09-17-2010 07:02 AM - edited 03-04-2019 09:48 AM
Hi all,
We have a router with two interfaces connected to the sames ISPs router, running BGP in both interfaces:
Serial0/0/0:0 10.11.8.106 YES NVRAM down down
ATM0/1/0.1 10.11.9.106 YES NVRAM up up
Loopback1 192.168.24.148 YES NVRAM up up
We want to configure all the traffic through Serial 0/0/0 and use ATM0/1/0.1 as backup, for that we have configured the following in BGP:
router bgp 64512
no synchronization
bgp log-neighbor-changes
network 10.11.8.104 mask 255.255.255.252
network 10.11.9.104 mask 255.255.255.252
network 10.11.73.0 mask 255.255.255.0
network 192.168.24.148 mask 255.255.255.255
neighbor 10.11.8.105 remote-as 12338
neighbor 10.11.9.105 remote-as 12338
neighbor 10.11.9.105 route-map OUT in
neighbor 10.11.9.105 route-map Back out
distance bgp 50 50 50
no auto-summary
!
!
route-map BACK permit 10
set as-path prepend 64512 64512
!
route-map OUT permit 10
set local-preference 90
!
For BGP neighbor 10.11.9.105 we try to receive the routes that it announces with local preference 90 and we try to announce our routes with prepend 64512 64512 so always 10.11.8.105 will have the best paths.
Now we are in a situation that neighbour 10.11.8.105 is down.
In our router we are receiving routes OK from 10.11.9.105, but the problem is that we do not see any routes advertised to 10.11.9.105:
sh ip bgp ne 10.11.8.105 routes
Total number of prefixes 0
sh ip bgp ne 10.11.8.105 advertised-routes
Total number of prefixes 0
sh ip bgp ne 10.11.9.105 advertised-routes
Total number of prefixes 0
sh ip bgp ne 10.11.9.105 routes
BGP table version is 1529, local router ID is 192.168.24.148
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
*> 0.0.0.0 10.11.9.105 90 0 12338 12338 ?
*> 10.0.0.0/24 10.11.9.105 90 0 12338 12338 ?
*> 10.3.0.0/24 10.11.9.105 90 0 12338 12338 ?
*> 10.7.254.0/24 10.11.9.105 90 0 12338 12338 ?
*> 10.11.0.0/24 10.11.9.105 90 0 12338 12338 ?
*> 10.11.1.0/24 10.11.9.105 90 0 12338 12338 ?
*> 10.11.1.10/32 10.11.9.105 90 0 12338 12338 ?
*> 10.11.2.0/24 10.11.9.105 90 0 12338 12338 ?
sh ip route | i C
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
C 192.168.24.148 is directly connected, Loopback1
C 10.11.9.104/30 is directly connected, ATM0/1/0.1
Any ideas where the problem could be?
Thank you
Solved! Go to Solution.
09-20-2010 01:18 AM
Hi,
IMHO, the problem could be:
neighbor 10.11.9.105 route-map Back out
distance bgp 50 50 50
no auto-summary
!
route-map BACK permit 10
set as-path prepend 64512 64512
!
As route-map names are case sensitive in IOS, you are referring to a non-existing route-map in your
neighbor 10.11.9.105 route-map Back out
command.
As a result, no prefixes are being advertised to your neighbor.
HTH,
Milan
09-17-2010 07:23 AM
Hello,
the only network that could be sent is :
network 10.11.73.0 mask 255.255.255.0
the other two are:
one is the link with eBGP peer
the other one is the other link that is likely down
the show ip route connected shows that net 10.11.73.0/24 is not a connected route
check with
sh ip route 10.11.73.0
if the route exists in the IP routing table of the node
in other words if you add
router bgp 64512
network 192.168.24.148 mask 255.255.255.255
this route should be sent being alive.
Hope to help
Giuseppe
09-19-2010 09:28 AM
Thank you for your answer Giuslar,
I understand that network 10.11.73.0 is not been anounced because is down and it is not in the routing table, but I do not quite understand why you say networks 192.168.24.148/32 and 10.11.9.104/30 should not be advertised, our intention is to do that:
router bgp 64512
no synchronization
bgp log-neighbor-changes
network 10.11.8.104 mask 255.255.255.252
network 10.11.9.104 mask 255.255.255.252
network 10.11.73.0 mask 255.255.255.0
network 192.168.24.148 mask 255.255.255.255
and both networks are up and as you can see both networks are in the routing table
Serial0/0/0:0 10.11.8.106 YES NVRAM down down
ATM0/1/0.1 10.11.9.106 YES NVRAM up up
Loopback1 192.168.24.148 YES NVRAM up up
sh ip route | i C
Codes: C - connected, S - static, R - RIP, M - mobile, B - BGP
C 192.168.24.148 is directly connected, Loopback1
C 10.11.9.104/30 is directly connected, ATM0/1/0.1
Thank you
09-19-2010 11:14 AM
Hello Lcuchisnamillan,
I beg your pardon I had missed the network command covering the loopback's IP subnet.
About the connected IP subnet, the advertisement should not be seen on receiver side as it is a connected route on it with lower AD but I agree it should be advertised by the node with the network command.
Clearly the other network, that of the loopback should be advertised and received
Have you tried what happens without the applied route-maps?
Hope to help
Giuseppe
09-20-2010 01:18 AM
Hi,
IMHO, the problem could be:
neighbor 10.11.9.105 route-map Back out
distance bgp 50 50 50
no auto-summary
!
route-map BACK permit 10
set as-path prepend 64512 64512
!
As route-map names are case sensitive in IOS, you are referring to a non-existing route-map in your
neighbor 10.11.9.105 route-map Back out
command.
As a result, no prefixes are being advertised to your neighbor.
HTH,
Milan
09-20-2010 02:15 AM
Thank you very much milan,
The problem was there i did not pay attention to the name of the route-map
Thank you again
09-20-2010 02:21 AM
Milan,
Good eye! I was going over it a couple of times and didn't see it... I guess I have to buy a larger monitor
Best regards,
Peter
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