02-21-2007 04:54 PM - edited 03-05-2019 02:30 PM
I have 2 routers connected, can ping each other on the F0/0 interfaces. Each has loopback interfaces which are the only once advertised in BGP (AS1).
Problem: I am not able to ping the loopback addresses.
Any ideas. This should be possible.
Config:
router bgp 1
synchronization
bgp log-neighbor-changes
network 1.0.0.0
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 update-source Loopback0
no auto-summary
R2#sh run | beg bgp
router bgp 1
synchronization
bgp log-neighbor-changes
network 2.0.0.0
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 update-source Loopback0
no auto-summary
The routers can ping each other:
R2#ping 192.1.12.1
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 192.1.12.1, timeout is 2 seconds:
!!!!!
Success rate is 100 percent (5/5), round-trip min/avg/max = 96/140/220 ms
What did I miss?
Debug message from R1:
*Mar 1 06:59:01.918: BGP: 2.2.2.2 active open failed - no route to peer, open a ctive delayed 29293ms (35000ms max, 28% jitter)
Solved! Go to Solution.
02-21-2007 05:58 PM
Jacob,
What Mike was asking you to do is to establish BGP peering one of two-ways.
1. If you want to use loopback addresses to peer then you need to have a static or another IGP route (not BGP) to the far end loopback address. You would also need to reinstate the 'update-source' command that you removed. You need a config similar to this one;
R1:
ip route 1.1.1.1 255.255.255.255 192.1.12.1
R2:
ip route 2.2.2.2 255.255.255.255 (next_hop_ip)
2. Your second option is to reconfigure, on both routers, the "neighbor (physical_int_IP_address) remote-as 7000' to the physical interface IP on the far end device. This doesn't need any static/IGP routing as the peering IP addresses are directly connected.
HTH
Sundar
02-21-2007 05:01 PM
you can either add a static route to your loopbacks or change the update-cource loopback 0 to 'next hop self"
i.e.
neighbor 1.1.1.1 next hop self
02-21-2007 05:04 PM
Are the loopback interfaces in the Ip Routing table of the applicable routers?
AFAIK
Sychronization will not allow the loopback0: to be advertised in BGP unless there is a route know by the igp?
Show a show ip route.
02-21-2007 05:07 PM
The adjacency between R1 & R2 does not come up because:
1) update-source Loopback0 tells BGP to establish a connection to/from it's Loopback0
2) BGP doesn't know how to reach the remote Loopback0
*Mar 1 06:59:01.918: BGP: 2.2.2.2 active open failed -
no route to peer, <=== this is the key message
open a ctive delayed 29293ms (35000ms max, 28% jitter)
There are two ways to correct this:
1) Best Practice - You'll need to configure either a static route or an IGP (RIP, OSPF, EIGRP, etc) to exchange the routes from Loopback to Loopback so that BGP can establish that connection.
2) Remove the update-source loopback0 clause from both routers' config. The connection will then be established from the directly connected interfaces. While this approach will fix your back-to-back router issue, it is generally not a recommended approach for real networks because of the potential for broken next-hop information and reliance on the directly connected interface for peering.
HTH,
Mike
02-21-2007 05:08 PM
Looks like I didn't type quickly enough - I'm late to the party... :-)
02-21-2007 05:30 PM
Thanks Guys
What I would like to achieve is the second option given by "mikedavi1"
I have removed "update-source loopback 0"
But I still cannot ping both ends via the loopback interfaces.
R2#sh run | begin bgp
router bgp 1
synchronization
bgp log-neighbor-changes
network 2.0.0.0
neighbor 1.1.1.1 remote-as 1
neighbor 1.1.1.1 next-hop-self
no auto-summary
R2#sh ip route | begin Gateway
Gateway of last resort is not set
C 192.1.12.0/24 is directly connected, FastEthernet0/1
C 2.0.0.0/8 is directly connected, Loopback0
C 192.1.25.0/24 is directly connected, Serial1/0.25
R1#sh run | begin bgp
router bgp 1
synchronization
bgp log-neighbor-changes
network 1.0.0.0
neighbor 2.2.2.2 remote-as 1
neighbor 2.2.2.2 next-hop-self
no auto-summary
R1#sh ip route | begin Gateway
Gateway of last resort is not set
C 192.1.12.0/24 is directly connected, FastEthernet0/1
C 1.0.0.0/8 is directly connected, Loopback0
R1#ping 2.2.2.2
Type escape sequence to abort.
Sending 5, 100-byte ICMP Echos to 2.2.2.2, timeout is 2 seconds:
.....
Any more ideas?
02-21-2007 05:58 PM
Jacob,
What Mike was asking you to do is to establish BGP peering one of two-ways.
1. If you want to use loopback addresses to peer then you need to have a static or another IGP route (not BGP) to the far end loopback address. You would also need to reinstate the 'update-source' command that you removed. You need a config similar to this one;
R1:
ip route 1.1.1.1 255.255.255.255 192.1.12.1
R2:
ip route 2.2.2.2 255.255.255.255 (next_hop_ip)
2. Your second option is to reconfigure, on both routers, the "neighbor (physical_int_IP_address) remote-as 7000' to the physical interface IP on the far end device. This doesn't need any static/IGP routing as the peering IP addresses are directly connected.
HTH
Sundar
02-21-2007 07:12 PM
Thanks, Sundar. I wasn't too clear about the fix.
02-21-2007 08:17 PM
Thanks everyone, I am well sorted out with this one now.
Regards
02-21-2007 11:53 PM
1.First of all for IBGP to work ur synchronisation must be disabled.
no synchronisation.
2. To work IBGP with loopback ip u have to route the loopback ip pointing towards other router.
R1:
ip route 1.1.1.1 255.255.255.255 192.1.12.1
R2:
ip route 2.2.2.2 255.255.255.255 (next_hop_ip)
Rate this if it works.
Thanks.
Yash
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