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igrp is not availabe with new software 12.3.Implement eigrp

we are currently running igrp on all routers at HQ and 6 remote branches.We've just purchased new router with new software 12.3 which removes igrp.Is there a way that we can change

all remote router from igrp to eigrp WITHOUT physically going to remote sites and MINIMIZE the downtime.Thanks all for the inputs.


Richard Burts
Hall of Fame Guru

You should be able to telnet (or SSH) to the remote routers and configure EIGRP on them without having to go to the remote site.

You probably want to run both IGRP and EIGRP together on the HQ router until you get all the remotes converted. You probably want to set up redistribution between IGRP and EIGRP on the HQ router so that all remotes maintain connectivity to each other. You may want to convert one remote at a time by configuring EIGRP on the remote and when EIGRP has stabilized and is advertising the routes from the remote then you can remove IGRP from the remote. I think that you should be able to convert the routing protocol without any down time.





Hi Rick,

Thank you very much for your input.Corret me IF i am wrong withthe following approaches:


step#1.configure EIGRP all routers at HQ

Step#2 Configure EIGRP all routers at remote Sites

Step#3 after all EIGRP routes are stabilized and then

remove IGRP routes.



There are THREE 2620xm routers at HQ and SIX 1751 at remote sites.CAN I configure all STATIC ROUTEs in EACH 2620xm routers to remote routers,When all routes are connected then remove IGRP and configure EIGRP.

Tell me if i am wrong with the following steps:

1. Create static routes in all THREE 2620xm routers point to remote sites

2. remove igrp (NO ROUTER IGRP 15) .At this point, all routes should still be able to communicate, RIGHT ? Please confirm!!!

3.Configure EIGRP (ROUTER EIGRP 15) in each HQ routers

network (HQ)

Network Remote site#1

Network Remote site#2

Network Remote site#3

Network Remote site#4

Network Remote site#5

Network Remote site#6

Network Remote site#7 (This is a new location with new router)

4. Remove all static routes from HQ routers ( NO IP ROUTE)

Do i need to disable (NO AUTO-SUMMARY) summarization ? Because my networks are NOT DISCONTIGUOUS.

Thank you very much.



As for Approach 1 there are several things to consider:

- as some remotes start advertising their networks in EIGRP do you want to redistribute those routes into IGRP?

- as you get some routers running both IGRP and EIGRP the Administrative Distance would normally make EIGRP more attractive. If you lower the Administrative Distance of IGRP to less than 90 then IGRP will still be the more attractive protocol, giving you an opportunity to verify EIGRP operations (forming correct neighbor relationships, etc) without impacting the routing table.

- when you start to remove IGRP you might want to remove it on all remotes before you remove it at HQ.

- I would not think that you would lose your telnet connections in this process. If you are concerned about the possibility of losing sessions then you might want to consider the possibility of scheduling reloads (reload at : or reload in ), so that if you have made changes, have not yet saved the changes to startup, lose your connection, then the scheduled reload will reboot the remote router and will load the startup config so your changes are gone and you are back to square 1. (It is cheap insurance for remote maintenance.)

As for appropach 2:

- Statics at HQ point to remote sites is fine. And you will also need to have statics at the remote pointing to HQ.

- each HQ router will need statics for each remote and may need statics for network segments connected to other HQ routers. The remote router can probably be ok with a default route pointed to HQ.

- if you have correct static routes and remove IGRP you should still have connectivity.

- in configuring EIGRP (and IGRP for that matter) you need network statements for your connected networks and subnets and you do not need network statements for remote networks. So depending on some details of your topology it may be that HQ routers will not need every one of the network statements that you listed.

If your networks are not discontiguous then I would be inclined to let auto summary work.

There may be some aspects of your topology that could impact your conversion plan including how the HQ routers are connected to each other, are there redundant connections from remote routers to HQ, are the links from HQ to remote addressed in HQ address space, in remote address space, or in some other network?





Hi Rick,

Again,thank you very much for your reply.You're really a big help.To answer your question, for the time being,there's NO redundant connections between remote and HQ locations.Here is our topology,Your input is greatly appreciated.

At HQ location:

Router#1 2620xm

Router#2 2620xm

Router#3 2620xm

Router#4 2620xm (This is a new router

with 12.3 software and will be configured with EIGRP.

Remote Locations:

Routers(1751) at Site1 and Site2; respectively.Connected to HQ Router#1

Routers(1751) at Site3 and Site4; respectively.Connected to HQ Router#2

Routers(1751) at Site5 and Site6; respectively.Connected to HQ Router#3

new Router(1751) at new site7 connected to HQ new Router#4


1. Do I only need to configure STATIC Routes from HQ router#1 to Site1 and site1 and vice versa,from routers site1 and site2 point back to HQ router#1.

Configure the others as similar fashion?

2.In configuring EIGRP. as you said, I only need to add NETWORK statements to direct connected networks.


Router#1(config)router eigrp 15




Router#2(config)router eigrp 15




Router#3(config)router eigrp 15




Router#4(config)router eigrp 15 (NEW ROUTER)



Routers at Remote sites:

Routers at site1&2(config)router eigrp 15



Same for all other remote routers.

This approach would work,Right?

3.How long do you think all routes will be propagated.




I am still not clear on some aspects of the topology:

- you describe HQ routers as,,, and which implies that they are connected on a LAN. Is that the LAN of HQ or is this the network on which they are connected?

- how are the remote routers connected to HQ? Is is some kind of serial link or what?

- it is logical that the remote routers are connected with an interface on a LAN and have some connection with another interface on whatever connects them to HQ. Can you lay out the various addresses being used?

- also can you clarify whether there is a single LAN at HQ or are there multiple segments in the network at HQ?

For the questions that you asked:

- 1) if you are going to turn off IGRP and use static routes as the temporary/conversion mechanism then each HQ router will need a static route for every network segment. This is assuming that a user at one remote may send something where the destination is another remote (any to any connectivity). If your situation is such that remotes only send things to HQ and never to another remote, then the situation is easier. But as I think about it there is also the situation where a user at site 1 sends something through HQ #1 which forwards it to a server at HQ. But the server default gateway is HQ#2, which needs a route back to site 1. So I was right the first time - each HQ router needs a static to every network segment.

- 2) each HQ router would also need

And I can not really say what network statements they need till you help me understand the IP addressing on the links that connect the remotes to HQ.

- 3) If you asking how long it will take for the advertisements to get advertised accross the entire network, I believe that when you type in the last configuration statement on the last router and go to the first router to look at it, the routing updates will be completed. (It sould be no more than a couple of seconds for the advertisements to propagate.)





Hi Rick,

Technically,these HQ and remote routers are on the same network.IT's like a STAR TOPOLOGY, all remote routers are connected to HQ routers (BACKBONE routers).In another words, the remote routers must pass through HQ routers and then PIX firewall,Premier Router to get out the INTERNET.

IT's a single LAN at HQ.Geographically, It's WAN,But located on the same segment.Hopefully,It clarifies my topoloy.If needed I will email you a layout of our network to help you better understanding.

Thanks again.



I am having some difficulty with the concept that the remotes are all in the same subnet as the HQ routers. If you want to email something to me my EMail address is (and my address is also included in my profile for NetPro forums).

Perhaps it would help if you would share the output of show ip interface brief from some (or all) of the routers.





I'd be inclined to just load EIGRP on the HQ router and then go to each spoke router and load EIGRP.

Check EIGRP neighbor relationships and topoloy table.

Disable IGRP on spoke site.

once all spokes are done, disable IGRP on the HQ.

If for some reason you lose connectivity (but you shouldn't) you could always telnet from the HQ router to the spoke router WAN IP address to fix. There is no route needed for HQ router to reach spoke router - they should be on the same network (the WAN subnet)

unless something has changed IGRP and EIGRP will automatically do mutual redistribution. I believe the IGRP routes are preferred.

decent getting started doc...

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