Wednesday, 3 July 2013

EIGRP Summarisation and Default Network Advertisement

EIGRP Summarisation and Default Network Advertisement






  • Configure IP addresses for interfaces and loopbacks
  • Configure EIGRP
  • Configure EIGRP manual summarisation
  • Default Network Advertisement

Configure manual summarisation

If we take a look at the routing table on ZETA, we can see the routing table has seven subnets for the network being advertised from EPSILON. We can reduce the size of the routing table by creating a summary address for the subnets.

So we need to go on EPSILON to configure the summary address;

I will also do this for the loopbacks on ZETA;

You will notice the DUAL messages updating the topology table (see above). So now if we look at the routing table on ZETA the routes for the network should be summarised to

And for EPSILON the network has been summarised to;

Default network advertisement

I will now create a default network ( and propagate it through the EIGRP system, so that each router can see its candidate default network as the path with the shortest FD to the default network.

We can use the command show ip route to check if the default network is working. You can see the gateway of last resort is set to forward any traffic it does not know about to

If I try to ping a network my routers do not know about it will send it towards the default network as you can see this by using traceroute.


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