DMVPN hub and spoke & spoke to spoke

[salman abid]

Hi

i was trying to practise DMVPN full-mesh on gns3....... i have configured R1 as HUb and R2 as SPOKE2.............i have just configured these two routers

but after completing the configuration i'm facing some logs on both R1(HUB) & R2(spoke2)

on HUB

*Mar  2 18:25:28.569: IP-EIGRP(Default-IP-Routing-Table:1): Neighbor 192.168.101.1 not on common subnet for FastEthernet0/0

on spoke2

*Mar  2 18:26:25.733: IP-EIGRP(Default-IP-Routing-Table:1): Neighbor 192.168.100.1 not on common subnet for FastEthernet0/0

it making me confuse

kindly some body check the attached topology & configuration

[Giuseppe Larosa]

Hello Salman,

you have configured EIGRP to run on the WAN facing fas0/0 interfaces but they are not in a common IP subnet and the error messages complain of this.

You need to remove the EIGRP network statements about 192.168.100.0 and 192.168.101.0

Then you need to change the IP address on spoke fas0/0 so that it is in a common IP subnet with the hub router.

You can advertise in EIGRP internal networks that you can define on the unused fas0/1 interfaces.

EIGRP must not run directly on the WAN interfaces.

DMVPN builds a logical flat network over the underlying IP internetwork and allows to advertise IP subnets that are internal to each participating device.

Hope to help

Giuseppe

[salman abid]

@Giuseppe

u want me to remove the network 192.168.100.0 & 192.168.101.0 from eigrp of both routers?????

and then assign the ip 192.168.100.2/24 to the fa0/0 of spoke2 router??? as well as assign the same subnet ip to other spokes and don't advertise this network to eigrp?????

m i right????

[Giuseppe Larosa]

Hello Salman,

>> u want me to remove the network 192.168.100.0 & 192.168.101.0 from eigrp of both routers?????

yes, EIGRP should run on internal networks and on the mGRE tunnel interfaces it should not run on the external "WAN" interfaces.

>> and then assign the ip 192.168.100.2/24 to the fa0/0 of spoke2 router??? as well as assign the same subnet ip to other spokes and don't advertise this network to eigrp?????

Yes, because you need to provide basic IP connectivity between GRE endpoint addresses and EIGRP has to run within the mGRE tunnels and not directly on the external interfaces

Hope to help

Giuseppe

[salman abid]

Hello

Giuseppe

as per ur instructions i have removed the eigrp process from the WAN links R1 & R2, also assign the same subnet ip 192.168.100.2/24 on fa0/0 of R2

but after doing this i'm getting some logs on HUB router that u can see in the above snapshoot

it seems tunnel is not stable!!!!!!!!!
kndly check & reply asap

[Giuseppe Larosa]

Hello Salman,

the tunnel should be stable.

Before the tunnel could not establish as there was no IP path between the WAN interfaces of R1 and R2 because it was a different IP subnet.

Check with

show ip nhrp

if you have stable NHRP entries

Also in EIGRP I would disable auto-summary at EIGRP process level

Hope to help

Giuseppe