Scenario:
The local hedgehog protection foundation is merging with the local Fox protection program. The networks are connected through BGP and part of the migration means you have to change your AS number. You don’t mind doing this but you don’t want to break the BGP neighbor adjacency.
Goal:
- All IP addresses have been preconfigured for you.
- Configure EBGP on router Sonic and use AS number 1.
- Configure EBGP on router Tails and use AS number 2.
- You have to configure router Tails with the “neighbor remote-as 100” command.
- Ensure your EBGP configuration is working.
IOS:
c3640-jk9s-mz.124-16.bin
Topology:
Video Solution:
Configuration Files
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The How to Master series helps you to understand complex topics like spanning-tree, VLANs, trunks, OSPF, EIGRP, BGP and more.
Written by René Molenaar - CCIE #41726
I downloaded the file,and checked it. But there is only interfaces configured in it.
Then I tried to do it myself.
On Sonic:
router bgp 1
neighbor 192.168.12.2 remote-as 2
On Tails:
router bgp 2
neighbor 192.168.12.1 remote-as 1
I remember that a router could run rip at first and then configure eigrp on it. After the eigrp learns the whole topology, you could delete the configuration of the rip without stopping the network. So I guess maybe I could configure “router bgp 1”, and then, “router bgp 100” finally, using “no router bgp 1”
But after I entered the command “router bgp 100”, it shows “BGP is already running; AS is 1″”
So would you please tell me the answer? Thanks 🙂
Hi Mao,
The key to this lab is the BGP “Local AS” feature. You can advertise a different AS number to a neighbor than the one you have configured with the BGP router process.
Rene
good lab.
also found the “dual-as” feature really interesting.
allowed Sonic to be in either AS1 or AS100… kool!
http://www.cisco.com/c/en/us/td/docs/ios/12_2s/feature/guide/fsbgpdas.html
router bgp 1
bgp router-id 1.1.1.1
bgp log-neighbor-changes
network 11.11.11.0 mask 255.255.255.0
neighbor 192.168.12.2 remote-as 2
neighbor 192.168.12.2 local-as 100 no-prepend replace-as dual-as