Cisco R&S: Frequent commands used when configuring BGP

#router bgp 100 -  only one BGP process per router

#network x.x.x.x mask x.x.x.x - using this command will not automatically form a neighbor relationship

#neighbor x.x.x.x remote-as x.x.x.x - peer router

#timers bgp x x - change the keepalive and holdtime timers respectively

#neighbor x.x.x.x update-source Loopback 0 - Instruct the router to use an operational interface for TCP connections with the neighbor. Preferably a loopback interface

#neighbor x.x.x.x ebgp multihop x - only for ebgp routers that are not directly connected to establish a session. x is the number of hops to the neighbor.

#neighbor x.x.x.x soft-reconfiguration inbound - router stores all updates  from the neighbour incase the inbound policy is changed. Memory intensive

#synchronization - router can now announce routes learnt via iBGP even if these routes are unknown via IGP

#neighbor x.x.x.x default-originate - default route will only be sent to the specified neighbor

network - advertises a default route to all peers

maximum-paths 3 - load balancing over 3 equal paths

maximum-paths ibgp 3

maximum-paths ebgp 3

neighbor x.x.x.x password xxxx - router and peer will use md5 authentication  for TCP connection between them. Must be same on both.

neighbor x.x.x.x next-hop-self - this router will be used as the next hop to advertise all updates to the indicated neighbour.

neighbor x.x.x.x next-hop-unchanged - nexthop is unchanged

neighbor x.x.x.x remove-private-as - only for ebgp neighbours. it removes private AS numbers before propagating to the Internet.

neighbor x.x.x.x weight xxx - set the weight of all updates from the neighbour to xxx. Not propagaetd to other routers.

bgp default local-preference 150  - set the default local preference.

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