Operation Manual – Routing ProtocolH3C S7500 Series Ethernet Switches Chapter 6 BGP Configuration6-19To do... Use thecommand... RemarksConfigure the number of routesused for BGP load balance balance numOptionalBy default, the systemdoes not adopt BGP loadbalance.Caution:z A reasonable maximum interval for sending Keepalive message is one third of theHoldtime, and the interval cannot be less than 1 second, therefore, if the Holdtimeis not 0, it must be at least three seconds.z BGP soft reset can refresh the BGP routing table and apply a new routing policywithout breaking the BGP connections.z BGP soft reset requires that all the BGP routers in a network support theroute-refresh function. If there is any router not supporting the route-refreshfunction, you need to configure the peer keep-all-routes command to save all theinitial routing information of peers for the use of BGP soft reset.6.7 Configuring a Large-Scale BGP NetworkIn a large-scale network, there are large quantities of peers. Configuring andmaintaining the peer becomes a big problem. Using peer group can ease themanagement and improve the routes sending efficiency. According to the differentASs where peers reside, the peer groups fall into IBGP peer groups and EBGP peergroups. For the EBGP peer group, it can be further divided into pure EBGP peer groupand hybrid EBGP peer group according to whether the peers in the EBGP groupbelong to the same exterior AS or not.Community can also be used to ease the routing policy management. And itsmanagement range is much wider than that of the peer group. It controls the routingpolicy of multiple BGP routers.In an AS, to ensure the connectivity among IBGP peers, you need to set up afully-meshed connection among them. When there are too many IBGP peers, it willcost a lot in establishing a fully-meshed network. Using RR or confederation can solvethe problem. In a large AS, RR and confederation can be used simultaneously.6.7.1 Configuration PrerequisitesBefore configuring a large-scale BGP network, you need to ensure:Network layer connectivity between adjacent nodes.
