EIGRP Summary Address Problem

[mnlatif]

Hi,

On our core Router we have some 10.x.0.0 networks being received , more specficially 10.9-15.0.0.

A eigrp summary address was defined on one of the EIGRP interfaces as (for advertising to other internal EIGRP routers)

+++++++++++++++++++++++++++++++++++

ip summary-address eigrp 1 10.8.0.0 255.248.0.0 5

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The above command introduces a route similar to

10.8.0.0/13 through Null0 , while other more specific individual routes are still present in the routing table (E.g. 10.10.0.0/16 through x.x.x.x). This works Ok, till one of the node goes down and that particular routes dis-appears from the route table. At that time the router starts dropping the packets for that network (probably forwarding to Null 0 interface) instead of using the default route.

E.g.

If 10.10.x.x disappears from the route table then packets to that destination don't get forwarded through the default route.

Is this some design problem ?

Will defining a floating static route for all the summarized networks can solve this problem ?

Regards,

Naman

[thisisshanky]

Naman,

Thats normal behaviour. If a specific route is down, whats the point in routing the packet based on a default route to the next hop which will any way drop the packet, because the specific network is down.

HTH

Sankar.

[mnlatif]

Hi Sankar,

The reason i want to the packet to go to the default route is because that is a PIX and from there it will be going over a VPN link, which is a failover to our WAN link.

\\ Naman

[thisisshanky]

You may change this behaviour by adding a floating static route for each specific route. (next hop pix)

[pkhatri · Accepted solution]

Hi Naman,

In that case, you can try the following:

ip summary-address eigrp 1 10.8.0.0 255.248.0.0 255

That will summarise your networks but not install the summarin the routing table. The alternative, of course, is to configure a bunch of floating static routers.

Hope that helps - pls rate the post if it does.

Paresh