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diff --git a/docs/sources/graceful-restart.md b/docs/sources/graceful-restart.md new file mode 100644 index 00000000..3d83ee76 --- /dev/null +++ b/docs/sources/graceful-restart.md @@ -0,0 +1,141 @@ +# Graceful Restart + +This page explains how to configure [Graceful Restart](https://tools.ietf.org/html/rfc4724). +Graceful Restart has two sides. One is restarting speaker which does restart, +the other is receiving speaker (helper speaker) which helps a restarting speaker +to do graceful restart. GoBGP supports both roles. + +## Contents + +- [Helper speaker](#helper) +- [Restarting speaker](#restarting) + +## <a name="helper"> Helper speaker + +Below is the configuration to enable helper speaker behavior. + +```toml +[global.config] + as = 64512 + router-id = "192.168.255.1" + +[[neighbors]] + [neighbors.config] + neighbor-address = "10.0.255.1" + peer-as = 65001 + [neighbors.graceful-restart.config] + enabled = true +``` + +Check graceful restart capability is negotiated. + +```shell +$ gobgp n 10.0.255.1 +BGP neighbor is 10.0.255.1, remote AS 65001 + BGP version 4, remote router ID 192.168.0.2 + BGP state = BGP_FSM_ESTABLISHED, up for 00:00:36 + BGP OutQ = 0, Flops = 0 + Hold time is 0, keepalive interval is 30 seconds + Configured hold time is 90, keepalive interval is 30 seconds + Neighbor capabilities: + BGP_CAP_MULTIPROTOCOL: + RF_IPv4_UC: advertised and received + BGP_CAP_ROUTE_REFRESH: advertised and received + BGP_CAP_GRACEFUL_RESTART: advertised and received + Remote: restart time 90 sec + RF_IPv4_UC + BGP_CAP_FOUR_OCTET_AS_NUMBER: advertised and received + Message statistics: + Sent Rcvd + Opens: 1 1 + Notifications: 0 0 + Updates: 2 1 + Keepalives: 2 2 + Route Refesh: 0 0 + Discarded: 0 0 + Total: 5 4 + Route statistics: + Advertised: 1 + Received: 0 + Accepted: 0 +``` + +## <a name="restarting"> Restarting speaker + +To support restarting speaker behavior, try the configuration below. + +```toml +[global.config] + as = 64512 + router-id = "192.168.255.1" + +[[neighbors]] + [neighbors.config] + neighbor-address = "10.0.255.1" + peer-as = 65001 + [neighbors.graceful-restart.config] + enabled = true + restart-time = 120 + [[neighbors.afi-safis]] + afi-safi-name = "ipv4-unicast" + [neighbors.afi-safis.mp-graceful-restart.config] + enabled = true +``` + +By this configuration, if graceful restart capability is negotiated with the peer, +the peer starts graceful restart helper procedure, when `gobgpd` dies involuntarily or +`SIGINT`, `SIGKILL` signal is sent to `gobgpd`. +Note when `SIGTERM` signal is sent to `gobgpd`, graceful restart negotiated peers +don't start graceful restart helper procedure, since `gobgpd` sends notification +messages to these peers before it die. + +When you restart `gobgpd`, add `-r` option to let peers know `gobgpd` is +recovered from graceful restart. + +```shell +$ gobgpd -f gobgpd.conf -r +``` + +Let's see how capability negotiation changes. + +```shell +$ gobgp n 10.0.255.1 +BGP neighbor is 10.0.255.1, remote AS 65001 + BGP version 4, remote router ID 192.168.0.2 + BGP state = BGP_FSM_ESTABLISHED, up for 00:00:03 + BGP OutQ = 0, Flops = 0 + Hold time is 0, keepalive interval is 30 seconds + Configured hold time is 90, keepalive interval is 30 seconds + Neighbor capabilities: + BGP_CAP_MULTIPROTOCOL: + RF_IPv4_UC: advertised and received + BGP_CAP_ROUTE_REFRESH: advertised and received + BGP_CAP_GRACEFUL_RESTART: advertised and received + Local: restart time 90 sec, restart flag set + RF_IPv4_UC, forward flag set + Remote: restart time 90 sec + RF_IPv4_UC + BGP_CAP_FOUR_OCTET_AS_NUMBER: advertised and received + Message statistics: + Sent Rcvd + Opens: 1 1 + Notifications: 0 0 + Updates: 2 1 + Keepalives: 1 1 + Route Refesh: 0 0 + Discarded: 0 0 + Total: 4 3 + Route statistics: + Advertised: 1 + Received: 0 + Accepted: 0 +``` + +You can see `restart flag` and `forward flag` is set. + +Without `-r` option, the peers which are under helper procedure will +immediately withdraw all routes which were advertised from `gobgpd`. + +Also, when `gobgpd` doesn't recovered within `restart-time`, the peers will +withdraw all routes. +Default value of `restart-time` is equal to `hold-time`. |