388Tuning and optimizing IPv6 BGP networksThis section describes configurations of IPv6 BGP timers, IPv6 BGP connection soft reset, and themaximum number of load balanced routes.• IPv6 BGP timersAfter establishing an IPv6 BGP connection, two routers send keepalive messagesperiodically to each other to keep the connection. If a router receives no keepalive messagefrom the peer after the holdtime elapses, it tears down the connection.When establishing an IPv6 BGP connection, the two parties compare their holdtimes, takingthe shorter one as the common holdtime. If the holdtime is 0, neither keepalive message issent, nor holdtime is checked.• IPv6 BGP connection soft resetAfter modifying a route selection policy, you must reset IPv6 BGP connections to make thenew one take effect. The current IPv6 BGP implementation supports the route-refresh featurethat enables dynamic route-refresh without needing to disconnect IPv6 BGP links.After this feature is enabled on all IPv6 BGP routers, a router that wants to apply a newroute selection policy advertises a route-refresh message to its peers, which then send theirrouting information to the router. After receiving the routing information, the router canperform dynamic route update by using the new policy without tearing down connections.If a peer not supporting route-refresh exists in the network, you must configure the peer keep-all-routes command to save all routes from the peer, which are used during applying the newroute selection policy.Prerequisites• Enable IPv6• Configure IPv6 BGP basic functionsConfiguring IPv6 BGP timersTo do… Use the command… RemarksStep 1 Enter system view system-view —Step 2 Enter BGP view bgp as-number RequiredStep 3 Enter IPv6 address family view ipv6-family —Step 4 ConfigureIPv6 BGPtimersSpecify keepaliveinterval andholdtimetimer keepalive keepalive holdholdtime OptionalThe keepalive intervaldefaults to 60 seconds,holdtime defaults to180 seconds.Configurekeepalive intervaland holdtime foran IPv6peer/peer grouppeer { ipv6-group-name | ipv6-address } timer keepalivekeepalive hold holdtime
