R1 [AS10] ----- R2 [AS256]------R6[AS256]
The network between R2 and R6 is 150.100.100.0/24. This network is advertised into BGP on R6 but not R2. Because this is a connected route, R2 does not install it as a BGP route. It does receive the advertisement however and propagate it to R1.
Here is the R2 config:
R2#show run | sec router bgp
router bgp 256
no synchronization
bgp log-neighbor-changes
network 150.100.25.0 mask 255.255.255.0
neighbor 150.100.12.1 remote-as 10
neighbor 150.100.100.6 remote-as 256
neighbor 150.100.100.6 route-reflector-client
no auto-summary
Here is the R6 config:
R6#show run | sec router bgp
router bgp 256
no synchronization
bgp log-neighbor-changes
network 150.100.69.0 mask 255.255.255.0
network 150.100.96.0 mask 255.255.255.0
network 150.100.100.0 mask 255.255.255.0
neighbor 150.100.100.2 remote-as 256
no auto-summary
Here is R2's BGP table:
R2#show ip bgp | beg Network
Network Next Hop Metric LocPrf Weight Path
*> 150.100.25.0/24 0.0.0.0 0 32768 i
*>i150.100.69.0/24 150.100.100.6 0 100 0 i
*>i150.100.96.0/24 150.100.100.6 0 100 0 i
r>i150.100.100.0/24 150.100.100.6 0 100 0 i
Notice the last entry has an 'r' next to it. This is not installed in the route table as a BGP route. It is already installed as connected. This is known as a RIB failure.
But the route is advertised to R1:
R1#show ip route bgp
150.100.0.0/16 is variably subnetted, 7 subnets, 2 masks
B 150.100.96.0/24 [20/0] via 150.100.12.2, 00:05:25
B 150.100.100.0/24 [20/0] via 150.100.12.2, 00:05:25
B 150.100.69.0/24 [20/0] via 150.100.12.2, 00:05:25
B 150.100.25.0/24 [20/0] via 150.100.12.2, 00:05:25
Now here's the tricky part. You can use the BGP suppress-inactive command to prevent RIB failures from getting advertised. But when I use it on R2 and R6 it doesn't work quite like I expected.
R2#show run | inc inac
bgp suppress-inactive
R2#
R6#show run | inc inac
bgp suppress-inactive
R6#
Notice here that R1 still has the 150.100.100.0 route from R2:
R1#clear ip bgp *
R1#
*Nov 23 13:59:37.379: %BGP-5-ADJCHANGE: neighbor 150.100.12.2 Down User reset
*Nov 23 13:59:38.039: %BGP-5-ADJCHANGE: neighbor 150.100.12.2 Up
R1#
R1#show ip bgp
BGP table version is 5, local router ID is 200.0.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.100.25.0/24 150.100.12.2 0 0 256 i
*> 150.100.69.0/24 150.100.12.2 0 256 i
*> 150.100.96.0/24 150.100.12.2 0 256 i
*> 150.100.100.0/24 150.100.12.2 0 256 i
Anybody know how this command is supposed to work in preventing RIB failures from getting advertised in BGP?
The network between R2 and R6 is 150.100.100.0/24. This network is advertised into BGP on R6 but not R2. Because this is a connected route, R2 does not install it as a BGP route. It does receive the advertisement however and propagate it to R1.
Here is the R2 config:
R2#show run | sec router bgp
router bgp 256
no synchronization
bgp log-neighbor-changes
network 150.100.25.0 mask 255.255.255.0
neighbor 150.100.12.1 remote-as 10
neighbor 150.100.100.6 remote-as 256
neighbor 150.100.100.6 route-reflector-client
no auto-summary
Here is the R6 config:
R6#show run | sec router bgp
router bgp 256
no synchronization
bgp log-neighbor-changes
network 150.100.69.0 mask 255.255.255.0
network 150.100.96.0 mask 255.255.255.0
network 150.100.100.0 mask 255.255.255.0
neighbor 150.100.100.2 remote-as 256
no auto-summary
Here is R2's BGP table:
R2#show ip bgp | beg Network
Network Next Hop Metric LocPrf Weight Path
*> 150.100.25.0/24 0.0.0.0 0 32768 i
*>i150.100.69.0/24 150.100.100.6 0 100 0 i
*>i150.100.96.0/24 150.100.100.6 0 100 0 i
r>i150.100.100.0/24 150.100.100.6 0 100 0 i
Notice the last entry has an 'r' next to it. This is not installed in the route table as a BGP route. It is already installed as connected. This is known as a RIB failure.
But the route is advertised to R1:
R1#show ip route bgp
150.100.0.0/16 is variably subnetted, 7 subnets, 2 masks
B 150.100.96.0/24 [20/0] via 150.100.12.2, 00:05:25
B 150.100.100.0/24 [20/0] via 150.100.12.2, 00:05:25
B 150.100.69.0/24 [20/0] via 150.100.12.2, 00:05:25
B 150.100.25.0/24 [20/0] via 150.100.12.2, 00:05:25
Now here's the tricky part. You can use the BGP suppress-inactive command to prevent RIB failures from getting advertised. But when I use it on R2 and R6 it doesn't work quite like I expected.
R2#show run | inc inac
bgp suppress-inactive
R2#
R6#show run | inc inac
bgp suppress-inactive
R6#
Notice here that R1 still has the 150.100.100.0 route from R2:
R1#clear ip bgp *
R1#
*Nov 23 13:59:37.379: %BGP-5-ADJCHANGE: neighbor 150.100.12.2 Down User reset
*Nov 23 13:59:38.039: %BGP-5-ADJCHANGE: neighbor 150.100.12.2 Up
R1#
R1#show ip bgp
BGP table version is 5, local router ID is 200.0.3.1
Status codes: s suppressed, d damped, h history, * valid, > best, i - internal,
r RIB-failure, S Stale
Origin codes: i - IGP, e - EGP, ? - incomplete
Network Next Hop Metric LocPrf Weight Path
*> 150.100.25.0/24 150.100.12.2 0 0 256 i
*> 150.100.69.0/24 150.100.12.2 0 256 i
*> 150.100.96.0/24 150.100.12.2 0 256 i
*> 150.100.100.0/24 150.100.12.2 0 256 i
Anybody know how this command is supposed to work in preventing RIB failures from getting advertised in BGP?
