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diff --git a/doc/user/bmp.rst b/doc/user/bmp.rst new file mode 100644 index 0000000..1983995 --- /dev/null +++ b/doc/user/bmp.rst @@ -0,0 +1,166 @@ +.. _bmp: + +*** +BMP +*** + +:abbr:`BMP` (BGP Monitoring Protocol, :rfc:`7854`) is used to send monitoring +data from BGP routers to network management entities. + +Implementation characteristics +============================== + +The `BMP` implementation in FRR has the following properties: + +- only the :rfc:`7854` features are currently implemented. This means protocol + version 3 without any extensions. It is not possible to use an older draft + protocol version of BMP. + +- the following statistics codes are implemented: + + - 0: count of prefixes rejected + - 2: count of duplicate prefix withdrawals + - 3: count of **prefixes** with loop in cluster id + - 4: count of **prefixes** with loop in AS-path + - 5: count of **prefixes** with loop in originator + - 11: count of updates subjected to :rfc:`7607` "treat as withdrawal" + handling due to errors + - 65531: *experimental* count of prefixes rejected due to invalid next-hop + + Note that stat items 3, 4 and 5 are specified to count updates, but FRR + implements them as prefix-based counters. + +- **route mirroring** is fully implemented, however BGP OPEN messages are not + currently included in route mirroring messages. Their contents can be + extracted from the "peer up" notification for sessions that established + successfully. OPEN messages for failed sessions cannot currently be + mirrored. + +- **route monitoring** is available for IPv4 and IPv6 AFIs, unicast and + multicast SAFIs. Other SAFIs (VPN, Labeled-Unicast, Flowspec, etc.) are not + currently supported. + +- monitoring peers that have BGP **add-path** enabled on the session will + result in somewhat unpredictable behaviour. Currently, the outcome is: + + - route mirroring functions as intended, messages are copied verbatim + - the add-path ID is never included in route monitoring messages + - if multiple paths were received from a peer, an unpredictable path is + picked and sent on the BMP session. The selection will differ for + pre-policy and post-policy monitoring sessions. + - as long as any path is present, something will be advertised on BMP + sessions. Only after the last path is gone a withdrawal will be sent on + BMP sessions. + - updates to additional paths will trigger BMP route monitoring messages. + There is no guarantee on consistency regarding which path is sent in these + messages. + +- monitoring peers with :rfc:`5549` extended next-hops has not been tested. + +Starting BMP +============ + +BMP is implemented as a loadable module. This means that to use BMP, ``bgpd`` +must be started with the ``-M bmp`` option. It is not possible to enable BMP +if ``bgpd`` was started without this option. + +Configuring BMP +=============== + +All of FRR's BMP configuration options are located inside the +:clicmd:`router bgp ASN` block. Configure BGP first before proceeding to BMP +setup. + +There is one option that applies to the BGP instance as a whole: + +.. clicmd:: bmp mirror buffer-limit(0-4294967294) + + This sets the maximum amount of memory used for buffering BGP messages + (updates, keepalives, ...) for sending in BMP Route Mirroring. + + The buffer is for the entire BGP instance; if multiple BMP targets are + configured they reference the same buffer and do not consume additional + memory. Queue overhead is included in accounting this memory, so the + actual space available for BGP messages is slightly less than the value + configured here. + + If the buffer fills up, the oldest messages are removed from the buffer and + any BMP sessions where the now-removed messages were still pending have + their **entire** queue flushed and a "Mirroring Messages Lost" BMP message + is sent. + + BMP Route Monitoring is not affected by this option. + +All other configuration is managed per targets: + +.. clicmd:: bmp targets NAME + + Create/delete a targets group. As implied by the plural name, targets may + cover multiple outbound active BMP sessions as well as inbound passive + listeners. + + If BMP sessions have the same configuration, putting them in the same + ``bmp targets`` will reduce overhead. + +BMP session configuration +------------------------- + +Inside a ``bmp targets`` block, the following commands control session +establishment: + + +.. clicmd:: bmp connect HOSTNAME port (1-65535) {min-retry MSEC|max-retry MSEC} [source-interface WORD] + + Add/remove an active outbound BMP session. HOSTNAME is resolved via DNS, + if multiple addresses are returned they are tried in nondeterministic + order. Only one connection will be established even if multiple addresses + are returned. ``min-retry`` and ``max-retry`` specify (in milliseconds) + bounds for exponential backoff. ``source-interface`` is the local interface on + which the connection has to bind. + +.. warning:: + + ``ip access-list`` and ``ipv6 access-list`` are checked for outbound + connections resulting from ``bmp connect`` statements. + +.. clicmd:: bmp listener <X:X::X:X|A.B.C.D> port (1-65535) + + Accept incoming BMP sessions on the specified address and port. You can + use ``0.0.0.0`` and ``::`` to listen on all IPv4/IPv6 addresses. + +.. clicmd:: ip access-list NAME +.. clicmd:: ipv6 access-list NAME + + Restrict BMP sessions to the addresses allowed by the respective access + lists. The access lists are checked for both passive and active BMP + sessions. Changes do not affect currently established sessions. + +BMP data feed configuration +--------------------------- + +The following commands configure what BMP messages are sent on sessions +associated with a particular ``bmp targets``: + +.. clicmd:: bmp stats [interval (100-86400000)] + + Send BMP Statistics (counter) messages at the specified interval (in + milliseconds.) + +.. clicmd:: bmp monitor AFI SAFI <pre-policy|post-policy> + + Perform Route Monitoring for the specified AFI and SAFI. Only IPv4 and + IPv6 are currently valid for AFI. SAFI valid values are currently + unicast, multicast, evpn and vpn. + Other AFI/SAFI combinations may be added in the future. + + All BGP neighbors are included in Route Monitoring. Options to select + a subset of BGP sessions may be added in the future. + +.. clicmd:: bmp mirror + + Perform Route Mirroring for all BGP neighbors. Since this provides a + direct feed of BGP messages, there are no AFI/SAFI options to be + configured. + + All BGP neighbors are included in Route Mirroring. Options to select + a subset of BGP sessions may be added in the future. |