Forums > General Discussion > Same Tunnel source for multiple DMVPN networks on a single HUB, possible?
mesla
2 posts
11 Jun 2012 at 4:22 a.m. UTC

Hi,

My situation is as follows:
One single Cisco 3845 as the hub router and 700 Cisco 878 branch routers over a common L3 MPLS network with EIGRP planned as the routing protocol.

I decided to create two mGRE tunnels on the HUB router with different tunnel key, different NHRP network IDs and different IP subnet but using same tunnel source interface on both tunnels. I'm doing this in order to support more than 350 EIGRP neighbors on DMVPN.

Is this possible using the "tunnel protection shared" command and supported or not?

thanks in advance,

Mohamad
stretch
274 posts
12 Jun 2012 at 1:18 a.m. UTC

You may want to take a step back and rethink your overall plan. DMVPN scales well, but a 700-spoke DMVPN with a single hub might not be the best design. I'd look into splitting it into more manageable segments or switching to a multi-tier topology.
mesla
2 posts
12 Jun 2012 at 3:53 a.m. UTC

Thanks for your reply. you are correct the plan has to be changed. I think as in the Cisco Design guide 1.1 using two tire topology using ASR or 7200/7600 series works for this case well.

Anyway I found several documents regarding DMVPN and EIGRP limits (up to 350-400 eigrp neighbors per interface), so my question: is it possible to use two mGRE tunnels on the HUB router to split the EIGRP neighbors using a shared tunnel source interface, different tunnel key, network ID and Subnets?(I tried this in GNS3, there was no problem but in real life I do not know the possible issues)

thanks again,

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