We help IT Professionals succeed at work.

Cisco GLBP, DHCP, and configuration sync

I have two (2) Cisco 2821 that I configuring for GLBP.  Two questions that I have:
1 - Since I'm running a DHCP server off my current Cisco 2821, how will the 2nd load balanced router behave?  Is it possible that it will assign a duplicate IP address?

2 - Is there a way to synchronize the cisco configuration?  Meaning, if I make a change on one router, will it be copied over to the others in the GLBP group?
Comment
Watch Question

No, GLBP is only used to load balance your gateway for traffic. there is not a way to sync any other part of the router config.

So if you loose the router with the DHCP service then your DHCP will be down. If you have both routers setup with the same DHCP config then yeah you might run into conflicts.

My suggestions are:

1) setup the second router with a second scope that does not overlap with the primary routers DHCP scope. So devices could pull from either scope and if one of the routers goes down all will pull from the router still up. The simplest way to do this is if you can setup both scopes within the same subnet so you do not need to change routes and such.

2) Setup a backup DHCP server on another device or the secondary router and deactivate. If you loose your DHCP router then enable the backup DHCP server. this is a manual process though.

DHCP is pretty limited on its features within Cisco IOS and you might be better off moving this service to a server such as Windows or Linux were redundancy is addressed better.

Hope this helps