DMVPN supports three different versions called “phases”. In my first DMVPN lesson I explained the basics and the DMVPN phase 2 configuration and DMVPN phase 1 configuration lessons explain how to configure the first two phases.
This time, I’ll show you how to configure DMVPN phase 3. We’ll use the following topology for this:
We have one hub router and two spoke routers.
Configuration
The configuration of DMVPN phase 3 and 2 is very similar. Let’s start with the following DMVPN phase 2 configuration on all routers:
Hub(config)#interface Tunnel0
Hub(config-if)#ip address 172.16.123.1 255.255.255.0
Hub(config-if)#ip nhrp authentication DMVPN
Hub(config-if)#ip nhrp map multicast dynamic
Hub(config-if)#ip nhrp network-id 1
Hub(config-if)#tunnel source GigabitEthernet0/1
Hub(config-if)#tunnel mode gre multipoint
Spoke1(config)#interface Tunnel0
Spoke1(config-if)#ip address 172.16.123.2 255.255.255.0
Spoke1(config-if)#ip nhrp authentication DMVPN
Spoke1(config-if)#ip nhrp map 172.16.123.1 192.168.123.1
Spoke1(config-if)#ip nhrp map multicast 192.168.123.1
Spoke1(config-if)#ip nhrp network-id 1
Spoke1(config-if)#ip nhrp nhs 172.16.123.1
Spoke1(config-if)#tunnel source GigabitEthernet0/1
Spoke1(config-if)#tunnel mode gre multipointSpoke2(config)#interface Tunnel0
Spoke2(config-if)#ip address 172.16.123.3 255.255.255.0
Spoke2(config-if)#ip nhrp authentication DMVPN
Spoke2(config-if)#ip nhrp map 172.16.123.1 192.168.123.1
Spoke2(config-if)#ip nhrp map multicast 192.168.123.1
Spoke2(config-if)#ip nhrp network-id 1
Spoke2(config-if)#ip nhrp nhs 172.16.123.1
Spoke2(config-if)#tunnel source GigabitEthernet0/1
Spoke2(config-if)#tunnel mode gre multipointTo migrate from DMVPN phase 2 to 3, we only need two commands…here’s the first command:
Hub(config)#interface tunnel 0
Hub(config-if)#ip nhrp redirect The NHRP redirect command on the hub will inform spoke routers that they can reach another spoke router directly. The second command is needed on the spoke routers:
Hi !
I didnt have “ip nhrp redirect” in my IOS (C3745-ADVENTERPRISEK9_SNA-M) ??? that´s the only one i got…
/Oskar
Hi Oskar,
Check the Cisco Feature Navigator to find out which IOS versions support certain commands.
It seems the T11 release for the 3725 should support ip nhrp redirect:
c3725-adventerprisek9_sna-mz.124-6.T11.bin
http://tools.cisco.com/ITDIT/CFN/Dispatch?act=featdesc&task=display&featureId=5963
Rene
Hello,
Should router do icmp redirection to his neighbors when they are in one subnet? This feature of IP protocol doesn’t work in this case, does it?
I see that you disable icmp redirects by issuing “no ip redirects” command on Tunnel interface.
Hi Rene, may be a trivial question but I have not played with GNS3 much. How do you simulate cloud like in this topology?
Hi Renee!
Great lesson as always
I was just wondering what about the “ip nhrp server-only” what is the purpose of the command??
-Dan