Useful BGP commands on Cisco Routers
- When BGP is not behaving correctly, a “trick” to temporarily stop peering with a neighbor is to use the following command:
router bgp 194<ipaddress>
neighborpassword xxxSince 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 <regluar-expression-for-an-AS> - 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 <IP-address-of-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 <IP-address-of-neighbor> advertised-routes - To clear a BGP session:
clear ip bgp <ip-address of neighbor> - To find out who owns, say, Autonomous System number 44, go to
http://www.arin.net/and typeAS44. Or get fileftp://rs.arin.net/netinfo/asn.txt. Or Web tohttp://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 ^$