Working on the simulation to show how BGP network x.x.x.x backdoor is working. So in the below example i have router which is configured with backdoor, when IGP (OSPF) is running i see this route in routing table, but from curiosity i shut that link to see if my route (172.16.3.0) will show up in bgp table. It is not showing up? My understanding of the backdoor is that it will be advertised to eBGP peers once IGP link go down, also this is local subnet to this router so i imagined that would be advertised right away?
R7#sh run | s bgp router bgp 3 bgp router-id 192.168.3.254 bgp log-neighbor-changes network 172.16.1.0 mask 255.255.255.0 network 172.16.3.0 mask 255.255.255.0 backdoor network 172.17.0.0 network 192.168.6.128 mask 255.255.255.128 neighbor 10.255.255.3 remote-as 1 neighbor 10.255.255.3 ebgp-multihop 2 neighbor 10.255.255.3 update-source Loopback0 neighbor 10.255.255.3 filter-list 1 out neighbor 192.168.100.38 remote-as 4 neighbor 192.168.100.38 filter-list 1 out neighbor 192.168.100.42 remote-as 5 neighbor 192.168.100.42 filter-list 1 out R7#sh ip bgp nei 10.255.255.3 adver R7#sh ip bgp nei 10.255.255.3 advertised-routes BGP table version is 13, local router ID is 192.168.3.254 Status codes: s suppressed, d damped, h history, * valid, > best, i - internal, r RIB-failure, S Stale, m multipath, b backup-path, f RT-Filter, x best-external, a additional-path, c RIB-compressed, Origin codes: i - IGP, e - EGP, ? - incomplete RPKI validation codes: V valid, I invalid, N Not found
Network Next Hop Metric LocPrf Weight Path *> 172.16.1.0/24 0.0.0.0 0 32768 i *> 172.17.0.0 0.0.0.0 0 32768 i *> 192.168.6.128/25 0.0.0.0 0 32768 i
Total number of prefixes 3 R7#
R7#sh ip int br | e una Interface IP-Address OK? Method Status Protocol Ethernet0/0 192.168.100.37 YES manual up up Serial2/0 192.168.100.26 YES manual up up Serial2/1 192.168.100.41 YES manual up up Loopback0 10.255.255.7 YES manual up up Loopback1 172.16.1.1 YES manual up up Loopback3 172.16.3.1 YES manual up up Loopback10 192.168.6.129 YES manual up up Loopback11 172.17.0.1 YES manual up up