Useful BGP commands on Cisco

(c) https://nets.ucar.edu/nets/devices/routers/bgp/useful-bgp-commands.shtml

When BGP is not behaving correctly, a “trick” to temporarily stop peering with a neighbor is to use the following command:

router bgp 194
neighbor
password xxx

Since the other router doesn’t have the same password, the two routers will stop talking to one another, without you having to do anything else. Later, when the problem is resolved, simply remove the line to reestablish peerage.

To see what routes you’re getting from an AS, use the command

show ip bgp regexp

To see what routes you’re getting from a neighbor, do

show ip bgp vpnv4 vrf tr neighbors 192.43.217.133 received-routes
show ip bgp vpnv4 vrf nlr neighbors 192.43.217.138 received-routes
show ip bgp vpnv4 vrf nlr neighbors 216.24.184.25 received-routes

To see a quick status of all BGP, on a !non-vrf router and a vrf router,

show ip bgp summary
show ip bgp vpnv4 vrf tr summary

To see BGP routes, in the default table or an explicit VRF,

show ip bgp
show ip bgp vpnv4 vrf tr

To see what routes you’re getting from a neighbor, use one of these

show ip bgp neighbor routes
show ip bgp vpnv4 vrf tr neighbor 192.43.217.133

To see what routes you’re sending to a neighbor, use the command

show ip bgp neighbor advertised-routes

To clear a BGP session:

clear ip bgp

To find out who owns, say, Autonomous System number 44, go to http://www.arin.net/ and type AS44. Or get file ftp://rs.arin.net/netinfo/asn.txt. Or Web to http://www.arin.net/docs.html.

To see what’s happening with BGP, use the commands

terminal monitor
debug ip bgp events

To show all the networks sourced by this AS

show ip bgp regexp

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