The Journey of a Network Engineer

Aug 27 2013   6:05AM GMT

How to configure Cisco DMVPN? Part-2

Sulaiman Syed Profile: Sulaiman Syed

In the previous entry, we saw how to configure a basic DMVPN network. Let’s see the effect of adding the extra multicast mapping on our network table, and EIGRP adjuncies.

DMVPN Network photo diagram_zpse823e5d5.png

Since CE4 was configured with multicast mappings for CE3, and vice versa. let’s see the complete tunnel configuration for clarification

interface Tunnel1
ip address
no ip redirects
ip nhrp authentication CISCO
ip nhrp map multicast dynamic
ip nhrp map
ip nhrp map multicast
ip nhrp map multicast
ip nhrp network-id 10
ip nhrp nhs
tunnel source FastEthernet0/1
tunnel mode gre multipoint

let’s see our routing table in CE4, do few ping tests. and lastly see the Eigrp neighbors

CE4#show ip route eigrp is subnetted, 4 subnets
D [90/297372416] via, 00:03:42, Tunnel1
D [90/310172416] via, 00:03:43, Tunnel1
D [90/297372416] via, 00:03:43, Tunnel1

Traceroutes to CE3, and CE2 loopback addresses.


Type escape sequence to abort.
Tracing the route to

1 96 msec 80 msec 100 msec


Type escape sequence to abort.
Tracing the route to

1 112 msec 100 msec 72 msec
2 144 msec 180 msec 152 msec

Eigrp neighbor table

CE4#show ip ei ne
IP-EIGRP neighbors for process 10
H Address Interface Hold Uptime SRTT RTO Q Seq
(sec) (ms) Cnt Num
1 Tu1 14 00:04:25 157 5000 0 10
0 Tu1 12 00:04:33 80 5000 0 7

Since CE4 had CE3 mapping, we can see how the traffic went spoke to spoke without the need of going to HUB, this will of course save bandwidth. While going to CE2, it had to travel to CE1 (Hub) as we didn’t add the multicast mapping for it. But even for CE4, and CE3 to communicate they should first establish connection to CE1.

In the next entry, I will add the authentication/ encryption of tunnels, and configure a dual Hub scenario. If you ever required the topology and configurations, just drop a comment!

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