05-24-2018 02:45 AM - edited 03-08-2019 03:07 PM
Hi all,
I am building a basic eBGP lab to test out the concept of making 2 non-directly connected neighbours BGP peers.
The network the BGP routers will be going 'across' is an OSPF network.
The lab is below along with relevant configuration:
OSPF Config:
R4 router ospf 10 network 172.16.0.0 0.0.0.3 area 0 network 172.16.0.8 0.0.0.3 area 0 R5 router ospf 10 network 172.16.0.4 0.0.0.3 area 0 network 172.16.0.8 0.0.0.3 area 0
Unfortunately it doesn't seem to work, does anyone have some idea what I am doing wrong?
05-24-2018 02:55 AM
So are you trying to peer across the 172.16.x.x OSPF network ?
What do the routing tables on R4 and R5 look like ie. do they have routes to each others IPs ?
Also R4's neighbor IP cannot be 10.0.0.4 as that is a subnet address in your topology.
Jon
05-24-2018 03:05 AM
Hi Jon,
Thanks for pointing that out, not sure how I missed that. I changed the neighbor to 10.0.0.5 instead.
As requested, the Routing Tables of R4 and R5 are below:
R4 Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.0.0.0/30 is directly connected, Ethernet0/0 L 10.0.0.2/32 is directly connected, Ethernet0/0 172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks C 172.16.0.0/30 is directly connected, Ethernet0/1 L 172.16.0.1/32 is directly connected, Ethernet0/1 O 172.16.0.4/30 [110/20] via 172.16.0.10, 00:02:31, Ethernet0/2 [110/20] via 172.16.0.2, 00:02:31, Ethernet0/1 C 172.16.0.8/30 is directly connected, Ethernet0/2 L 172.16.0.9/32 is directly connected, Ethernet0/2 R5 Gateway of last resort is not set 10.0.0.0/8 is variably subnetted, 2 subnets, 2 masks C 10.0.0.4/30 is directly connected, Ethernet0/0 L 10.0.0.5/32 is directly connected, Ethernet0/0 172.16.0.0/16 is variably subnetted, 5 subnets, 2 masks O 172.16.0.0/30 [110/20] via 172.16.0.9, 00:27:46, Ethernet0/2 [110/20] via 172.16.0.5, 00:27:36, Ethernet0/1 C 172.16.0.4/30 is directly connected, Ethernet0/1 L 172.16.0.6/32 is directly connected, Ethernet0/1 C 172.16.0.8/30 is directly connected, Ethernet0/2 L 172.16.0.10/32 is directly connected, Ethernet0/2
05-24-2018 03:07 AM - edited 05-24-2018 03:08 AM
So R4 and R4 do not have routes to the IPs you have used for the neighbor IPs.
You need to advertise the 10.0.0.x/30 subnets into OSPF.
Jon
05-24-2018 03:12 AM
05-24-2018 03:25 AM - edited 05-24-2018 03:43 AM
You could use statics although you would also need them on R3 as well or you can do -
R4
router ospf 10
network 10.0.0.0 0.0.0.3 area 0
passive-interface e0/0
R5
router ospf 10
network 10.0.0.4 0.0.0.3 area 0
passive-interface e0/0
Jon
05-24-2018 03:42 AM
Apologies, got that the wrong way round.
Have just edited previous post with correct details :)
Jon
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