14 Replies Latest reply: Sep 29, 2009 9:17 PM by Vybhav Ramachandran RSS

    Dual HUB, Dual DMVPN Configuration help

    Vybhav Ramachandran

      I'm trying to implement a Dual hub, dual DMVPN topology. This is my topology.




      Hub1 and Hub2 are the two DMVPN hubs which are connected to the internal network ( /24 ) . SPOKE1 and SPOKE2 are the 2 spokes.R7 is just a router that is connected all the routers together.


      When i try a SHSD deployment ( Single Hub, Single DMVPN ), it works fine.

      However when i try this, i keep getting a wierd error message on SPOKE1,

      Which is as follows :


      *Mar  1 00:09:04.307: IP-EIGRP(Default-IP-Routing-Table:100): Neighbor
      not on common subnet for Tunnel1


      What's happening is that ( Hub2's tunnel IP ) from EIGRP 200 is mixing with the EIGRP 100 networks . What do i do to avoid this.

      As a result of this i'm not able to establish a DMVPN tunnel to either HUB1 or HUB2. For now, SPOKE2 configuration is empty. I have'nt configured it yet.

      I'm attaching all the configurations . Please let me know what can be the problem.


      My theories are :

          1) If we replace R7 with a switch and if we use different VLAN's for the links between the swx and the Hubs, then maybe we can achieve segmentation and this might prevent the EIGRP networks from clashing on the spokes.

           2) Maybe we should use sub-interfaces on the spokes ( serial ). But i asked one ccie-security and he told me that, DMVPN is agnostic to physical medium.


      Please let me know what you think might solve the problem?