Adjusting and Optimizing IPv6 BGP Networks 1025After establishing an IPv6 BGP connection, two routers send keepalive messagesperiodically to each other to keep the connection. If a router receives no keepalivemessage from the peer after the holdtime elapses, it tears down the connection.When establishing an IPv6 BGP connection, the two parties compare theirholdtime values, taking the shorter one as the common holdtime. If the holdtimeis 0, neither keepalive massage is sent, nor holdtime is checked.■ IPv6 BGP connection soft resetAfter modifying a route selection policy, you have to reset IPv6 BGP connections tomake the new one take effect, causing a short time disconnection. The currentIPv6 BGP implementation supports the route-refresh feature that enables dynamicIPv6 BGP routing table refresh without needing to disconnect IPv6 BGP links.With this feature enabled on all IPv6 BGP routers in a network, when a routingpolicy modified on a router, the router advertises a route-refresh message to itspeers, which then send their routing information back to the router. Therefore, thelocal router can perform dynamic routing information update and apply the newpolicy without tearing down connections.If a router not supporting route-refresh exists in the network, you need toconfigure the peer keep-all-routes command on the router to save all routeupdates, and then use the refresh bgp ipv6 command to soft-reset IPv6 BGPconnections.Prerequisites Before configuring IPv6 BGP timers, you have:■ Enabled IPv6 function■ Configured IPv6 BGP basic functionsConfiguring IPv6 BGPTimersFollow these steps to configure IPv6 BGP timers:To do... Use the command... RemarksEnter system view system-view -Enter BGP view bgp as-number RequiredEnter IPv6 address family view ipv6-family -Configure IPv6BGP timersSpecifykeepaliveinterval andholdtimetimer keepalive keepalivehold holdtimeOptionalThe keepalive intervaldefaults to 60 seconds,holdtime defaults to 180seconds.Configurekeepaliveinterval andholdtime for apeer/peer grouppeer { ipv6-group-name |ipv6-address } timerkeepalive keepalive holdholdtimeConfigure the interval forsending the same update to apeer/peer grouppeer { ipv6-group-name |ipv6-address }route-update-intervalsecondsOptionalThe interval for sending thesame update to an IBGP peeror an EBGP peer defaults to15 seconds or 30 seconds
