Loop backs as BGP Neighbors

adriansizemore

I was having some issues bringing up bgp neighbors on my two CE routers. I looked at the RD info on the PE's, and they were receiving bgp updates for the CE routers. However, I was not able to get the LBs on my CE routers to become BGP neighbors.

I had to redistrubute connected and configure a BGP neighbor. Is this the right way to do it, or is there a better, more appropriate way?

Configs:

CE (CU1)
router bgp 65101
bgp log-neighbor-changes
neighbor 12.0.0.3 remote-as 65102
neighbor 12.0.0.3 ebgp-multihop 254
neighbor 12.0.0.3 update-source Loopback0
neighbor 172.16.1.2 remote-as 65400
!
address-family ipv4
redistribute connected
redistribute static
neighbor 12.0.0.3 activate
neighbor 172.16.1.2 activate
no auto-summary
no synchronization
network 12.0.0.1
exit-address-family
!
ip route 0.0.0.0 0.0.0.0 172.16.1.2
!

cu1#show ip route
Gateway of last resort is 172.16.1.2 to network 0.0.0.0
172.16.0.0/30 is subnetted, 2 subnet
B 172.16.1.4 [20/0] via 172.16.1.2, 00:11:49
C 172.16.1.0 is directly connected, FastEthernet0/0
12.0.0.0/32 is subnetted, 2 subnets
C 12.0.0.1 is directly connected, Loopback0
B 12.0.0.3 [20/0] via 12.0.0.3, 00:00:00
S* 0.0.0.0/0 [1/0] via 172.16.1.2
cu1#
cu1#sho ip bgp
BGP table version is 50, local router ID is 12.0.0.1
Network Next Hop Metric LocPrf Weight Path
*> 12.0.0.1/32 0.0.0.0 0 32768 ?
*> 12.0.0.3/32 12.0.0.3 0 0 65102 ?
* 172.16.1.2 0 65400 65102 ?
* 172.16.1.0/30 12.0.0.3 0 65102 65400 ?
*> 0.0.0.0 0 32768 ?
* 172.16.1.2 0 0 65400 ?
* 172.16.1.4/30 12.0.0.3 0 0 65102 ?
*> 172.16.1.2 0 65400 ?


CE (CU1A)
router bgp 65102
bgp log-neighbor-changes
neighbor 12.0.0.1 remote-as 65101
neighbor 12.0.0.1 ebgp-multihop 254
neighbor 12.0.0.1 update-source Loopback0
neighbor 172.16.1.6 remote-as 65400
!
address-family ipv4
redistribute connected
redistribute static
neighbor 12.0.0.1 activate
neighbor 172.16.1.6 activate
no auto-summary
no synchronization
network 12.0.0.3
exit-address-family
!
ip route 0.0.0.0 0.0.0.0 172.16.1.6

cu1a#show ip route
Gateway of last resort is 172.16.1.6 to network 0.0.0.0
172.16.0.0/30 is subnetted, 2 subnets
C 172.16.1.4 is directly connected, FastEthernet0/1
B 172.16.1.0 [20/0] via 172.16.1.6, 00:43:24
12.0.0.0/32 is subnetted, 2 subnets
B 12.0.0.1 [20/0] via 12.0.0.1, 00:00:00
C 12.0.0.3 is directly connected, Loopback0
S* 0.0.0.0/0 [1/0] via 172.16.1.6

cu1a#sh ip bgp
BGP table version is 95, local router ID is 12.0.0.3
Network Next Hop Metric LocPrf Weight Path
*> 12.0.0.1/32 12.0.0.1 0 0 65101 ?
* 172.16.1.6 0 65400 65101 ?
*> 12.0.0.3/32 0.0.0.0 0 32768 ?
* 172.16.1.0/30 12.0.0.1 0 0 65101 ?
*> 172.16.1.6 0 65400 ?
* 172.16.1.4/30 12.0.0.1 0 65101 65400 ?
*> 0.0.0.0 0 32768 ?
* 172.16.1.6 0 0 65400 ?
cu1a#

rossonieri#1

hi adrian,

you mean you cant make them peers between 2 routers CE-PE?
have you created a static route on both pointing their loopback?

ps :

redistribute connected has a slight effect being redistributing all unnecessary route that CE shouldnt know about, so better to distribute it carefully - especially when you are also redistributing IGP to BGP.

and that is very huge lab you have there,
how many machines involved? how much RAM?

APA

IGP which contains only the infrastructure addresses used to form BGP peerings...

or

Why didn't you just use network statements? If they are connected networks just use network x.x.x.x mask x.x.x.x then your CE's would advertise that to your PE's\remote PE's thus propagating NLRI to the remote CE.

networker050184

APA wrote: »

IGP which contains only the infrastructure addresses used to form BGP peerings...

This is the best option IMO. If you are going to redistribute connected make sure you filter appropriately.

Also keep in mind BGP will not use a default route to form the peer. You must have a more specific route in the routing table.

APA

networker050184 wrote: »

This is the best option IMO. If you are going to redistribute connected make sure you filter appropriately.

Also keep in mind BGP will not use a default route to form the peer. You must have a more specific route in the routing table.

Couldn't agree with you more!