is available through
+	SysFs interface.
+
+ad_actor_system
+
+	In an AD system, this specifies the mac-address for the actor in
+	protocol packet exchanges (LACPDUs). The value cannot be a multicast
+	address. If the all-zeroes MAC is specified, bonding will internally
+	use the MAC of the bond itself. It is preferred to have the
+	local-admin bit set for this mac but driver does not enforce it. If
+	the value is not given then system defaults to using the masters'
+	mac address as actors' system address.
+
+	This parameter has effect only in 802.3ad mode and is available through
+	SysFs interface.
+
+ad_select
+
+	Specifies the 802.3ad aggregation selection logic to use.  The
+	possible values and their effects are:
+
+	stable or 0
+
+		The active aggregator is chosen by largest aggregate
+		bandwidth.
+
+		Reselection of the active aggregator occurs only when all
+		slaves of the active aggregator are down or the active
+		aggregator has no slaves.
+
+		This is the default value.
+
+	bandwidth or 1
+
+		The active aggregator is chosen by largest aggregate
+		bandwidth.  Reselection occurs if:
+
+		- A slave is added to or removed from the bond
+
+		- Any slave's link state changes
+
+		- Any slave's 802.3ad association state changes
+
+		- The bond's administrative state changes to up
+
+	count or 2
+
+		The active aggregator is chosen by the largest number of
+		ports (slaves).  Reselection occurs as described under the
+		"bandwidth" setting, above.
+
+	The bandwidth and count selection policies permit failover of
+	802.3ad aggregations when partial failure of the active aggregator
+	occurs.  This keeps the aggregator with the highest availability
+	(either in bandwidth or in number of ports) active at all times.
+
+	This option was added in bonding version 3.4.0.
+
+ad_user_port_key
+
+	In an AD system, the port-key has three parts as shown below -
+
+	   =====  ============
+	   Bits   Use
+	   =====  ============
+	   00     Duplex
+	   01-05  Speed
+	   06-15  User-defined
+	   =====  ============
+
+	This defines the upper 10 bits of the port key. The values can be
+	from 0 - 1023. If not given, the system defaults to 0.
+
+	This parameter has effect only in 802.3ad mode and is available through
+	SysFs interface.
+
+all_slaves_active
+
+	Specifies that duplicate frames (received on inactive ports) should be
+	dropped (0) or delivered (1).
+
+	Normally, bonding will drop duplicate frames (received on inactive
+	ports), which is desirable for most users. But there are some times
+	it is nice to allow duplicate frames to be delivered.
+
+	The default value is 0 (drop duplicate frames received on inactive
+	ports).
+
+arp_interval
+
+	Specifies the ARP link monitoring frequency in milliseconds.
+
+	The ARP monitor works by periodically checking the slave
+	devices to determine whether they have sent or received
+	traffic recently (the precise criteria depends upon the
+	bonding mode, and the state of the slave).  Regular traffic is
+	generated via ARP probes issued for the addresses specified by
+	the arp_ip_target option.
+
+	This behavior can be modified by the arp_validate option,
+	below.
+
+	If ARP monitoring is used in an etherchannel compatible mode
+	(modes 0 and 2), the switch should be configured in a mode
+	that evenly distributes packets across all links. If the
+	switch is configured to distribute the packets in an XOR
+	fashion, all replies from the ARP targets will be received on
+	the same link which could cause the other team members to
+	fail.  ARP monitoring should not be used in conjunction with
+	miimon.  A value of 0 disables ARP monitoring.  The default
+	value is 0.
+
+arp_ip_target
+
+	Specifies the IP addresses to use as ARP monitoring peers when
+	arp_interval is > 0.  These are the targets of the ARP request
+	sent to determine the health of the link to the targets.
+	Specify these values in ddd.ddd.ddd.ddd format.  Multiple IP
+	addresses must be separated by a comma.  At least one IP
+	address must be given for ARP monitoring to function.  The
+	maximum number of targets that can be specified is 16.  The
+	default value is no IP addresses.
+
+arp_validate
+
+	Specifies whether or not ARP probes and replies should be
+	validated in any mode that supports arp monitoring, or whether
+	non-ARP traffic should be filtered (disregarded) for link
+	monitoring purposes.
+
+	Possible values are:
+
+	none or 0
+
+		No validation or filtering is performed.
+
+	active or 1
+
+		Validation is performed only for the active slave.
+
+	backup or 2
+
+		Validation is performed only for backup slaves.
+
+	all or 3
+
+		Validation is performed for all slaves.
+
+	filter or 4
+
+		Filtering is applied to all slaves. No validation is
+		performed.
+
+	filter_active or 5
+
+		Filtering is applied to all slaves, validation is performed
+		only for the active slave.
+
+	filter_backup or 6
+
+		Filtering is applied to all slaves, validation is performed
+		only for backup slaves.
+
+	Validation:
+
+	Enabling validation causes the ARP monitor to examine the incoming
+	ARP requests and replies, and only consider a slave to be up if it
+	is receiving the appropriate ARP traffic.
+
+	For an active slave, the validation checks ARP replies to confirm
+	that they were generated by an arp_ip_target.  Since backup slaves
+	do not typically receive these replies, the validation performed
+	for backup slaves is on the broadcast ARP request sent out via the
+	active slave.  It is possible that some switch or network
+	configurations may result in situations wherein the backup slaves
+	do not receive the ARP requests; in such a situation, validation
+	of backup slaves must be disabled.
+
+	The validation of ARP requests on backup slaves is mainly helping
+	bonding to decide which slaves are more likely to work in case of
+	the active slave failure, it doesn't really guarantee that the
+	backup slave will work if it's selected as the next active slave.
+
+	Validation is useful in network configurations in which multiple
+	bonding hosts are concurrently issuing ARPs to one or more targets
+	beyond a common switch.  Should the link between the switch and
+	target fail (but not the switch itself), the probe traffic
+	generated by the multiple bonding instances will fool the standard
+	ARP monitor into considering the links as still up.  Use of
+	validation can resolve this, as the ARP monitor will only consider
+	ARP requests and replies associated with its own instance of
+	bonding.
+
+	Filtering:
+
+	Enabling filtering causes the ARP monitor to only use incoming ARP
+	packets for link availability purposes.  Arriving packets that are
+	not ARPs are delivered normally, but do not count when determining
+	if a slave is available.
+
+	Filtering operates by only considering the reception of ARP
+	packets (any ARP packet, regardless of source or destination) when
+	determining if a slave has received traffic for link availability
+	purposes.
+
+	Filtering is useful in network configurations in which significant
+	levels of third party broadcast traffic would fool the standard
+	ARP monitor into considering the links as still up.  Use of
+	filtering can resolve this, as only ARP traffic is considered for
+	link availability purposes.
+
+	This option was added in bonding version 3.1.0.
+
+arp_all_targets
+
+	Specifies the quantity of arp_ip_targets that must be reachable
+	in order for the ARP monitor to consider a slave as being up.
+	This option affects only active-backup mode for slaves with
+	arp_validation enabled.
+
+	Possible values are:
+
+	any or 0
+
+		consider the slave up only when any of the arp_ip_targets
+		is reachable
+
+	all or 1
+
+		consider the slave up only when all of the arp_ip_targets
+		are reachable
+
+downdelay
+
+	Specifies the time, in milliseconds, to wait before disabling
+	a slave after a link failure has been detected.  This option
+	is only valid for the miimon link monitor.  The downdelay
+	value should be a multiple of the miimon value; if not, it
+	will be rounded down to the nearest multiple.  The default
+	value is 0.
+
+fail_over_mac
+
+	Specifies whether active-backup mode should set all slaves to
+	the same MAC address at enslavement (the traditional
+	behavior), or, when enabled, perform special handling of the
+	bond's MAC address in accordance with the selected policy.
+
+	Possible values are:
+
+	none or 0
+
+		This setting disables fail_over_mac, and causes
+		bonding to set all slaves of an active-backup bond to
+		the same MAC address at enslavement time.  This is the
+		default.
+
+	active or 1
+
+		The "active" fail_over_mac policy indicates that the
+		MAC address of the bond should always be the MAC
+		address of the currently active slave.  The MAC
+		address of the slaves is not changed; instead, the MAC
+		address of the bond changes during a failover.
+
+		This policy is useful for devices that cannot ever
+		alter their MAC address, or for devices that refuse
+		incoming broadcasts with their own source MAC (which
+		interferes with the ARP monitor).
+
+		The down side of this policy is that every device on
+		the network must be updated via gratuitous ARP,
+		vs. just updating a switch or set of switches (which
+		often takes place for any traffic, not just ARP
+		traffic, if the switch snoops incoming traffic to
+		update its tables) for the traditional method.  If the
+		gratuitous ARP is lost, communication may be
+		disrupted.
+
+		When this policy is used in conjunction with the mii
+		monitor, devices which assert link up prior to being
+		able to actually transmit and receive are particularly
+		susceptible to loss of the gratuitous ARP, and an
+		appropriate updelay setting may be required.
+
+	follow or 2
+
+		The "follow" fail_over_mac policy causes the MAC
+		address of the bond to be selected normally (normally
+		the MAC address of the first slave added to the bond).
+		However, the second and subsequent slaves are not set
+		to this MAC address while they are in a backup role; a
+		slave is programmed with the bond's MAC address at
+		failover time (and the formerly active slave receives
+		the newly active slave's MAC address).
+
+		This policy is useful for multiport devices that
+		either become confused or incur a performance penalty
+		when multiple ports are programmed with the same MAC
+		address.
+
+
+	The default policy is none, unless the first slave cannot
+	change its MAC address, in which case the active policy is
+	selected by default.
+
+	This option may be modified via sysfs only when no slaves are
+	present in the bond.
+
+	This option was added in bonding version 3.2.0.  The "follow"
+	policy was added in bonding version 3.3.0.
+
+lacp_rate
+
+	Option specifying the rate in which we'll ask our link partner
+	to transmit LACPDU packets in 802.3ad mode.  Possible values
+	are:
+
+	slow or 0
+		Request partner to transmit LACPDUs every 30 seconds
+
+	fast or 1
+		Request partner to transmit LACPDUs every 1 second
+
+	The default is slow.
+
+max_bonds
+
+	Specifies the number of bonding devices to create for this
+	instance of the bonding driver.  E.g., if max_bonds is 3, and
+	the bonding driver is not already loaded, then bond0, bond1
+	and bond2 will be created.  The default value is 1.  Specifying
+	a value of 0 will load bonding, but will not create any devices.
+
+miimon
+
+	Specifies the MII link monitoring frequency in milliseconds.
+	This determines how often the link state of each slave is
+	inspected for link failures.  A value of zero disables MII
+	link monitoring.  A value of 100 is a good starting point.
+	The use_carrier option, below, affects how the link state is
+	determined.  See the High Availability section for additional
+	information.  The default value is 0.
+
+min_links
+
+	Specifies the minimum number of links that must be active before
+	asserting carrier. It is similar to the Cisco EtherChannel min-links
+	feature. This allows setting the minimum number of member ports that
+	must be up (link-up state) before marking the bond device as up
+	(carrier on). This is useful for situations where higher level services
+	such as clustering want to ensure a minimum number of low bandwidth
+	links are active before switchover. This option only affect 802.3ad
+	mode.
+
+	The default value is 0. This will cause carrier to be asserted (for
+	802.3ad mode) whenever there is an active aggregator, regardless of the
+	number of available links in that aggregator. Note that, because an
+	aggregator cannot be active without at least one available link,
+	setting this option to 0 or to 1 has the exact same effect.
+
+mode
+
+	Specifies one of the bonding policies. The default is
+	balance-rr (round robin).  Possible values are:
+
+	balance-rr or 0
+
+		Round-robin policy: Transmit packets in sequential
+		order from the first available slave through the
+		last.  This mode provides load balancing and fault
+		tolerance.
+
+	active-backup or 1
+
+		Active-backup policy: Only one slave in the bond is
+		active.  A different slave becomes active if, and only
+		if, the active slave fails.  The bond's MAC address is
+		externally visible on only one port (network adapter)
+		to avoid confusing the switch.
+
+		In bonding version 2.6.2 or later, when a failover
+		occurs in active-backup mode, bonding will issue one
+		or more gratuitous ARPs on the newly active slave.
+		One gratuitous ARP is issued for the bonding master
+		interface and each VLAN interfaces configured above
+		it, provided that the interface has at least one IP
+		address configured.  Gratuitous ARPs issued for VLAN
+		interfaces are tagged with the appropriate VLAN id.
+
+		This mode provides fault tolerance.  The primary
+		option, documented below, affects the behavior of this
+		mode.
+
+	balance-xor or 2
+
+		XOR policy: Transmit based on the selected transmit
+		hash policy.  The default policy is a simple [(source
+		MAC address XOR'd with destination MAC address XOR
+		packet type ID) modulo slave count].  Alternate transmit
+		policies may be	selected via the xmit_hash_policy option,
+		described below.
+
+		This mode provides load balancing and fault tolerance.
+
+	broadcast or 3
+
+		Broadcast policy: transmits everything on all slave
+		interfaces.  This mode provides fault tolerance.
+
+	802.3ad or 4
+
+		IEEE 802.3ad Dynamic link aggregation.  Creates
+		aggregation groups that share the same speed and
+		duplex settings.  Utilizes all slaves in the active
+		aggregator according to the 802.3ad specification.
+
+		Slave selection for outgoing traffic is done according
+		to the transmit hash policy, which may be changed from
+		the default simple XOR policy via the xmit_hash_policy
+		option, documented below.  Note that not all transmit
+		policies may be 802.3ad compliant, particularly in
+		regards to the packet mis-ordering requirements of
+		section 43.2.4 of the 802.3ad standard.  Differing
+		peer implementations will have varying tolerances for
+		noncompliance.
+
+		Prerequisites:
+
+		1. Ethtool support in the base drivers for retrieving
+		the speed and duplex of each slave.
+
+		2. A switch that supports IEEE 802.3ad Dynamic link
+		aggregation.
+
+		Most switches will require some type of configuration
+		to enable 802.3ad mode.
+
+	balance-tlb or 5
+
+		Adaptive transmit load balancing: channel bonding that
+		does not require any special switch support.
+
+		In tlb_dynamic_lb=1 mode; the outgoing traffic is
+		distributed according to the current load (computed
+		relative to the speed) on each slave.
+
+		In tlb_dynamic_lb=0 mode; the load balancing based on
+		current load is disabled and the load is distributed
+		only using the hash distribution.
+
+		Incoming traffic is received by the current slave.
+		If the receiving slave fails, another slave takes over
+		the MAC address of the failed receiving slave.
+
+		Prerequisite:
+
+		Ethtool support in the base drivers for retrieving the
+		speed of each slave.
+
+	balance-alb or 6
+
+		Adaptive load balancing: includes balance-tlb plus
+		receive load balancing (rlb) for IPV4 traffic, and
+		does not require any special switch support.  The
+		receive load balancing is achieved by ARP negotiation.
+		The bonding driver intercepts the ARP Replies sent by
+		the local system on their way out and overwrites the
+		source hardware address with the unique hardware
+		address of one of the slaves in the bond such that
+		different peers use different hardware addresses for
+		the server.
+
+		Receive traffic from connections created by the server
+		is also balanced.  When the local system sends an ARP
+		Request the bonding driver copies and saves the peer's
+		IP information from the ARP packet.  When the ARP
+		Reply arrives from the peer, its hardware address is
+		retrieved and the bonding driver initiates an ARP
+		reply to this peer assigning it to one of the slaves
+		in the bond.  A problematic outcome of using ARP
+		negotiation for balancing is that each time that an
+		ARP request is broadcast it uses the hardware address
+		of the bond.  Hence, peers learn the hardware address
+		of the bond and the balancing of receive traffic
+		collapses to the current slave.  This is handled by
+		sending updates (ARP Replies) to all the peers with
+		their individually assigned hardware address such that
+		the traffic is redistributed.  Receive traffic is also
+		redistributed when a new slave is added to the bond
+		and when an inactive slave is re-activated.  The
+		receive load is distributed sequentially (round robin)
+		among the group of highest speed slaves in the bond.
+
+		When a link is reconnected or a new slave joins the
+		bond the receive traffic is redistributed among all
+		active slaves in the bond by initiating ARP Replies
+		with the selected MAC address to each of the
+		clients. The updelay parameter (detailed below) must
+		be set to a value equal or greater than the switch's
+		forwarding delay so that the ARP Replies sent to the
+		peers will not be blocked by the switch.
+
+		Prerequisites:
+
+		1. Ethtool support in the base drivers for retrieving
+		the speed of each slave.
+
+		2. Base driver support for setting the hardware
+		address of a device while it is open.  This is
+		required so that there will always be one slave in the
+		team using the bond hardware address (the
+		curr_active_slave) while having a unique hardware
+		address for each slave in the bond.  If the
+		curr_active_slave fails its hardware address is
+		swapped with the new curr_active_slave that was
+		chosen.
+
+num_grat_arp,
+num_unsol_na
+
+	Specify the number of peer notifications (gratuitous ARPs and
+	unsolicited IPv6 Neighbor Advertisements) to be issued after a
+	failover event.  As soon as the link is up on the new slave
+	(possibly immediately) a peer notification is sent on the
+	bonding device and each VLAN sub-device. This is repeated at
+	the rate specified by peer_notif_delay if the number is
+	greater than 1.
+
+	The valid range is 0 - 255; the default value is 1.  These options
+	affect only the active-backup mode.  These options were added for
+	bonding versions 3.3.0 and 3.4.0 respectively.
+
+	From Linux 3.0 and bonding version 3.7.1, these notifications
+	are generated by the ipv4 and ipv6 code and the numbers of
+	repetitions cannot be set independently.
+
+packets_per_slave
+
+	Specify the number of packets to transmit through a slave before
+	moving to the next one. When set to 0 then a slave is chosen at
+	random.
+
+	The valid range is 0 - 65535; the default value is 1. This option
+	has effect only in balance-rr mode.
+
+peer_notif_delay
+
+	Specify the delay, in milliseconds, between each peer
+	notification (gratuitous ARP and unsolicited IPv6 Neighbor
+	Advertisement) when they are issued after a failover event.
+	This delay should be a multiple of the link monitor interval
+	(arp_interval or miimon, whichever is active). The default
+	value is 0 which means to match the value of the link monitor
+	interval.
+
+primary
+
+	A string (eth0, eth2, etc) specifying which slave is the
+	primary device.  The specified device will always be the
+	active slave while it is available.  Only when the primary is
+	off-line will alternate devices be used.  This is useful when
+	one slave is preferred over another, e.g., when one slave has
+	higher throughput than another.
+
+	The primary option is only valid for active-backup(1),
+	balance-tlb (5) and balance-alb (6) mode.
+
+primary_reselect
+
+	Specifies the reselection policy for the primary slave.  This
+	affects how the primary slave is chosen to become the active slave
+	when failure of the active slave or recovery of the primary slave
+	occurs.  This option is designed to prevent flip-flopping between
+	the primary slave and other slaves.  Possible values are:
+
+	always or 0 (default)
+
+		The primary slave becomes the active slave whenever it
+		comes back up.
+
+	better or 1
+
+		The primary slave becomes the active slave when it comes
+		back up, if the speed and duplex of the primary slave is
+		better than the speed and duplex of the current active
+		slave.
+
+	failure or 2
+
+		The primary slave becomes the active slave only if the
+		current active slave fails and the primary slave is up.
+
+	The primary_reselect setting is ignored in two cases:
+
+		If no slaves are active, the first slave to recover is
+		made the active slave.
+
+		When initially enslaved, the primary slave is always made
+		the active slave.
+
+	Changing the primary_reselect policy via sysfs will cause an
+	immediate selection of the best active slave according to the new
+	policy.  This may or may not result in a change of the active
+	slave, depending upon the circumstances.
+
+	This option was added for bonding version 3.6.0.
+
+tlb_dynamic_lb
+
+	Specifies if dynamic shuffling of flows is enabled in tlb
+	mode. The value has no effect on any other modes.
+
+	The default behavior of tlb mode is to shuffle active flows across
+	slaves based on the load in that interval. This gives nice lb
+	characteristics but can cause packet reordering. If re-ordering is
+	a concern use this variable to disable flow shuffling and rely on
+	load balancing provided solely by the hash distribution.
+	xmit-hash-policy can be used to select the appropriate hashing for
+	the setup.
+
+	The sysfs entry can be used to change the setting per bond device
+	and the initial value is derived from the module parameter. The
+	sysfs entry is allowed to be changed only if the bond device is
+	down.
+
+	The default value is "1" that enables flow shuffling while value "0"
+	disables it. This option was added in bonding driver 3.7.1
+
+
+updelay
+
+	Specifies the time, in milliseconds, to wait before enabling a
+	slave after a link recovery has been detected.  This option is
+	only valid for the miimon link monitor.  The updelay value
+	should be a multiple of the miimon value; if not, it will be
+	rounded down to the nearest multiple.  The default value is 0.
+
+use_carrier
+
+	Specifies whether or not miimon should use MII or ETHTOOL
+	ioctls vs. netif_carrier_ok() to determine the link
+	status. The MII or ETHTOOL ioctls are less efficient and
+	utilize a deprecated calling sequence within the kernel.  The
+	netif_carrier_ok() relies on the device driver to maintain its
+	state with netif_carrier_on/off; at this writing, most, but
+	not all, device drivers support this facility.
+
+	If bonding insists that the link is up when it should not be,
+	it may be that your network device driver does not support
+	netif_carrier_on/off.  The default state for netif_carrier is
+	"carrier on," so if a driver does not support netif_carrier,
+	it will appear as if the link is always up.  In this case,
+	setting use_carrier to 0 will cause bonding to revert to the
+	MII / ETHTOOL ioctl method to determine the link state.
+
+	A value of 1 enables the use of netif_carrier_ok(), a value of
+	0 will use the deprecated MII / ETHTOOL ioctls.  The default
+	value is 1.
+
+xmit_hash_policy
+
+	Selects the transmit hash policy to use for slave selection in
+	balance-xor, 802.3ad, and tlb modes.  Possible values are:
+
+	layer2
+
+		Uses XOR of hardware MAC addresses and packet type ID
+		field to generate the hash. The formula is
+
+		hash = source MAC XOR destination MAC XOR packet type ID
+		slave number = hash modulo slave count
+
+		This algorithm will place all traffic to a particular
+		network peer on the same slave.
+
+		This algorithm is 802.3ad compliant.
+
+	layer2+3
+
+		This policy uses a combination of layer2 and layer3
+		protocol information to generate the hash.
+
+		Uses XOR of hardware MAC addresses and IP addresses to
+		generate the hash.  The formula is
+
+		hash = source MAC XOR destination MAC XOR packet type ID
+		hash = hash XOR source IP XOR destination IP
+		hash = hash XOR (hash RSHIFT 16)
+		hash = hash XOR (hash RSHIFT 8)
+		And then hash is reduced modulo slave count.
+
+		If the protocol is IPv6 then the source and destination
+		addresses are first hashed using ipv6_addr_hash.
+
+		This algorithm will place all traffic to a particular
+		network peer on the same slave.  For non-IP traffic,
+		the formula is the same as for the layer2 transmit
+		hash policy.
+
+		This policy is intended to provide a more balanced
+		distribution of traffic than layer2 alone, especially
+		in environments where a layer3 gateway device is
+		required to reach most destinations.
+
+		This algorithm is 802.3ad compliant.
+
+	layer3+4
+
+		This policy uses upper layer protocol information,
+		when available, to generate the hash.  This allows for
+		traffic to a particular network peer to span multiple
+		slaves, although a single connection will not span
+		multiple slaves.
+
+		The formula for unfragmented TCP and UDP packets is
+
+		hash = source port, destination port (as in the header)
+		hash = hash XOR source IP XOR destination IP
+		hash = hash XOR (hash RSHIFT 16)
+		hash = hash XOR (hash RSHIFT 8)
+		And then hash is reduced modulo slave count.
+
+		If the protocol is IPv6 then the source and destination
+		addresses are first hashed using ipv6_addr_hash.
+
+		For fragmented TCP or UDP packets and all other IPv4 and
+		IPv6 protocol traffic, the source and destination port
+		information is omitted.  For non-IP traffic, the
+		formula is the same as for the layer2 transmit hash
+		policy.
+
+		This algorithm is not fully 802.3ad compliant.  A
+		single TCP or UDP conversation containing both
+		fragmented and unfragmented packets will see packets
+		striped across two interfaces.  This may result in out
+		of order delivery.  Most traffic types will not meet
+		this criteria, as TCP rarely fragments traffic, and
+		most UDP traffic is not involved in extended
+		conversations.  Other implementations of 802.3ad may
+		or may not tolerate this noncompliance.
+
+	encap2+3
+
+		This policy uses the same formula as layer2+3 but it
+		relies on skb_flow_dissect to obtain the header fields
+		which might result in the use of inner headers if an
+		encapsulation protocol is used. For example this will
+		improve the performance for tunnel users because the
+		packets will be distributed according to the encapsulated
+		flows.
+
+	encap3+4
+
+		This policy uses the same formula as layer3+4 but it
+		relies on skb_flow_dissect to obtain the header fields
+		which might result in the use of inner headers if an
+		encapsulation protocol is used. For example this will
+		improve the performance for tunnel users because the
+		packets will be distributed according to the encapsulated
+		flows.
+
+	The default value is layer2.  This option was added in bonding
+	version 2.6.3.  In earlier versions of bonding, this parameter
+	does not exist, and the layer2 policy is the only policy.  The
+	layer2+3 value was added for bonding version 3.2.2.
+
+resend_igmp
+
+	Specifies the number of IGMP membership reports to be issued after
+	a failover event. One membership report is issued immediately after
+	the failover, subsequent packets are sent in each 200ms interval.
+
+	The valid range is 0 - 255; the default value is 1. A value of 0
+	prevents the IGMP membership report from being issued in response
+	to the failover event.
+
+	This option is useful for bonding modes balance-rr (0), active-backup
+	(1), balance-tlb (5) and balance-alb (6), in which a failover can
+	switch the IGMP traffic from one slave to another.  Therefore a fresh
+	IGMP report must be issued to cause the switch to forward the incoming
+	IGMP traffic over the newly selected slave.
+
+	This option was added for bonding version 3.7.0.
+
+lp_interval
+
+	Specifies the number of seconds between instances where the bonding
+	driver sends learning packets to each slaves peer switch.
+
+	The valid range is 1 - 0x7fffffff; the default value is 1. This Option
+	has effect only in balance-tlb and balance-alb modes.
+
+3. Configuring Bonding Devices
+==============================
+
+You can configure bonding using either your distro's network
+initialization scripts, or manually using either iproute2 or the
+sysfs interface.  Distros generally use one of three packages for the
+network initialization scripts: initscripts, sysconfig or interfaces.
+Recent versions of these packages have support for bonding, while older
+versions do not.
+
+We will first describe the options for configuring bonding for
+distros using versions of initscripts, sysconfig and interfaces with full
+or partial support for bonding, then provide information on enabling
+bonding without support from the network initialization scripts (i.e.,
+older versions of initscripts or sysconfig).
+
+If you're unsure whether your distro uses sysconfig,
+initscripts or interfaces, or don't know if it's new enough, have no fear.
+Determining this is fairly straightforward.
+
+First, look for a file called interfaces in /etc/network directory.
+If this file is present in your system, then your system use interfaces. See
+Configuration with Interfaces Support.
+
+Else, issue the command::
+
+	$ rpm -qf /sbin/ifup
+
+It will respond with a line of text starting with either
+"initscripts" or "sysconfig," followed by some numbers.  This is the
+package that provides your network initialization scripts.
+
+Next, to determine if your installation supports bonding,
+issue the command::
+
+    $ grep ifenslave /sbin/ifup
+
+If this returns any matches, then your initscripts or
+sysconfig has support for bonding.
+
+3.1 Configuration with Sysconfig Support
+----------------------------------------
+
+This section applies to distros using a version of sysconfig
+with bonding support, for example, SuSE Linux Enterprise Server 9.
+
+SuSE SLES 9's networking configuration system does support
+bonding, however, at this writing, the YaST system configuration
+front end does not provide any means to work with bonding devices.
+Bonding devices can be managed by hand, however, as follows.
+
+First, if they have not already been configured, configure the
+slave devices.  On SLES 9, this is most easily done by running the
+yast2 sysconfig configuration utility.  The goal is for to create an
+ifcfg-id file for each slave device.  The simplest way to accomplish
+this is to configure the devices for DHCP (this is only to get the
+file ifcfg-id file created; see below for some issues with DHCP).  The
+name of the configuration file for each device will be of the form::
+
+    ifcfg-id-xx:xx:xx:xx:xx:xx
+
+Where the "xx" portion will be replaced with the digits from
+the device's permanent MAC address.
+
+Once the set of ifcfg-id-xx:xx:xx:xx:xx:xx files has been
+created, it is necessary to edit the configuration files for the slave
+devices (the MAC addresses correspond to those of the slave devices).
+Before editing, the file will contain multiple lines, and will look
+something like this::
+
+	BOOTPROTO='dhcp'
+	STARTMODE='on'
+	USERCTL='no'
+	UNIQUE='XNzu.WeZGOGF+4wE'
+	_nm_name='bus-pci-0001:61:01.0'
+
+Change the BOOTPROTO and STARTMODE lines to the following::
+
+	BOOTPROTO='none'
+	STARTMODE='off'
+
+Do not alter the UNIQUE or _nm_name lines.  Remove any other
+lines (USERCTL, etc).
+
+Once the ifcfg-id-xx:xx:xx:xx:xx:xx files have been modified,
+it's time to create the configuration file for the bonding device
+itself.  This file is named ifcfg-bondX, where X is the number of the
+bonding device to create, starting at 0.  The first such file is
+ifcfg-bond0, the second is ifcfg-bond1, and so on.  The sysconfig
+network configuration system will correctly start multiple instances
+of bonding.
+
+The contents of the ifcfg-bondX file is as follows::
+
+	BOOTPROTO="static"
+	BROADCAST="10.0.2.255"
+	IPADDR="10.0.2.10"
+	NETMASK="255.255.0.0"
+	NETWORK="10.0.2.0"
+	REMOTE_IPADDR=""
+	STARTMODE="onboot"
+	BONDING_MASTER="yes"
+	BONDING_MODULE_OPTS="mode=active-backup miimon=100"
+	BONDING_SLAVE0="eth0"
+	BONDING_SLAVE1="bus-pci-0000:06:08.1"
+
+Replace the sample BROADCAST, IPADDR, NETMASK and NETWORK
+values with the appropriate values for your network.
+
+The STARTMODE specifies when the device is brought online.
+The possible values are:
+
+	======== ======================================================
+	onboot	 The device is started at boot time.  If you're not
+		 sure, this is probably what you want.
+
+	manual	 The device is started only when ifup is called
+		 manually.  Bonding devices may be configured this
+		 way if you do not wish them to start automatically
+		 at boot for some reason.
+
+	hotplug  The device is started by a hotplug event.  This is not
+		 a valid choice for a bonding device.
+
+	off or   The device configuration is ignored.
+	ignore
+	======== ======================================================
+
+The line BONDING_MASTER='yes' indicates that the device is a
+bonding master device.  The only useful value is "yes."
+
+The contents of BONDING_MODULE_OPTS are supplied to the
+instance of the bonding module for this device.  Specify the options
+for the bonding mode, link monitoring, and so on here.  Do not include
+the max_bonds bonding parameter; this will confuse the configuration
+system if you have multiple bonding devices.
+
+Finally, supply one BONDING_SLAVEn="slave device" for each
+slave.  where "n" is an increasing value, one for each slave.  The
+"slave device" is either an interface name, e.g., "eth0", or a device
+specifier for the network device.  The interface name is easier to
+find, but the ethN names are subject to change at boot time if, e.g.,
+a device early in the sequence has failed.  The device specifiers
+(bus-pci-0000:06:08.1 in the example above) specify the physical
+network device, and will not change unless the device's bus location
+changes (for example, it is moved from one PCI slot to another).  The
+example above uses one of each type for demonstration purposes; most
+configurations will choose one or the other for all slave devices.
+
+When all configuration files have been modified or created,
+networking must be restarted for the configuration changes to take
+effect.  This can be accomplished via the following::
+
+	# /etc/init.d/network restart
+
+Note that the network control script (/sbin/ifdown) will
+remove the bonding module as part of the network shutdown processing,
+so it is not necessary to remove the module by hand if, e.g., the
+module parameters have changed.
+
+Also, at this writing, YaST/YaST2 will not manage bonding
+devices (they do not show bonding interfaces on its list of network
+devices).  It is necessary to edit the configuration file by hand to
+change the bonding configuration.
+
+Additional general options and details of the ifcfg file
+format can be found in an example ifcfg template file::
+
+	/etc/sysconfig/network/ifcfg.template
+
+Note that the template does not document the various ``BONDING_*``
+settings described above, but does describe many of the other options.
+
+3.1.1 Using DHCP with Sysconfig
+-------------------------------
+
+Under sysconfig, configuring a device with BOOTPROTO='dhcp'
+will cause it to query DHCP for its IP address information.  At this
+writing, this does not function for bonding devices; the scripts
+attempt to obtain the device address from DHCP prior to adding any of
+the slave devices.  Without active slaves, the DHCP requests are not
+sent to the network.
+
+3.1.2 Configuring Multiple Bonds with Sysconfig
+-----------------------------------------------
+
+The sysconfig network initialization system is capable of
+handling multiple bonding devices.  All that is necessary is for each
+bonding instance to have an appropriately configured ifcfg-bondX file
+(as described above).  Do not specify the "max_bonds" parameter to any
+instance of bonding, as this will confuse sysconfig.  If you require
+multiple bonding devices with identical parameters, create multiple
+ifcfg-bondX files.
+
+Because the sysconfig scripts supply the bonding module
+options in the ifcfg-bondX file, it is not necessary to add them to
+the system ``/etc/modules.d/*.conf`` configuration files.
+
+3.2 Configuration with Initscripts Support
+------------------------------------------
+
+This section applies to distros using a recent version of
+initscripts with bonding support, for example, Red Hat Enterprise Linux
+version 3 or later, Fedora, etc.  On these systems, the network
+initialization scripts have knowledge of bonding, and can be configured to
+control bonding devices.  Note that older versions of the initscripts
+package have lower levels of support for bonding; this will be noted where
+applicable.
+
+These distros will not automatically load the network adapter
+driver unless the ethX device is configured with an IP address.
+Because of this constraint, users must manually configure a
+network-script file for all physical adapters that will be members of
+a bondX link.  Network script files are located in the directory:
+
+/etc/sysconfig/network-scripts
+
+The file name must be prefixed with "ifcfg-eth" and suffixed
+with the adapter's physical adapter number.  For example, the script
+for eth0 would be named /etc/sysconfig/network-scripts/ifcfg-eth0.
+Place the following text in the file::
+
+	DEVICE=eth0
+	USERCTL=no
+	ONBOOT=yes
+	MASTER=bond0
+	SLAVE=yes
+	BOOTPROTO=none
+
+The DEVICE= line will be different for every ethX device and
+must correspond with the name of the file, i.e., ifcfg-eth1 must have
+a device line of DEVICE=eth1.  The setting of the MASTER= line will
+also depend on the final bonding interface name chosen for your bond.
+As with other network devices, these typically start at 0, and go up
+one for each device, i.e., the first bonding instance is bond0, the
+second is bond1, and so on.
+
+Next, create a bond network script.  The file name for this
+script will be /etc/sysconfig/network-scripts/ifcfg-bondX where X is
+the number of the bond.  For bond0 the file is named "ifcfg-bond0",
+for bond1 it is named "ifcfg-bond1", and so on.  Within that file,
+place the following text::
+
+	DEVICE=bond0
+	IPADDR=192.168.1.1
+	NETMASK=255.255.255.0
+	NETWORK=192.168.1.0
+	BROADCAST=192.168.1.255
+	ONBOOT=yes
+	BOOTPROTO=none
+	USERCTL=no
+
+Be sure to change the networking specific lines (IPADDR,
+NETMASK, NETWORK and BROADCAST) to match your network configuration.
+
+For later versions of initscripts, such as that found with Fedora
+7 (or later) and Red Hat Enterprise Linux version 5 (or later), it is possible,
+and, indeed, preferable, to specify the bonding options in the ifcfg-bond0
+file, e.g. a line of the format::
+
+  BONDING_OPTS="mode=active-backup arp_interval=60 arp_ip_target=192.168.1.254"
+
+will configure the bond with the specified options.  The options
+specified in BONDING_OPTS are identical to the bonding module parameters
+except for the arp_ip_target field when using versions of initscripts older
+than and 8.57 (Fedora 8) and 8.45.19 (Red Hat Enterprise Linux 5.2).  When
+using older versions each target should be included as a separate option and
+should be preceded by a '+' to indicate it should be added to the list of
+queried targets, e.g.,::
+
+    arp_ip_target=+192.168.1.1 arp_ip_target=+192.168.1.2
+
+is the proper syntax to specify multiple targets.  When specifying
+options via BONDING_OPTS, it is not necessary to edit
+``/etc/modprobe.d/*.conf``.
+
+For even older versions of initscripts that do not support
+BONDING_OPTS, it is necessary to edit /etc/modprobe.d/*.conf, depending upon
+your distro) to load the bonding module with your desired options when the
+bond0 interface is brought up.  The following lines in /etc/modprobe.d/*.conf
+will load the bonding module, and select its options:
+
+	alias bond0 bonding
+	options bond0 mode=balance-alb miimon=100
+
+Replace the sample parameters with the appropriate set of
+options for your configuration.
+
+Finally run "/etc/rc.d/init.d/network restart" as root.  This
+will restart the networking subsystem and your bond link should be now
+up and running.
+
+3.2.1 Using DHCP with Initscripts
+---------------------------------
+
+Recent versions of initscripts (the versions supplied with Fedora
+Core 3 and Red Hat Enterprise Linux 4, or later versions, are reported to
+work) have support for assigning IP information to bonding devices via
+DHCP.
+
+To configure bonding for DHCP, configure it as described
+above, except replace the line "BOOTPROTO=none" with "BOOTPROTO=dhcp"
+and add a line consisting of "TYPE=Bonding".  Note that the TYPE value
+is case sensitive.
+
+3.2.2 Configuring Multiple Bonds with Initscripts
+-------------------------------------------------
+
+Initscripts packages that are included with Fedora 7 and Red Hat
+Enterprise Linux 5 support multiple bonding interfaces by simply
+specifying the appropriate BONDING_OPTS= in ifcfg-bondX where X is the
+number of the bond.  This support requires sysfs support in the kernel,
+and a bonding driver of version 3.0.0 or later.  Other configurations may
+not support this method for specifying multiple bonding interfaces; for
+those instances, see the "Configuring Multiple Bonds Manually" section,
+below.
+
+3.3 Configuring Bonding Manually with iproute2
+-----------------------------------------------
+
+This section applies to distros whose network initialization
+scripts (the sysconfig or initscripts package) do not have specific
+knowledge of bonding.  One such distro is SuSE Linux Enterprise Server
+version 8.
+
+The general method for these systems is to place the bonding
+module parameters into a config file in /etc/modprobe.d/ (as
+appropriate for the installed distro), then add modprobe and/or
+`ip link` commands to the system's global init script.  The name of
+the global init script differs; for sysconfig, it is
+/etc/init.d/boot.local and for initscripts it is /etc/rc.d/rc.local.
+
+For example, if you wanted to make a simple bond of two e100
+devices (presumed to be eth0 and eth1), and have it persist across
+reboots, edit the appropriate file (/etc/init.d/boot.local or
+/etc/rc.d/rc.local), and add the following::
+
+	modprobe bonding mode=balance-alb miimon=100
+	modprobe e100
+	ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up
+	ip link set eth0 master bond0
+	ip link set eth1 master bond0
+
+Replace the example bonding module parameters and bond0
+network configuration (IP address, netmask, etc) with the appropriate
+values for your configuration.
+
+Unfortunately, this method will not provide support for the
+ifup and ifdown scripts on the bond devices.  To reload the bonding
+configuration, it is necessary to run the initialization script, e.g.,::
+
+	# /etc/init.d/boot.local
+
+or::
+
+	# /etc/rc.d/rc.local
+
+It may be desirable in such a case to create a separate script
+which only initializes the bonding configuration, then call that
+separate script from within boot.local.  This allows for bonding to be
+enabled without re-running the entire global init script.
+
+To shut down the bonding devices, it is necessary to first
+mark the bonding device itself as being down, then remove the
+appropriate device driver modules.  For our example above, you can do
+the following::
+
+	# ifconfig bond0 down
+	# rmmod bonding
+	# rmmod e100
+
+Again, for convenience, it may be desirable to create a script
+with these commands.
+
+
+3.3.1 Configuring Multiple Bonds Manually
+-----------------------------------------
+
+This section contains information on configuring multiple
+bonding devices with differing options for those systems whose network
+initialization scripts lack support for configuring multiple bonds.
+
+If you require multiple bonding devices, but all with the same
+options, you may wish to use the "max_bonds" module parameter,
+documented above.
+
+To create multiple bonding devices with differing options, it is
+preferable to use bonding parameters exported by sysfs, documented in the
+section below.
+
+For versions of bonding without sysfs support, the only means to
+provide multiple instances of bonding with differing options is to load
+the bonding driver multiple times.  Note that current versions of the
+sysconfig network initialization scripts handle this automatically; if
+your distro uses these scripts, no special action is needed.  See the
+section Configuring Bonding Devices, above, if you're not sure about your
+network initialization scripts.
+
+To load multiple instances of the module, it is necessary to
+specify a different name for each instance (the module loading system
+requires that every loaded module, even multiple instances of the same
+module, have a unique name).  This is accomplished by supplying multiple
+sets of bonding options in ``/etc/modprobe.d/*.conf``, for example::
+
+	alias bond0 bonding
+	options bond0 -o bond0 mode=balance-rr miimon=100
+
+	alias bond1 bonding
+	options bond1 -o bond1 mode=balance-alb miimon=50
+
+will load the bonding module two times.  The first instance is
+named "bond0" and creates the bond0 device in balance-rr mode with an
+miimon of 100.  The second instance is named "bond1" and creates the
+bond1 device in balance-alb mode with an miimon of 50.
+
+In some circumstances (typically with older distributions),
+the above does not work, and the second bonding instance never sees
+its options.  In that case, the second options line can be substituted
+as follows::
+
+	install bond1 /sbin/modprobe --ignore-install bonding -o bond1 \
+				     mode=balance-alb miimon=50
+
+This may be repeated any number of times, specifying a new and
+unique name in place of bond1 for each subsequent instance.
+
+It has been observed that some Red Hat supplied kernels are unable
+to rename modules at load time (the "-o bond1" part).  Attempts to pass
+that option to modprobe will produce an "Operation not permitted" error.
+This has been reported on some Fedora Core kernels, and has been seen on
+RHEL 4 as well.  On kernels exhibiting this problem, it will be impossible
+to configure multiple bonds with differing parameters (as they are older
+kernels, and also lack sysfs support).
+
+3.4 Configuring Bonding Manually via Sysfs
+------------------------------------------
+
+Starting with version 3.0.0, Channel Bonding may be configured
+via the sysfs interface.  This interface allows dynamic configuration
+of all bonds in the system without unloading the module.  It also
+allows for adding and removing bonds at runtime.  Ifenslave is no
+longer required, though it is still supported.
+
+Use of the sysfs interface allows you to use multiple bonds
+with different configurations without having to reload the module.
+It also allows you to use multiple, differently configured bonds when
+bonding is compiled into the kernel.
+
+You must have the sysfs filesystem mounted to configure
+bonding this way.  The examples in this document assume that you
+are using the standard mount point for sysfs, e.g. /sys.  If your
+sysfs filesystem is mounted elsewhere, you will need to adjust the
+example paths accordingly.
+
+Creating and Destroying Bonds
+-----------------------------
+To add a new bond foo::
+
+	# echo +foo > /sys/class/net/bonding_masters
+
+To remove an existing bond bar::
+
+	# echo -bar > /sys/class/net/bonding_masters
+
+To show all existing bonds::
+
+	# cat /sys/class/net/bonding_masters
+
+.. note::
+
+   due to 4K size limitation of sysfs files, this list may be
+   truncated if you have more than a few hundred bonds.  This is unlikely
+   to occur under normal operating conditions.
+
+Adding and Removing Slaves
+--------------------------
+Interfaces may be enslaved to a bond using the file
+/sys/class/net/<bond>/bonding/slaves.  The semantics for this file
+are the same as for the bonding_masters file.
+
+To enslave interface eth0 to bond bond0::
+
+	# ifconfig bond0 up
+	# echo +eth0 > /sys/class/net/bond0/bonding/slaves
+
+To free slave eth0 from bond bond0::
+
+	# echo -eth0 > /sys/class/net/bond0/bonding/slaves
+
+When an interface is enslaved to a bond, symlinks between the
+two are created in the sysfs filesystem.  In this case, you would get
+/sys/class/net/bond0/slave_eth0 pointing to /sys/class/net/eth0, and
+/sys/class/net/eth0/master pointing to /sys/class/net/bond0.
+
+This means that you can tell quickly whether or not an
+interface is enslaved by looking for the master symlink.  Thus:
+# echo -eth0 > /sys/class/net/eth0/master/bonding/slaves
+will free eth0 from whatever bond it is enslaved to, regardless of
+the name of the bond interface.
+
+Changing a Bond's Configuration
+-------------------------------
+Each bond may be configured individually by manipulating the
+files located in /sys/class/net/<bond name>/bonding
+
+The names of these files correspond directly with the command-
+line parameters described elsewhere in this file, and, with the
+exception of arp_ip_target, they accept the same values.  To see the
+current setting, simply cat the appropriate file.
+
+A few examples will be given here; for specific usage
+guidelines for each parameter, see the appropriate section in this
+document.
+
+To configure bond0 for balance-alb mode::
+
+	# ifconfig bond0 down
+	# echo 6 > /sys/class/net/bond0/bonding/mode
+	- or -
+	# echo balance-alb > /sys/class/net/bond0/bonding/mode
+
+.. note::
+
+   The bond interface must be down before the mode can be changed.
+
+To enable MII monitoring on bond0 with a 1 second interval::
+
+	# echo 1000 > /sys/class/net/bond0/bonding/miimon
+
+.. note::
+
+   If ARP monitoring is enabled, it will disabled when MII
+   monitoring is enabled, and vice-versa.
+
+To add ARP targets::
+
+	# echo +192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target
+	# echo +192.168.0.101 > /sys/class/net/bond0/bonding/arp_ip_target
+
+.. note::
+
+   up to 16 target addresses may be specified.
+
+To remove an ARP target::
+
+	# echo -192.168.0.100 > /sys/class/net/bond0/bonding/arp_ip_target
+
+To configure the interval between learning packet transmits::
+
+	# echo 12 > /sys/class/net/bond0/bonding/lp_interval
+
+.. note::
+
+   the lp_interval is the number of seconds between instances where
+   the bonding driver sends learning packets to each slaves peer switch.  The
+   default interval is 1 second.
+
+Example Configuration
+---------------------
+We begin with the same example that is shown in section 3.3,
+executed with sysfs, and without using ifenslave.
+
+To make a simple bond of two e100 devices (presumed to be eth0
+and eth1), and have it persist across reboots, edit the appropriate
+file (/etc/init.d/boot.local or /etc/rc.d/rc.local), and add the
+following::
+
+	modprobe bonding
+	modprobe e100
+	echo balance-alb > /sys/class/net/bond0/bonding/mode
+	ifconfig bond0 192.168.1.1 netmask 255.255.255.0 up
+	echo 100 > /sys/class/net/bond0/bonding/miimon
+	echo +eth0 > /sys/class/net/bond0/bonding/slaves
+	echo +eth1 > /sys/class/net/bond0/bonding/slaves
+
+To add a second bond, with two e1000 interfaces in
+active-backup mode, using ARP monitoring, add the following lines to
+your init script::
+
+	modprobe e1000
+	echo +bond1 > /sys/class/net/bonding_masters
+	echo active-backup > /sys/class/net/bond1/bonding/mode
+	ifconfig bond1 192.168.2.1 netmask 255.255.255.0 up
+	echo +192.168.2.100 /sys/class/net/bond1/bonding/arp_ip_target
+	echo 2000 > /sys/class/net/bond1/bonding/arp_interval
+	echo +eth2 > /sys/class/net/bond1/bonding/slaves
+	echo +eth3 > /sys/class/net/bond1/bonding/slaves
+
+3.5 Configuration with Interfaces Support
+-----------------------------------------
+
+This section applies to distros which use /etc/network/interfaces file
+to describe network interface configuration, most notably Debian and it's
+derivatives.
+
+The ifup and ifdown commands on Debian don't support bonding out of
+the box. The ifenslave-2.6 package should be installed to provide bonding
+support.  Once installed, this package will provide ``bond-*`` options
+to be used into /etc/network/interfaces.
+
+Note that ifenslave-2.6 package will load the bonding module and use
+the ifenslave command when appropriate.
+
+Example Configurations
+----------------------
+
+In /etc/network/interfaces, the following stanza will configure bond0, in
+active-backup mode, with eth0 and eth1 as slaves::
+
+	auto bond0
+	iface bond0 inet dhcp
+		bond-slaves eth0 eth1
+		bond-mode active-backup
+		bond-miimon 100
+		bond-primary eth0 eth1
+
+If the above configuration doesn't work, you might have a system using
+upstart for system startup. This is most notably true for recent
+Ubuntu versions. The following stanza in /etc/network/interfaces will
+produce the same result on those systems::
+
+	auto bond0
+	iface bond0 inet dhcp
+		bond-slaves none
+		bond-mode active-backup
+		bond-miimon 100
+
+	auto eth0
+	iface eth0 inet manual
+		bond-master bond0
+		bond-primary eth0 eth1
+
+	auto eth1
+	iface eth1 inet manual
+		bond-master bond0
+		bond-primary eth0 eth1
+
+For a full list of ``bond-*`` supported options in /etc/network/interfaces and
+some more advanced examples tailored to you particular distros, see the files in
+/usr/share/doc/ifenslave-2.6.
+
+3.6 Overriding Configuration for Special Cases
+----------------------------------------------
+
+When using the bonding driver, the physical port which transmits a frame is
+typically selected by the bonding driver, and is not relevant to the user or
+system administrator.  The output port is simply selected using the policies of
+the selected bonding mode.  On occasion however, it is helpful to direct certain
+classes of traffic to certain physical interfaces on output to implement
+slightly more complex policies.  For example, to reach a web server over a
+bonded interface in which eth0 connects to a private network, while eth1
+connects via a public network, it may be desirous to bias the bond to send said
+traffic over eth0 first, using eth1 only as a fall back, while all other traffic
+can safely be sent over either interface.  Such configurations may be achieved
+using the traffic control utilities inherent in linux.
+
+By default the bonding driver is multiqueue aware and 16 queues are created
+when the driver initializes (see Documentation/networking/multiqueue.rst
+for details).  If more or less queues are desired the module parameter
+tx_queues can be used to change this value.  There is no sysfs parameter
+available as the allocation is done at module init time.
+
+The output of the file /proc/net/bonding/bondX has changed so the output Queue
+ID is now printed for each slave::
+
+	Bonding Mode: fault-tolerance (active-backup)
+	Primary Slave: None
+	Currently Active Slave: eth0
+	MII Status: up
+	MII Polling Interval (ms): 0
+	Up Delay (ms): 0
+	Down Delay (ms): 0
+
+	Slave Interface: eth0
+	MII Status: up
+	Link Failure Count: 0
+	Permanent HW addr: 00:1a:a0:12:8f:cb
+	Slave queue ID: 0
+
+	Slave Interface: eth1
+	MII Status: up
+	Link Failure Count: 0
+	Permanent HW addr: 00:1a:a0:12:8f:cc
+	Slave queue ID: 2
+
+The queue_id for a slave can be set using the command::
+
+	# echo "eth1:2" > /sys/class/net/bond0/bonding/queue_id
+
+Any interface that needs a queue_id set should set it with multiple calls
+like the one above until proper priorities are set for all interfaces.  On
+distributions that allow configuration via initscripts, multiple 'queue_id'
+arguments can be added to BONDING_OPTS to set all needed slave queues.
+
+These queue id's can be used in conjunction with the tc utility to configure
+a multiqueue qdisc and filters to bias certain traffic to transmit on certain
+slave devices.  For instance, say we wanted, in the above configuration to
+force all traffic bound to 192.168.1.100 to use eth1 in the bond as its output
+device. The following commands would accomplish this::
+
+	# tc qdisc add dev bond0 handle 1 root multiq
+
+	# tc filter add dev bond0 protocol ip parent 1: prio 1 u32 match ip \
+		dst 192.168.1.100 action skbedit queue_mapping 2
+
+These commands tell the kernel to attach a multiqueue queue discipline to the
+bond0 interface and filter traffic enqueued to it, such that packets with a dst
+ip of 192.168.1.100 have their output queue mapping value overwritten to 2.
+This value is then passed into the driver, causing the normal output path
+selection policy to be overridden, selecting instead qid 2, which maps to eth1.
+
+Note that qid values begin at 1.  Qid 0 is reserved to initiate to the driver
+that normal output policy selection should take place.  One benefit to simply
+leaving the qid for a slave to 0 is the multiqueue awareness in the bonding
+driver that is now present.  This awareness allows tc filters to be placed on
+slave devices as well as bond devices and the bonding driver will simply act as
+a pass-through for selecting output queues on the slave device rather than
+output port selection.
+
+This feature first appeared in bonding driver version 3.7.0 and support for
+output slave selection was limited to round-robin and active-backup modes.
+
+3.7 Configuring LACP for 802.3ad mode in a more secure way
+----------------------------------------------------------
+
+When using 802.3ad bonding mode, the Actor (host) and Partner (switch)
+exchange LACPDUs.  These LACPDUs cannot be sniffed, because they are
+destined to link local mac addresses (which switches/bridges are not
+supposed to forward).  However, most of the values are easily predictable
+or are simply the machine's MAC address (which is trivially known to all
+other hosts in the same L2).  This implies that other machines in the L2
+domain can spoof LACPDU packets from other hosts to the switch and potentially
+cause mayhem by joining (from the point of view of the switch) another
+machine's aggregate, thus receiving a portion of that hosts incoming
+traffic and / or spoofing traffic from that machine themselves (potentially
+even successfully terminating some portion of flows). Though this is not
+a likely scenario, one could avoid this possibility by simply configuring
+few bonding parameters:
+
+   (a) ad_actor_system : You can set a random mac-address that can be used for
+       these LACPDU exchanges. The value can not be either NULL or Multicast.
+       Also it's preferable to set the local-admin bit. Following shell code
+       generates a random mac-address as described above::
+
+	      # sys_mac_addr=$(printf '%02x:%02x:%02x:%02x:%02x:%02x' \
+				       $(( (RANDOM & 0xFE) | 0x02 )) \
+				       $(( RANDOM & 0xFF )) \
+				       $(( RANDOM & 0xFF )) \
+				       $(( RANDOM & 0xFF )) \
+				       $(( RANDOM & 0xFF )) \
+				       $(( RANDOM & 0xFF )))
+	      # echo $sys_mac_addr > /sys/class/net/bond0/bonding/ad_actor_system
+
+   (b) ad_actor_sys_prio : Randomize the system priority. The default value
+       is 65535, but system can take the value from 1 - 65535. Following shell
+       code generates random priority and sets it::
+
+	    # sys_prio=$(( 1 + RANDOM + RANDOM ))
+	    # echo $sys_prio > /sys/class/net/bond0/bonding/ad_actor_sys_prio
+
+   (c) ad_user_port_key : Use the user portion of the port-key. The default
+       keeps this empty. These are the upper 10 bits of the port-key and value
+       ranges from 0 - 1023. Following shell code generates these 10 bits and
+       sets it::
+
+	    # usr_port_key=$(( RANDOM & 0x3FF ))
+	    # echo $usr_port_key > /sys/class/net/bond0/bonding/ad_user_port_key
+
+
+4 Querying Bonding Configuration
+=================================
+
+4.1 Bonding Configuration
+-------------------------
+
+Each bonding device has a read-only file residing in the
+/proc/net/bonding directory.  The file contents include information
+about the bonding configuration, options and state of each slave.
+
+For example, the contents of /proc/net/bonding/bond0 after the
+driver is loaded with parameters of mode=0 and miimon=1000 is
+generally as follows::
+
+	Ethernet Channel Bonding Driver: 2.6.1 (October 29, 2004)
+	Bonding Mode: load balancing (round-robin)
+	Currently Active Slave: eth0
+	MII Status: up
+	MII Polling Interval (ms): 1000
+	Up Delay (ms): 0
+	Down Delay (ms): 0
+
+	Slave Interface: eth1
+	MII Status: up
+	Link Failure Count: 1
+
+	Slave Interface: eth0
+	MII Status: up
+	Link Failure Count: 1
+
+The precise format and contents will change depending upon the
+bonding configuration, state, and version of the bonding driver.
+
+4.2 Network configuration
+-------------------------
+
+The network configuration can be inspected using the ifconfig
+command.  Bonding devices will have the MASTER flag set; Bonding slave
+devices will have the SLAVE flag set.  The ifconfig output does not
+contain information on which slaves are associated with which masters.
+
+In the example below, the bond0 interface is the master
+(MASTER) while eth0 and eth1 are slaves (SLAVE). Notice all slaves of
+bond0 have the same MAC address (HWaddr) as bond0 for all modes except
+TLB and ALB that require a unique MAC address for each slave::
+
+  # /sbin/ifconfig
+  bond0     Link encap:Ethernet  HWaddr 00:C0:F0:1F:37:B4
+	    inet addr:XXX.XXX.XXX.YYY  Bcast:XXX.XXX.XXX.255  Mask:255.255.252.0
+	    UP BROADCAST RUNNING MASTER MULTICAST  MTU:1500  Metric:1
+	    RX packets:7224794 errors:0 dropped:0 overruns:0 frame:0
+	    TX packets:3286647 errors:1 dropped:0 overruns:1 carrier:0
+	    collisions:0 txqueuelen:0
+
+  eth0      Link encap:Ethernet  HWaddr 00:C0:F0:1F:37:B4
+	    UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1
+	    RX packets:3573025 errors:0 dropped:0 overruns:0 frame:0
+	    TX packets:1643167 errors:1 dropped:0 overruns:1 carrier:0
+	    collisions:0 txqueuelen:100
+	    Interrupt:10 Base address:0x1080
+
+  eth1      Link encap:Ethernet  HWaddr 00:C0:F0:1F:37:B4
+	    UP BROADCAST RUNNING SLAVE MULTICAST  MTU:1500  Metric:1
+	    RX packets:3651769 errors:0 dropped:0 overruns:0 frame:0
+	    TX packets:1643480 errors:0 dropped:0 overruns:0 carrier:0
+	    collisions:0 txqueuelen:100
+	    Interrupt:9 Base address:0x1400
+
+5. Switch Configuration
+=======================
+
+For this section, "switch" refers to whatever system the
+bonded devices are directly connected to (i.e., where the other end of
+the cable plugs into).  This may be an actual dedicated switch device,
+or it may be another regular system (e.g., another computer running
+Linux),
+
+The active-backup, balance-tlb and balance-alb modes do not
+require any specific configuration of the switch.
+
+The 802.3ad mode requires that the switch have the appropriate
+ports configured as an 802.3ad aggregation.  The precise method used
+to configure this varies from switch to switch, but, for example, a
+Cisco 3550 series switch requires that the appropriate ports first be
+grouped together in a single etherchannel instance, then that
+etherchannel is set to mode "lacp" to enable 802.3ad (instead of
+standard EtherChannel).
+
+The balance-rr, balance-xor and broadcast modes generally
+require that the switch have the appropriate ports grouped together.
+The nomenclature for such a group differs between switches, it may be
+called an "etherchannel" (as in the Cisco example, above), a "trunk
+group" or some other similar variation.  For these modes, each switch
+will also have its own configuration options for the switch's transmit
+policy to the bond.  Typical choices include XOR of either the MAC or
+IP addresses.  The transmit policy of the two peers does not need to
+match.  For these three modes, the bonding mode really selects a
+transmit policy for an EtherChannel group; all three will interoperate
+with another EtherChannel group.
+
+
+6. 802.1q VLAN Support
+======================
+
+It is possible to configure VLAN devices over a bond interface
+using the 8021q driver.  However, only packets coming from the 8021q
+driver and passing through bonding will be tagged by default.  Self
+generated packets, for example, bonding's learning packets or ARP
+packets generated by either ALB mode or the ARP monitor mechanism, are
+tagged internally by bonding itself.  As a result, bonding must
+"learn" the VLAN IDs configured above it, and use those IDs to tag
+self generated packets.
+
+For reasons of simplicity, and to support the use of adapters
+that can do VLAN hardware acceleration offloading, the bonding
+interface declares itself as fully hardware offloading capable, it gets
+the add_vid/kill_vid notifications to gather the necessary
+information, and it propagates those actions to the slaves.  In case
+of mixed adapter types, hardware accelerated tagged packets that
+should go through an adapter that is not offloading capable are
+"un-accelerated" by the bonding driver so the VLAN tag sits in the
+regular location.
+
+VLAN interfaces *must* be added on top of a bonding interface
+only after enslaving at least one slave.  The bonding interface has a
+hardware address of 00:00:00:00:00:00 until the first slave is added.
+If the VLAN interface is created prior to the first enslavement, it
+would pick up the all-zeroes hardware address.  Once the first slave
+is attached to the bond, the bond device itself will pick up the
+slave's hardware address, which is then available for the VLAN device.
+
+Also, be aware that a similar problem can occur if all slaves
+are released from a bond that still has one or more VLAN interfaces on
+top of it.  When a new slave is added, the bonding interface will
+obtain its hardware address from the first slave, which might not
+match the hardware address of the VLAN interfaces (which was
+ultimately copied from an earlier slave).
+
+There are two methods to insure that the VLAN device operates
+with the correct hardware address if all slaves are removed from a
+bond interface:
+
+1. Remove all VLAN interfaces then recreate them
+
+2. Set the bonding interface's hardware address so that it
+matches the hardware address of the VLAN interfaces.
+
+Note that changing a VLAN interface's HW address would set the
+underlying device -- i.e. the bonding interface -- to promiscuous
+mode, which might not be what you want.
+
+
+7. Link Monitoring
+==================
+
+The bonding driver at present supports two schemes for
+monitoring a slave device's link state: the ARP monitor and the MII
+monitor.
+
+At the present time, due to implementation restrictions in the
+bonding driver itself, it is not possible to enable both ARP and MII
+monitoring simultaneously.
+
+7.1 ARP Monitor Operation
+-------------------------
+
+The ARP monitor operates as its name suggests: it sends ARP
+queries to one or more designated peer systems on the network, and
+uses the response as an indication that the link is operating.  This
+gives some assurance that traffic is actually flowing to and from one
+or more peers on the local network.
+
+The ARP monitor relies on the device driver itself to verify
+that traffic is flowing.  In particular, the driver must keep up to
+date the last receive time, dev->last_rx.  Drivers that use NETIF_F_LLTX
+flag must also update netdev_queue->trans_start.  If they do not, then the
+ARP monitor will immediately fail any slaves using that driver, and
+those slaves will stay down.  If networking monitoring (tcpdump, etc)
+shows the ARP requests and replies on the network, then it may be that
+your device driver is not updating last_rx and trans_start.
+
+7.2 Configuring Multiple ARP Targets
+------------------------------------
+
+While ARP monitoring can be done with just one target, it can
+be useful in a High Availability setup to have several targets to
+monitor.  In the case of just one target, the target itself may go
+down or have a problem making it unresponsive to ARP requests.  Having
+an additional target (or several) increases the reliability of the ARP
+monitoring.
+
+Multiple ARP targets must be separated by commas as follows::
+
+ # example options for ARP monitoring with three targets
+ alias bond0 bonding
+ options bond0 arp_interval=60 arp_ip_target=192.168.0.1,192.168.0.3,192.168.0.9
+
+For just a single target the options would resemble::
+
+    # example options for ARP monitoring with one target
+    alias bond0 bonding
+    options bond0 arp_interval=60 arp_ip_target=192.168.0.100
+
+
+7.3 MII Monitor Operation
+-------------------------
+
+The MII monitor monitors only the carrier state of the local
+network interface.  It accomplishes this in one of three ways: by
+depending upon the device driver to maintain its carrier state, by
+querying the device's MII registers, or by making an ethtool query to
+the device.
+
+If the use_carrier module parameter is 1 (the default value),
+then the MII monitor will rely on the driver for carrier state
+information (via the netif_carrier subsystem).  As explained in the
+use_carrier parameter information, above, if the MII monitor fails to
+detect carrier loss on the device (e.g., when the cable is physically
+disconnected), it may be that the driver does not support
+netif_carrier.
+
+If use_carrier is 0, then the MII monitor will first query the
+device's (via ioctl) MII registers and check the link state.  If that
+request fails (not just that it returns carrier down), then the MII
+monitor will make an ethtool ETHOOL_GLINK request to attempt to obtain
+the same information.  If both methods fail (i.e., the driver either
+does not support or had some error in processing both the MII register
+and ethtool requests), then the MII monitor will assume the link is
+up.
+
+8. Potential Sources of Trouble
+===============================
+
+8.1 Adventures in Routing
+-------------------------
+
+When bonding is configured, it is important that the slave
+devices not have routes that supersede routes of the master (or,
+generally, not have routes at all).  For example, suppose the bonding
+device bond0 has two slaves, eth0 and eth1, and the routing table is
+as follows::
+
+  Kernel IP routing table
+  Destination     Gateway         Genmask         Flags   MSS Window  irtt Iface
+  10.0.0.0        0.0.0.0         255.255.0.0     U        40 0          0 eth0
+  10.0.0.0        0.0.0.0         255.255.0.0     U        40 0          0 eth1
+  10.0.0.0        0.0.0.0         255.255.0.0     U        40 0          0 bond0
+  127.0.0.0       0.0.0.0         255.0.0.0       U        40 0          0 lo
+
+This routing configuration will likely still update the
+receive/transmit times in the driver (needed by the ARP monitor), but
+may bypass the bonding driver (because outgoing traffic to, in this
+case, another host on network 10 would use eth0 or eth1 before bond0).
+
+The ARP monitor (and ARP itself) may become confused by this
+configuration, because ARP requests (generated by the ARP monitor)
+will be sent on one interface (bond0), but the corresponding reply
+will arrive on a different interface (eth0).  This reply looks to ARP
+as an unsolicited ARP reply (because ARP matches replies on an
+interface basis), and is discarded.  The MII monitor is not affected
+by the state of the routing table.
+
+The solution here is simply to insure that slaves do not have
+routes of their own, and if for some reason they must, those routes do
+not supersede routes of their master.  This should generally be the
+case, but unusual configurations or errant manual or automatic static
+route additions may cause trouble.
+
+8.2 Ethernet Device Renaming
+----------------------------
+
+On systems with network configuration scripts that do not
+associate physical devices directly with network interface names (so
+that the same physical device always has the same "ethX" name), it may
+be necessary to add some special logic to config files in
+/etc/modprobe.d/.
+
+For example, given a modules.conf containing the following::
+
+	alias bond0 bonding
+	options bond0 mode=some-mode miimon=50
+	alias eth0 tg3
+	alias eth1 tg3
+	alias eth2 e1000
+	alias eth3 e1000
+
+If neither eth0 and eth1 are slaves to bond0, then when the
+bond0 interface comes up, the devices may end up reordered.  This
+happens because bonding is loaded first, then its slave device's
+drivers are loaded next.  Since no other drivers have been loaded,
+when the e1000 driver loads, it will receive eth0 and eth1 for its
+devices, but the bonding configuration tries to enslave eth2 and eth3
+(which may later be assigned to the tg3 devices).
+
+Adding the following::
+
+	add above bonding e1000 tg3
+
+causes modprobe to load e1000 then tg3, in that order, when
+bonding is loaded.  This command is fully documented in the
+modules.conf manual page.
+
+On systems utilizing modprobe an equivalent problem can occur.
+In this case, the following can be added to config files in
+/etc/modprobe.d/ as::
+
+	softdep bonding pre: tg3 e1000
+
+This will load tg3 and e1000 modules before loading the bonding one.
+Full documentation on this can be found in the modprobe.d and modprobe
+manual pages.
+
+8.3. Painfully Slow Or No Failed Link Detection By Miimon
+---------------------------------------------------------
+
+By default, bonding enables the use_carrier option, which
+instructs bonding to trust the driver to maintain carrier state.
+
+As discussed in the options section, above, some drivers do
+not support the netif_carrier_on/_off link state tracking system.
+With use_carrier enabled, bonding will always see these links as up,
+regardless of their actual state.
+
+Additionally, other drivers do support netif_carrier, but do
+not maintain it in real time, e.g., only polling the link state at
+some fixed interval.  In this case, miimon will detect failures, but
+only after some long period of time has expired.  If it appears that
+miimon is very slow in detecting link failures, try specifying
+use_carrier=0 to see if that improves the failure detection time.  If
+it does, then it may be that the driver checks the carrier state at a
+fixed interval, but does not cache the MII register values (so the
+use_carrier=0 method of querying the registers directly works).  If
+use_carrier=0 does not improve the failover, then the driver may cache
+the registers, or the problem may be elsewhere.
+
+Also, remember that miimon only checks for the device's
+carrier state.  It has no way to determine the state of devices on or
+beyond other ports of a switch, or if a switch is refusing to pass
+traffic while still maintaining carrier on.
+
+9. SNMP agents
+===============
+
+If running SNMP agents, the bonding driver should be loaded
+before any network drivers participating in a bond.  This requirement
+is due to the interface index (ipAdEntIfIndex) being associated to
+the first interface found with a given IP address.  That is, there is
+only one ipAdEntIfIndex for each IP address.  For example, if eth0 and
+eth1 are slaves of bond0 and the driver for eth0 is loaded before the
+bonding driver, the interface for the IP address will be associated
+with the eth0 interface.  This configuration is shown below, the IP
+address 192.168.1.1 has an interface index of 2 which indexes to eth0
+in the ifDescr table (ifDescr.2).
+
+::
+
+     interfaces.ifTable.ifEntry.ifDescr.1 = lo
+     interfaces.ifTable.ifEntry.ifDescr.2 = eth0
+     interfaces.ifTable.ifEntry.ifDescr.3 = eth1
+     interfaces.ifTable.ifEntry.ifDescr.4 = eth2
+     interfaces.ifTable.ifEntry.ifDescr.5 = eth3
+     interfaces.ifTable.ifEntry.ifDescr.6 = bond0
+     ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 5
+     ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2
+     ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 4
+     ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1
+
+This problem is avoided by loading the bonding driver before
+any network drivers participating in a bond.  Below is an example of
+loading the bonding driver first, the IP address 192.168.1.1 is
+correctly associated with ifDescr.2.
+
+     interfaces.ifTable.ifEntry.ifDescr.1 = lo
+     interfaces.ifTable.ifEntry.ifDescr.2 = bond0
+     interfaces.ifTable.ifEntry.ifDescr.3 = eth0
+     interfaces.ifTable.ifEntry.ifDescr.4 = eth1
+     interfaces.ifTable.ifEntry.ifDescr.5 = eth2
+     interfaces.ifTable.ifEntry.ifDescr.6 = eth3
+     ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.10.10.10 = 6
+     ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.192.168.1.1 = 2
+     ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.10.74.20.94 = 5
+     ip.ipAddrTable.ipAddrEntry.ipAdEntIfIndex.127.0.0.1 = 1
+
+While some distributions may not report the interface name in
+ifDescr, the association between the IP address and IfIndex remains
+and SNMP functions such as Interface_Scan_Next will report that
+association.
+
+10. Promiscuous mode
+====================
+
+When running network monitoring tools, e.g., tcpdump, it is
+common to enable promiscuous mode on the device, so that all traffic
+is seen (instead of seeing only traffic destined for the local host).
+The bonding driver handles promiscuous mode changes to the bonding
+master device (e.g., bond0), and propagates the setting to the slave
+devices.
+
+For the balance-rr, balance-xor, broadcast, and 802.3ad modes,
+the promiscuous mode setting is propagated to all slaves.
+
+For the active-backup, balance-tlb and balance-alb modes, the
+promiscuous mode setting is propagated only to the active slave.
+
+For balance-tlb mode, the active slave is the slave currently
+receiving inbound traffic.
+
+For balance-alb mode, the active slave is the slave used as a
+"primary."  This slave is used for mode-specific control traffic, for
+sending to peers that are unassigned or if the load is unbalanced.
+
+For the active-backup, balance-tlb and balance-alb modes, when
+the active slave changes (e.g., due to a link failure), the
+promiscuous setting will be propagated to the new active slave.
+
+11. Configuring Bonding for High Availability
+=============================================
+
+High Availability refers to configurations that provide
+maximum network availability by having redundant or backup devices,
+links or switches between the host and the rest of the world.  The
+goal is to provide the maximum availability of network connectivity
+(i.e., the network always works), even though other configurations
+could provide higher throughput.
+
+11.1 High Availability in a Single Switch Topology
+--------------------------------------------------
+
+If two hosts (or a host and a single switch) are directly
+connected via multiple physical links, then there is no availability
+penalty to optimizing for maximum bandwidth.  In this case, there is
+only one switch (or peer), so if it fails, there is no alternative
+access to fail over to.  Additionally, the bonding load balance modes
+support link monitoring of their members, so if individual links fail,
+the load will be rebalanced across the remaining devices.
+
+See Section 12, "Configuring Bonding for Maximum Throughput"
+for information on configuring bonding with one peer device.
+
+11.2 High Availability in a Multiple Switch Topology
+----------------------------------------------------
+
+With multiple switches, the configuration of bonding and the
+network changes dramatically.  In multiple switch topologies, there is
+a trade off between network availability and usable bandwidth.
+
+Below is a sample network, configured to maximize the
+availability of the network::
+
+		|                                     |
+		|port3                           port3|
+	  +-----+----+                          +-----+----+
+	  |          |port2       ISL      port2|          |
+	  | switch A +--------------------------+ switch B |
+	  |          |                          |          |
+	  +-----+----+                          +-----++---+
+		|port1                           port1|
+		|             +-------+               |
+		+-------------+ host1 +---------------+
+			 eth0 +-------+ eth1
+
+In this configuration, there is a link between the two
+switches (ISL, or inter switch link), and multiple ports connecting to
+the outside world ("port3" on each switch).  There is no technical
+reason that this could not be extended to a third switch.
+
+11.2.1 HA Bonding Mode Selection for Multiple Switch Topology
+-------------------------------------------------------------
+
+In a topology such as the example above, the active-backup and
+broadcast modes are the only useful bonding modes when optimizing for
+availability; the other modes require all links to terminate on the
+same peer for them to behave rationally.
+
+active-backup:
+	This is generally the preferred mode, particularly if
+	the switches have an ISL and play together well.  If the
+	network configuration is such that one switch is specifically
+	a backup switch (e.g., has lower capacity, higher cost, etc),
+	then the primary option can be used to insure that the
+	preferred link is always used when it is available.
+
+broadcast:
+	This mode is really a special purpose mode, and is suitable
+	only for very specific needs.  For example, if the two
+	switches are not connected (no ISL), and the networks beyond
+	them are totally independent.  In this case, if it is
+	necessary for some specific one-way traffic to reach both
+	independent networks, then the broadcast mode may be suitable.
+
+11.2.2 HA Link Monitoring Selection for Multiple Switch Topology
+----------------------------------------------------------------
+
+The choice of link monitoring ultimately depends upon your
+switch.  If the switch can reliably fail ports in response to other
+failures, then either the MII or ARP monitors should work.  For
+example, in the above example, if the "port3" link fails at the remote
+end, the MII monitor has no direct means to detect this.  The ARP
+monitor could be configured with a target at the remote end of port3,
+thus detecting that failure without switch support.
+
+In general, however, in a multiple switch topology, the ARP
+monitor can provide a higher level of reliability in detecting end to
+end connectivity failures (which may be caused by the failure of any
+individual component to pass traffic for any reason).  Additionally,
+the ARP monitor should be configured with multiple targets (at least
+one for each switch in the network).  This will insure that,
+regardless of which switch is active, the ARP monitor has a suitable
+target to query.
+
+Note, also, that of late many switches now support a functionality
+generally referred to as "trunk failover."  This is a feature of the
+switch that causes the link state of a particular switch port to be set
+down (or up) when the state of another switch port goes down (or up).
+Its purpose is to propagate link failures from logically "exterior" ports
+to the logically "interior" ports that bonding is able to monitor via
+miimon.  Availability and configuration for trunk failover varies by
+switch, but this can be a viable alternative to the ARP monitor when using
+suitable switches.
+
+12. Configuring Bonding for Maximum Throughput
+==============================================
+
+12.1 Maximizing Throughput in a Single Switch Topology
+------------------------------------------------------
+
+In a single switch configuration, the best method to maximize
+throughput depends upon the application and network environment.  The
+various load balancing modes each have strengths and weaknesses in
+different environments, as detailed below.
+
+For this discussion, we will break down the topologies into
+two categories.  Depending upon the destination of most traffic, we
+categorize them into either "gatewayed" or "local" configurations.
+
+In a gatewayed configuration, the "switch" is acting primarily
+as a router, and the majority of traffic passes through this router to
+other networks.  An example would be the following::
+
+
+     +----------+                     +----------+
+     |          |eth0            port1|          | to other networks
+     | Host A   +---------------------+ router   +------------------->
+     |          +---------------------+          | Hosts B and C are out
+     |          |eth1            port2|          | here somewhere
+     +----------+                     +----------+
+
+The router may be a dedicated router device, or another host
+acting as a gateway.  For our discussion, the important point is that
+the majority of traffic from Host A will pass through the router to
+some other network before reaching its final destination.
+
+In a gatewayed network configuration, although Host A may
+communicate with many other systems, all of its traffic will be sent
+and received via one other peer on the local network, the router.
+
+Note that the case of two systems connected directly via
+multiple physical links is, for purposes of configuring bonding, the
+same as a gatewayed configuration.  In that case, it happens that all
+traffic is destined for the "gateway" itself, not some other network
+beyond the gateway.
+
+In a local configuration, the "switch" is acting primarily as
+a switch, and the majority of traffic passes through this switch to
+reach other stations on the same network.  An example would be the
+following::
+
+    +----------+            +----------+       +--------+
+    |          |eth0   port1|          +-------+ Host B |
+    |  Host A  +------------+  switch  |port3  +--------+
+    |          +------------+          |                  +--------+
+    |          |eth1   port2|          +------------------+ Host C |
+    +----------+            +----------+port4             +--------+
+
+
+Again, the switch may be a dedicated switch device, or another
+host acting as a gateway.  For our discussion, the important point is
+that the majority of traffic from Host A is destined for other hosts
+on the same local network (Hosts B and C in the above example).
+
+In summary, in a gatewayed configuration, traffic to and from
+the bonded device will be to the same MAC level peer on the network
+(the gateway itself, i.e., the router), regardless of its final
+destination.  In a local configuration, traffic flows directly to and
+from the final destinations, thus, each destination (Host B, Host C)
+will be addressed directly by their individual MAC addresses.
+
+This distinction between a gatewayed and a local network
+configuration is important because many of the load balancing modes
+available use the MAC addresses of the local network source and
+destination to make load balancing decisions.  The behavior of each
+mode is described below.
+
+
+12.1.1 MT Bonding Mode Selection for Single Switch Topology
+-----------------------------------------------------------
+
+This configuration is the easiest to set up and to understand,
+although you will have to decide which bonding mode best suits your
+needs.  The trade offs for each mode are detailed below:
+
+balance-rr:
+	This mode is the only mode that will permit a single
+	TCP/IP connection to stripe traffic across multiple
+	interfaces. It is therefore the only mode that will allow a
+	single TCP/IP stream to utilize more than one interface's
+	worth of throughput.  This comes at a cost, however: the
+	striping generally results in peer systems receiving packets out
+	of order, causing TCP/IP's congestion control system to kick
+	in, often by retransmitting segments.
+
+	It is possible to adjust TCP/IP's congestion limits by
+	altering the net.ipv4.tcp_reordering sysctl parameter.  The
+	usual default value is 3. But keep in mind TCP stack is able
+	to automatically increase this when it detects reorders.
+
+	Note that the fraction of packets that will be delivered out of
+	order is highly variable, and is unlikely to be zero.  The level
+	of reordering depends upon a variety of factors, including the
+	networking interfaces, the switch, and the topology of the
+	configuration.  Speaking in general terms, higher speed network
+	cards produce more reordering (due to factors such as packet
+	coalescing), and a "many to many" topology will reorder at a
+	higher rate than a "many slow to one fast" configuration.
+
+	Many switches do not support any modes that stripe traffic
+	(instead choosing a port based upon IP or MAC level addresses);
+	for those devices, traffic for a particular connection flowing
+	through the switch to a balance-rr bond will not utilize greater
+	than one interface's worth of bandwidth.
+
+	If you are utilizing protocols other than TCP/IP, UDP for
+	example, and your application can tolerate out of order
+	delivery, then this mode can allow for single stream datagram
+	performance that scales near linearly as interfaces are added
+	to the bond.
+
+	This mode requires the switch to have the appropriate ports
+	configured for "etherchannel" or "trunking."
+
+active-backup:
+	There is not much advantage in this network topology to
+	the active-backup mode, as the inactive backup devices are all
+	connected to the same peer as the primary.  In this case, a
+	load balancing mode (with link monitoring) will provide the
+	same level of network availability, but with increased
+	available bandwidth.  On the plus side, active-backup mode
+	does not require any configuration of the switch, so it may
+	have value if the hardware available does not support any of
+	the load balance modes.
+
+balance-xor:
+	This mode will limit traffic such that packets destined
+	for specific peers will always be sent over the same
+	interface.  Since the destination is determined by the MAC
+	addresses involved, this mode works best in a "local" network
+	configuration (as described above), with destinations all on
+	the same local network.  This mode is likely to be suboptimal
+	if all your traffic is passed through a single router (i.e., a
+	"gatewayed" network configuration, as described above).
+
+	As with balance-rr, the switch ports need to be configured for
+	"etherchannel" or "trunking."
+
+broadcast:
+	Like active-backup, there is not much advantage to this
+	mode in this type of network topology.
+
+802.3ad:
+	This mode can be a good choice for this type of network
+	topology.  The 802.3ad mode is an IEEE standard, so all peers
+	that implement 802.3ad should interoperate well.  The 802.3ad
+	protocol includes automatic configuration of the aggregates,
+	so minimal manual configuration of the switch is needed
+	(typically only to designate that some set of devices is
+	available for 802.3ad).  The 802.3ad standard also mandates
+	that frames be delivered in order (within certain limits), so
+	in general single connections will not see misordering of
+	packets.  The 802.3ad mode does have some drawbacks: the
+	standard mandates that all devices in the aggregate operate at
+	the same speed and duplex.  Also, as with all bonding load
+	balance modes other than balance-rr, no single connection will
+	be able to utilize more than a single interface's worth of
+	bandwidth.
+
+	Additionally, the linux bonding 802.3ad implementation
+	distributes traffic by peer (using an XOR of MAC addresses
+	and packet type ID), so in a "gatewayed" configuration, all
+	outgoing traffic will generally use the same device.  Incoming
+	traffic may also end up on a single device, but that is
+	dependent upon the balancing policy of the peer's 802.3ad
+	implementation.  In a "local" configuration, traffic will be
+	distributed across the devices in the bond.
+
+	Finally, the 802.3ad mode mandates the use of the MII monitor,
+	therefore, the ARP monitor is not available in this mode.
+
+balance-tlb:
+	The balance-tlb mode balances outgoing traffic by peer.
+	Since the balancing is done according to MAC address, in a
+	"gatewayed" configuration (as described above), this mode will
+	send all traffic across a single device.  However, in a
+	"local" network configuration, this mode balances multiple
+	local network peers across devices in a vaguely intelligent
+	manner (not a simple XOR as in balance-xor or 802.3ad mode),
+	so that mathematically unlucky MAC addresses (i.e., ones that
+	XOR to the same value) will not all "bunch up" on a single
+	interface.
+
+	Unlike 802.3ad, interfaces may be of differing speeds, and no
+	special switch configuration is required.  On the down side,
+	in this mode all incoming traffic arrives over a single
+	interface, this mode requires certain ethtool support in the
+	network device driver of the slave interfaces, and the ARP
+	monitor is not available.
+
+balance-alb:
+	This mode is everything that balance-tlb is, and more.
+	It has all of the features (and restrictions) of balance-tlb,
+	and will also balance incoming traffic from local network
+	peers (as described in the Bonding Module Options section,
+	above).
+
+	The only additional down side to this mode is that the network
+	device driver must support changing the hardware address while
+	the device is open.
+
+12.1.2 MT Link Monitoring for Single Switch Topology
+----------------------------------------------------
+
+The choice of link monitoring may largely depend upon which
+mode you choose to use.  The more advanced load balancing modes do not
+support the use of the ARP monitor, and are thus restricted to using
+the MII monitor (which does not provide as high a level of end to end
+assurance as the ARP monitor).
+
+12.2 Maximum Throughput in a Multiple Switch Topology
+-----------------------------------------------------
+
+Multiple switches may be utilized to optimize for throughput
+when they are configured in parallel as part of an isolated network
+between two or more systems, for example::
+
+		       +-----------+
+		       |  Host A   |
+		       +-+---+---+-+
+			 |   |   |
+		+--------+   |   +---------+
+		|            |             |
+	 +------+---+  +-----+----+  +-----+----+
+	 | Switch A |  | Switch B |  | Switch C |
+	 +------+---+  +-----+----+  +-----+----+
+		|            |             |
+		+--------+   |   +---------+
+			 |   |   |
+		       +-+---+---+-+
+		       |  Host B   |
+		       +-----------+
+
+In this configuration, the switches are isolated from one
+another.  One reason to employ a topology such as this is for an
+isolated network with many hosts (a cluster configured for high
+performance, for example), using multiple smaller switches can be more
+cost effective than a single larger switch, e.g., on a network with 24
+hosts, three 24 port switches can be significantly less expensive than
+a single 72 port switch.
+
+If access beyond the network is required, an individual host
+can be equipped with an additional network device connected to an
+external network; this host then additionally acts as a gateway.
+
+12.2.1 MT Bonding Mode Selection for Multiple Switch Topology
+-------------------------------------------------------------
+
+In actual practice, the bonding mode typically employed in
+configurations of this type is balance-rr.  Historically, in this
+network configuration, the usual caveats about out of order packet
+delivery are mitigated by the use of network adapters that do not do
+any kind of packet coalescing (via the use of NAPI, or because the
+device itself does not generate interrupts until some number of
+packets has arrived).  When employed in this fashion, the balance-rr
+mode allows individual connections between two hosts to effectively
+utilize greater than one interface's bandwidth.
+
+12.2.2 MT Link Monitoring for Multiple Switch Topology
+------------------------------------------------------
+
+Again, in actual practice, the MII monitor is most often used
+in this configuration, as performance is given preference over
+availability.  The ARP monitor will function in this topology, but its
+advantages over the MII monitor are mitigated by the volume of probes
+needed as the number of systems involved grows (remember that each
+host in the network is configured with bonding).
+
+13. Switch Behavior Issues
+==========================
+
+13.1 Link Establishment and Failover Delays
+-------------------------------------------
+
+Some switches exhibit undesirable behavior with regard to the
+timing of link up and down reporting by the switch.
+
+First, when a link comes up, some switches may indicate that
+the link is up (carrier available), but not pass traffic over the
+interface for some period of time.  This delay is typically due to
+some type of autonegotiation or routing protocol, but may also occur
+during switch initialization (e.g., during recovery after a switch
+failure).  If you find this to be a problem, specify an appropriate
+value to the updelay bonding module option to delay the use of the
+relevant interface(s).
+
+Second, some switches may "bounce" the link state one or more
+times while a link is changing state.  This occurs most commonly while
+the switch is initializing.  Again, an appropriate updelay value may
+help.
+
+Note that when a bonding interface has no active links, the
+driver will immediately reuse the first link that goes up, even if the
+updelay parameter has been specified (the updelay is ignored in this
+case).  If there are slave interfaces waiting for the updelay timeout
+to expire, the interface that first went into that state will be
+immediately reused.  This reduces down time of the network if the
+value of updelay has been overestimated, and since this occurs only in
+cases with no connectivity, there is no additional penalty for
+ignoring the updelay.
+
+In addition to the concerns about switch timings, if your
+switches take a long time to go into backup mode, it may be desirable
+to not activate a backup interface immediately after a link goes down.
+Failover may be delayed via the downdelay bonding module option.
+
+13.2 Duplicated Incoming Packets
+--------------------------------
+
+NOTE: Starting with version 3.0.2, the bonding driver has logic to
+suppress duplicate packets, which should largely eliminate this problem.
+The following description is kept for reference.
+
+It is not uncommon to observe a short burst of duplicated
+traffic when the bonding device is first used, or after it has been
+idle for some period of time.  This is most easily observed by issuing
+a "ping" to some other host on the network, and noticing that the
+output from ping flags duplicates (typically one per slave).
+
+For example, on a bond in active-backup mode with five slaves
+all connected to one switch, the output may appear as follows::
+
+	# ping -n 10.0.4.2
+	PING 10.0.4.2 (10.0.4.2) from 10.0.3.10 : 56(84) bytes of data.
+	64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.7 ms
+	64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
+	64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
+	64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
+	64 bytes from 10.0.4.2: icmp_seq=1 ttl=64 time=13.8 ms (DUP!)
+	64 bytes from 10.0.4.2: icmp_seq=2 ttl=64 time=0.216 ms
+	64 bytes from 10.0.4.2: icmp_seq=3 ttl=64 time=0.267 ms
+	64 bytes from 10.0.4.2: icmp_seq=4 ttl=64 time=0.222 ms
+
+This is not due to an error in the bonding driver, rather, it
+is a side effect of how many switches update their MAC forwarding
+tables.  Initially, the switch does not associate the MAC address in
+the packet with a particular switch port, and so it may send the
+traffic to all ports until its MAC forwarding table is updated.  Since
+the interfaces attached to the bond may occupy multiple ports on a
+single switch, when the switch (temporarily) floods the traffic to all
+ports, the bond device receives multiple copies of the same packet
+(one per slave device).
+
+The duplicated packet behavior is switch dependent, some
+switches exhibit this, and some do not.  On switches that display this
+behavior, it can be induced by clearing the MAC forwarding table (on
+most Cisco switches, the privileged command "clear mac address-table
+dynamic" will accomplish this).
+
+14. Hardware Specific Considerations
+====================================
+
+This section contains additional information for configuring
+bonding on specific hardware platforms, or for interfacing bonding
+with particular switches or other devices.
+
+14.1 IBM BladeCenter
+--------------------
+
+This applies to the JS20 and similar systems.
+
+On the JS20 blades, the bonding driver supports only
+balance-rr, active-backup, balance-tlb and balance-alb modes.  This is
+largely due to the network topology inside the BladeCenter, detailed
+below.
+
+JS20 network adapter information
+--------------------------------
+
+All JS20s come with two Broadcom Gigabit Ethernet ports
+integrated on the planar (that's "motherboard" in IBM-speak).  In the
+BladeCenter chassis, the eth0 port of all JS20 blades is hard wired to
+I/O Module #1; similarly, all eth1 ports are wired to I/O Module #2.
+An add-on Broadcom daughter card can be installed on a JS20 to provide
+two more Gigabit Ethernet ports.  These ports, eth2 and eth3, are
+wired to I/O Modules 3 and 4, respectively.
+
+Each I/O Module may contain either a switch or a passthrough
+module (which allows ports to be directly connected to an external
+switch).  Some bonding modes require a specific BladeCenter internal
+network topology in order to function; these are detailed below.
+
+Additional BladeCenter-specific networking information can be
+found in two IBM Redbooks (www.ibm.com/redbooks):
+
+- "IBM eServer BladeCenter Networking Options"
+- "IBM eServer BladeCenter Layer 2-7 Network Switching"
+
+BladeCenter networking configuration
+------------------------------------
+
+Because a BladeCenter can be configured in a very large number
+of ways, this discussion will be confined to describing basic
+configurations.
+
+Normally, Ethernet Switch Modules (ESMs) are used in I/O
+modules 1 and 2.  In this configuration, the eth0 and eth1 ports of a
+JS20 will be connected to different internal switches (in the
+respective I/O modules).
+
+A passthrough module (OPM or CPM, optical or copper,
+passthrough module) connects the I/O module directly to an external
+switch.  By using PMs in I/O module #1 and #2, the eth0 and eth1
+interfaces of a JS20 can be redirected to the outside world and
+connected to a common external switch.
+
+Depending upon the mix of ESMs and PMs, the network will
+appear to bonding as either a single switch topology (all PMs) or as a
+multiple switch topology (one or more ESMs, zero or more PMs).  It is
+also possible to connect ESMs together, resulting in a configuration
+much like the example in "High Availability in a Multiple Switch
+Topology," above.
+
+Requirements for specific modes
+-------------------------------
+
+The balance-rr mode requires the use of passthrough modules
+for devices in the bond, all connected to an common external switch.
+That switch must be configured for "etherchannel" or "trunking" on the
+appropriate ports, as is usual for balance-rr.
+
+The balance-alb and balance-tlb modes will function with
+either switch modules or passthrough modules (or a mix).  The only
+specific requirement for these modes is that all network interfaces
+must be able to reach all destinations for traffic sent over the
+bonding device (i.e., the network must converge at some point outside
+the BladeCenter).
+
+The active-backup mode has no additional requirements.
+
+Link monitoring issues
+----------------------
+
+When an Ethernet Switch Module is in place, only the ARP
+monitor will reliably detect link loss to an external switch.  This is
+nothing unusual, but examination of the BladeCenter cabinet would
+suggest that the "external" network ports are the ethernet ports for
+the system, when it fact there is a switch between these "external"
+ports and the devices on the JS20 system itself.  The MII monitor is
+only able to detect link failures between the ESM and the JS20 system.
+
+When a passthrough module is in place, the MII monitor does
+detect failures to the "external" port, which is then directly
+connected to the JS20 system.
+
+Other concerns
+--------------
+
+The Serial Over LAN (SoL) link is established over the primary
+ethernet (eth0) only, therefore, any loss of link to eth0 will result
+in losing your SoL connection.  It will not fail over with other
+network traffic, as the SoL system is beyond the control of the
+bonding driver.
+
+It may be desirable to disable spanning tree on the switch
+(either the internal Ethernet Switch Module, or an external switch) to
+avoid fail-over delay issues when using bonding.
+
+
+15. Frequently Asked Questions
+==============================
+
+1.  Is it SMP safe?
+-------------------
+
+Yes. The old 2.0.xx channel bonding patch was not SMP safe.
+The new driver was designed to be SMP safe from the start.
+
+2.  What type of cards will work with it?
+-----------------------------------------
+
+Any Ethernet type cards (you can even mix cards - a Intel
+EtherExpress PRO/100 and a 3com 3c905b, for example).  For most modes,
+devices need not be of the same speed.
+
+Starting with version 3.2.1, bonding also supports Infiniband
+slaves in active-backup mode.
+
+3.  How many bonding devices can I have?
+----------------------------------------
+
+There is no limit.
+
+4.  How many slaves can a bonding device have?
+----------------------------------------------
+
+This is limited only by the number of network interfaces Linux
+supports and/or the number of network cards you can place in your
+system.
+
+5.  What happens when a slave link dies?
+----------------------------------------
+
+If link monitoring is enabled, then the failing device will be
+disabled.  The active-backup mode will fail over to a backup link, and
+other modes will ignore the failed link.  The link will continue to be
+monitored, and should it recover, it will rejoin the bond (in whatever
+manner is appropriate for the mode). See the sections on High
+Availability and the documentation for each mode for additional
+information.
+
+Link monitoring can be enabled via either the miimon or
+arp_interval parameters (described in the module parameters section,
+above).  In general, miimon monitors the carrier state as sensed by
+the underlying network device, and the arp monitor (arp_interval)
+monitors connectivity to another host on the local network.
+
+If no link monitoring is configured, the bonding driver will
+be unable to detect link failures, and will assume that all links are
+always available.  This will likely result in lost packets, and a
+resulting degradation of performance.  The precise performance loss
+depends upon the bonding mode and network configuration.
+
+6.  Can bonding be used for High Availability?
+----------------------------------------------
+
+Yes.  See the section on High Availability for details.
+
+7.  Which switches/systems does it work with?
+---------------------------------------------
+
+The full answer to this depends upon the desired mode.
+
+In the basic balance modes (balance-rr and balance-xor), it
+works with any system that supports etherchannel (also called
+trunking).  Most managed switches currently available have such
+support, and many unmanaged switches as well.
+
+The advanced balance modes (balance-tlb and balance-alb) do
+not have special switch requirements, but do need device drivers that
+support specific features (described in the appropriate section under
+module parameters, above).
+
+In 802.3ad mode, it works with systems that support IEEE
+802.3ad Dynamic Link Aggregation.  Most managed and many unmanaged
+switches currently available support 802.3ad.
+
+The active-backup mode should work with any Layer-II switch.
+
+8.  Where does a bonding device get its MAC address from?
+---------------------------------------------------------
+
+When using slave devices that have fixed MAC addresses, or when
+the fail_over_mac option is enabled, the bonding device's MAC address is
+the MAC address of the active slave.
+
+For other configurations, if not explicitly configured (with
+ifconfig or ip link), the MAC address of the bonding device is taken from
+its first slave device.  This MAC address is then passed to all following
+slaves and remains persistent (even if the first slave is removed) until
+the bonding device is brought down or reconfigured.
+
+If you wish to change the MAC address, you can set it with
+ifconfig or ip link::
+
+	# ifconfig bond0 hw ether 00:11:22:33:44:55
+
+	# ip link set bond0 address 66:77:88:99:aa:bb
+
+The MAC address can be also changed by bringing down/up the
+device and then changing its slaves (or their order)::
+
+	# ifconfig bond0 down ; modprobe -r bonding
+	# ifconfig bond0 .... up
+	# ifenslave bond0 eth...
+
+This method will automatically take the address from the next
+slave that is added.
+
+To restore your slaves' MAC addresses, you need to detach them
+from the bond (``ifenslave -d bond0 eth0``). The bonding driver will
+then restore the MAC addresses that the slaves had before they were
+enslaved.
+
+16. Resources and Links
+=======================
+
+The latest version of the bonding driver can be found in the latest
+version of the linux kernel, found on http://kernel.org
+
+The latest version of this document can be found in the latest kernel
+source (named Documentation/networking/bonding.rst).
+
+Discussions regarding the development of the bonding driver take place
+on the main Linux network mailing list, hosted at vger.kernel.org. The list
+address is:
+
+netdev@vger.kernel.org
+
+The administrative interface (to subscribe or unsubscribe) can
+be found at:
+
+http://vger.kernel.org/vger-lists.html#netdev