Tasks
Note: You must perform Lab7 for loading the initial eBGP Multihop configurations before starting this lab.
● Create a new Loopback1 interface on R8 with the IPv4 address 204.12.8.8/32, and advertise it into EIGRP.
● Configure an EBGP peering between R8 and R9 in AS 54 using this new interface as the source of the peering.
Configurations
R8:
enable
configure terminal
!
interface Loopback1
ip address 204.12.8.8 255.255.255.255
!
router eigrp 100
network 204.12.8.8 0.0.0.0
!
router bgp 100
neighbor 177.1.79.9 remote-as 54
neighbor 177.1.79.9 ebgp-multihop 255
neighbor 177.1.79.9 update-source Loopback1
!
end
!
write
!
R9:
enable
configure terminal
!
router bgp 54
neighbor 204.12.8.8 remote-as 100
neighbor 204.12.8.8 ebgp-multihop 255
!
end
!
write
!
Verifications
As seen in previous output, the default TTL for EBGP peers is 1. This means that non-directly connected EBGP peers cannot be established, because the TTL will expire in transit. By issuing the ebgp-multihop [ttl] command, the TTL can be increased to support this type of design:
R8#show ip bgp summary | include 177.1.79.9
R8#show ip bgp neighbors 177.1.79.9
Note that the TTL must be large enough to reach the destination address. If Loopbacks are used, even if the routers are directly connected, the TTL must be at least 2 because the Loopback interface is considered one hop away from the physical interface.
