Best approach to change EIGRP AS number?

[darrenriley5]

Hi,

I have a scenario where I may need to change the EIGRP AS number within my company. The network is pretty simple and eigrp is primarily used to support our branch network. What we are looking to do is share some branch infrastructure with a subsiduary and use vrf's to logically segment each business unit. The problem is both business units use the same EIGRP AS number so if my understanding is correct the EIGRP as number is associated with a vrf therefore I will need to change it unless I can do some route redistribution between a new AS and my current AS.

My thought process is to create a new EIGRP process on the core switches then connect to each branch router and change the AS. Only concern is at the branches if something went wrong I might not be able to connect to them and we have no IT staff at these sites.

Just after some tips for changing the AS number if anyone has any?

Many Thanks

[siddhartham]

what about using a reload in 15 command on the branch router and then change the ASN number- if everything works then you can connect to the branch router and do a reload cancel- if it fails wait for 15 min and the router will reload in 15 min and come back up with old ASN number and you can reach it.

Siddhartha

[Joe Lentine]

Your best bet is creating the new AS in your core with the exact config as your other AS. from there hit each branch router and you should be able to rebuild it without issues. you didnt give any amount of downtime but you would be looking at branch to branch failure for a certian amount of time. depending on how long you can config!

[sean_evershed]

One possibility is to leave he AS numbers as is.

You can then use route targets to export and import the necessary routes between the different VRFs.

In a standard MPLS VRF topology the core switches are P routers and only participate in the Global routing table. They provide a transit path between the PE routers.