GRE tunnel not coming up with DMVPN

[dimitri0s]

We are currenty trying to test a setup for GRE tunnels using DMVPN on a pair of 7200 routers using version 12.3(24a) acting as aggregators, a Catalyst 4948E L3 switch and an ISR 900 4G router.

When our tunnel is configured with DMVPN commands like :

interface Tunnel0
ip address 172.16.0.1 255.255.255.0
no ip redirects
ip mtu 1400
ip nhrp network-id 1
ip tcp adjust-mss 1360
tunnel source Loopback0
tunnel mode gre multipoint

it cannot get established and 172.16.0.1 is not pingable

when replaced tunnel mode gre multipoint with a physical IP address it got established.

Any thoughts?

[Jaderson Pessoa]

Hello

Loopbackp0 is up?

Post your configuration here.

Line Protocol Down Locally on the Router

Under normal circumstances, there are only three reasons for a GRE tunnel to be in the up/down state:  

• There is no route, which includes the default route, to the tunnel destination address.
• The interface that anchors the tunnel source is down.
• The route to the tunnel destination address is through the tunnel itself, which results in recursion.

These three rules (missing route, interface down, and misrouted tunnel destination) are problems local to the router at the tunnel endpoints and do not cover problems in the intervening network or other features related to the GRE tunnel that might be configured. This document describes scenarios where other factors might influence the state of the GRE tunnel.

[dimitri0s]

Hello and thanks for fast replying

Yes is up!

[Jaderson Pessoa]

post here output from:

show ip int brief
show running-config
show dmvpn

[Georg Pauwen]

Hello,

what you have posted:

interface Tunnel0
ip address 172.16.0.1 255.255.255.0
no ip redirects
ip mtu 1400
ip nhrp network-id 1
ip tcp adjust-mss 1360
tunnel source Loopback0
tunnel mode gre multipoint

is not nearly enough for any DMVPN, not even phase one, as you have no NHRP mappings. What does your topology look like, which router is the hub, which the spoke ?

[dimitri0s]

Thanks for your replies.

Eventually tunnel establishment didn't occur to one of the two routers due to older IOS version.

After struggling with an upgrade since they are old boxes with compact flashes, we managed to establish the targeted setup.