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| -rw-r--r-- | Documentation/networking/ipvlan.txt | 146 |
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diff --git a/Documentation/networking/ipvlan.txt b/Documentation/networking/ipvlan.txt new file mode 100644 index 000000000..27a38e50c --- /dev/null +++ b/Documentation/networking/ipvlan.txt @@ -0,0 +1,146 @@ + + IPVLAN Driver HOWTO + +Initial Release: + Mahesh Bandewar <maheshb AT google.com> + +1. Introduction: + This is conceptually very similar to the macvlan driver with one major +exception of using L3 for mux-ing /demux-ing among slaves. This property makes +the master device share the L2 with it's slave devices. I have developed this +driver in conjunction with network namespaces and not sure if there is use case +outside of it. + + +2. Building and Installation: + In order to build the driver, please select the config item CONFIG_IPVLAN. +The driver can be built into the kernel (CONFIG_IPVLAN=y) or as a module +(CONFIG_IPVLAN=m). + + +3. Configuration: + There are no module parameters for this driver and it can be configured +using IProute2/ip utility. + + ip link add link <master> name <slave> type ipvlan [ mode MODE ] [ FLAGS ] + where + MODE: l3 (default) | l3s | l2 + FLAGS: bridge (default) | private | vepa + + e.g. + (a) Following will create IPvlan link with eth0 as master in + L3 bridge mode + bash# ip link add link eth0 name ipvl0 type ipvlan + (b) This command will create IPvlan link in L2 bridge mode. + bash# ip link add link eth0 name ipvl0 type ipvlan mode l2 bridge + (c) This command will create an IPvlan device in L2 private mode. + bash# ip link add link eth0 name ipvlan type ipvlan mode l2 private + (d) This command will create an IPvlan device in L2 vepa mode. + bash# ip link add link eth0 name ipvlan type ipvlan mode l2 vepa + + +4. Operating modes: + IPvlan has two modes of operation - L2 and L3. For a given master device, +you can select one of these two modes and all slaves on that master will +operate in the same (selected) mode. The RX mode is almost identical except +that in L3 mode the slaves wont receive any multicast / broadcast traffic. +L3 mode is more restrictive since routing is controlled from the other (mostly) +default namespace. + +4.1 L2 mode: + In this mode TX processing happens on the stack instance attached to the +slave device and packets are switched and queued to the master device to send +out. In this mode the slaves will RX/TX multicast and broadcast (if applicable) +as well. + +4.2 L3 mode: + In this mode TX processing up to L3 happens on the stack instance attached +to the slave device and packets are switched to the stack instance of the +master device for the L2 processing and routing from that instance will be +used before packets are queued on the outbound device. In this mode the slaves +will not receive nor can send multicast / broadcast traffic. + +4.3 L3S mode: + This is very similar to the L3 mode except that iptables (conn-tracking) +works in this mode and hence it is L3-symmetric (L3s). This will have slightly less +performance but that shouldn't matter since you are choosing this mode over plain-L3 +mode to make conn-tracking work. + +5. Mode flags: + At this time following mode flags are available + +5.1 bridge: + This is the default option. To configure the IPvlan port in this mode, +user can choose to either add this option on the command-line or don't specify +anything. This is the traditional mode where slaves can cross-talk among +themselves apart from talking through the master device. + +5.2 private: + If this option is added to the command-line, the port is set in private +mode. i.e. port won't allow cross communication between slaves. + +5.3 vepa: + If this is added to the command-line, the port is set in VEPA mode. +i.e. port will offload switching functionality to the external entity as +described in 802.1Qbg +Note: VEPA mode in IPvlan has limitations. IPvlan uses the mac-address of the +master-device, so the packets which are emitted in this mode for the adjacent +neighbor will have source and destination mac same. This will make the switch / +router send the redirect message. + +6. What to choose (macvlan vs. ipvlan)? + These two devices are very similar in many regards and the specific use +case could very well define which device to choose. if one of the following +situations defines your use case then you can choose to use ipvlan - + (a) The Linux host that is connected to the external switch / router has +policy configured that allows only one mac per port. + (b) No of virtual devices created on a master exceed the mac capacity and +puts the NIC in promiscuous mode and degraded performance is a concern. + (c) If the slave device is to be put into the hostile / untrusted network +namespace where L2 on the slave could be changed / misused. + + +6. Example configuration: + + +=============================================================+ + | Host: host1 | + | | + | +----------------------+ +----------------------+ | + | | NS:ns0 | | NS:ns1 | | + | | | | | | + | | | | | | + | | ipvl0 | | ipvl1 | | + | +----------#-----------+ +-----------#----------+ | + | # # | + | ################################ | + | # eth0 | + +==============================#==============================+ + + + (a) Create two network namespaces - ns0, ns1 + ip netns add ns0 + ip netns add ns1 + + (b) Create two ipvlan slaves on eth0 (master device) + ip link add link eth0 ipvl0 type ipvlan mode l2 + ip link add link eth0 ipvl1 type ipvlan mode l2 + + (c) Assign slaves to the respective network namespaces + ip link set dev ipvl0 netns ns0 + ip link set dev ipvl1 netns ns1 + + (d) Now switch to the namespace (ns0 or ns1) to configure the slave devices + - For ns0 + (1) ip netns exec ns0 bash + (2) ip link set dev ipvl0 up + (3) ip link set dev lo up + (4) ip -4 addr add 127.0.0.1 dev lo + (5) ip -4 addr add $IPADDR dev ipvl0 + (6) ip -4 route add default via $ROUTER dev ipvl0 + - For ns1 + (1) ip netns exec ns1 bash + (2) ip link set dev ipvl1 up + (3) ip link set dev lo up + (4) ip -4 addr add 127.0.0.1 dev lo + (5) ip -4 addr add $IPADDR dev ipvl1 + (6) ip -4 route add default via $ROUTER dev ipvl1 |