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Community Member

EIGRP vs Static

I have an EIGRP range, 192.168.177.x, on a Cisco 7200 router.

The 7200 hands out 177 addresses via DHCP from it's ATM interface

Many of the 177 addresses are unassigned, at any given time.

But each address occupies a record in the EIGRP topology, as a directly connected device.

When I "show ip route" for any 177 network, there is a seperate route in

the EIGRP table for each individual address (not just one for the whole range).

Since there are 250 addresses in each network, that are "directly connected" via the ATM interface,

isn't this consuming a greater amount of bandwith than is necessary, with EIGRP routes?

I'm trying to capture any extra bandwidth I can in the network, so would I be better off with statics ?

Community Member

Re: EIGRP vs Static

Have you used the correct EIGRP network mask.

With your IP range you should enter the base network address along with the subnet mask and dependant on IOS version it will provide the correct network mask. This will summarise the routes for the 177 network.


Community Member

Re: EIGRP vs Static

Thanks for the input.

The EIGRP mask is


The "no auto-summary" command is in use. Would this be a problem ?

The individual routes also show up in the "show ip eigrp topology" output. I'm wondering what the effect of the topology on bandwidth.

The 177 example is just one...but there are actually 2 other networks, lets say 178 and 179, which make a total of several hundred directly connected devices, each holding its own space in the Eigrp topology.

Community Member

Re: EIGRP vs Static


The problem is no auto-summary. No auto-summary means it will not summarize the routes.. defualt nature of Eigrp is to summarize on major network Boundaries,but if you give the command no-auto summary it will not summarize.

So remove the command No-auto summary and check..

It will help you out..

Rate the post if find it useful..



Hall of Fame Super Gold

Re: EIGRP vs Static


While going back to auto-summary might fix the symptoms being described, there might be reasons why that network needs no auto-summary in the EIGRP process. And I believe that there is a better solution available. I faced a similar situation in configuring routers for dial access usage. They have a pool of addresses handed out by ppp negotiation and each individual address shows up as a connected /32 route. I solved it by configuring ip summary-address on the interfaces connecting to the rest of the network. This advertises a summary for this address range and does not advertise the individual /32 routes and it leaves IEGRP with no auto-summary (and in the network where I did this we needed no auto-summary because of discontiguous subnets).

I suggest that the original poster try configuring ip summary-address on the interfaces connecting to the rest of the network and let us know how it works.



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