ZAPI message for detecting/monitoring BGP peer status and BFD status

[sakthishanmugam02]

hi Team,

I am looking for message which would help in monitoring the status of BGP and BFD client status. If it becomes DOWN/UP - the Zebra client has to take some actions based on that. Is there any message for that?

[rzalamena]

The message header type is ZEBRA_INTERFACE_BFD_DEST_UPDATE which is handled in lib/bfd.c by zclient_bfd_session_update.

The parser for the zebra BFD message is here: https://github.com/FRRouting/frr/blob/master/lib/bfd.c#L141

The message format is as the following:

	/*
	 * Message format:
	 * - header: command, vrf
	 * - l: interface index
	 * - c: family
	 *   - AF_INET:
	 *     - 4 bytes: ipv4
	 *   - AF_INET6:
	 *     - 16 bytes: ipv6
	 *   - c: prefix length
	 * - l: bfd status
	 * - c: family
	 *   - AF_INET:
	 *     - 4 bytes: ipv4
	 *   - AF_INET6:
	 *     - 16 bytes: ipv6
	 *   - c: prefix length
	 * - c: cbit
	 *
	 * Commands: ZEBRA_BFD_DEST_REPLAY
	 *
	 * q(64), l(32), w(16), c(8)
	 */

(code for encoder here: https://github.com/FRRouting/frr/blob/master/bfdd/ptm_adapter.c#L180 )

In the BGP case, for an example, the code path should be as following:

• Message is received by bgpd daemon
  • zclient_bfd_session_update calls all registered sessions ( https://github.com/FRRouting/frr/blob/master/lib/bfd.c#L903 )
  • bfd_session_status_update BGP's BFD callback ( https://github.com/FRRouting/frr/blob/master/bgpd/bgp_bfd.c#L34 )

The zebra specific code is here: https://github.com/FRRouting/frr/blob/master/zebra/zebra_ptm.c#L1455 , however zebra acts only as a proxy between bfdd and the consumer daemons (e.g. bgpd). Currently zebra doesn't do anything with the BFD messages.

[sakthishanmugam02]

@rzalamena thank you! what about BGP session status alone, when there is no BFD configured, what is the equivalent message in ZAPI for BGP peer status?

[rzalamena]

I don't recall any BGP messages about peer status, this information is probably not being shared between daemons. Maybe someone with more BGP knowledge might get you a better answer.

[ton31337]

Only about the interface status, not the peer status. Such specific messages between daemons are not implemented right now. What is the use case you are trying to accomplish?

[sakthishanmugam02]

we have a control plane where centralised route table are managed for our network. so one of our control plane software establishes the ZAPI connection with the FRR. whenever there is change in route, we want to update our route tables.
whenever the peer goes down, we are not receiving any DELETE messages for the routes + we also want to monitor the live status of each peer connected.

[donaldsharp]

I'm not convinced that a zapi interaction is what you really want. Look at the lua integration for zebra for routes added imo. Additionally it could be easily extended for peer up/down events for bgp (or other daemons, It might have already been done for bgp I do not remember).

As a note -> There is never going to be zapi level integration for daemon private information( ala bgp peer up/down events as an example )