Having just recently done a migration from IGRP to EIGRP in a hub and spoke
network, I learned a few basic guidelines for the migration.
#1. Have a plan! I cannot tell you how many times I came across engineers
just wanting to just flip the switch and enable EIGRP without any
pre-planning. It is imperative that one understands the need for good
subnetting and summarization. Also, it is critical, that in the event of a
failure during the migration plan, you also have a back out plan.
#2. Do one location at a time. When you make a change, minimize variables.
Now, this step can be open for argument and it truly depends on your network
topology and your plan. The reason I bring it up is because it proved
useful in my hub and spoke network migration. What I did for each location
was to run IGRP and EIGRP with the same process number on the hub. When I
migrated a site, I enabled EIGRP, and verified the EIGRP routes were
propagating. Once verified, I disabled IGRP on the remote router and on the
hub side, under IGRP, I specified a passive interface for that
point-to-point sub-interface. It works well in my case because if a problem
arose, I could pin it down to one or the other routing protocol.
#3. After making changes, monitor for a decent period of time to determine
if everything went smoothly. For my changes, I picked 3 days. I had
international sites, so I needed to see data patterns across time zones.
#4. Document the hell out of what you did.
#5. Bonus! In my research, I also discovered that in the newer versions of
IOS, there is such thing as a "stub" network in terms of EIGRP. It allows
for maximum stability in a hub and spoke network. There is a great page on
CCO that describes it well:
http://www.cisco.com/univercd/cc/td/doc/product/software/ios120/120newft/12
0limit/120s/120s15/eigrpstb.htm#16026
<watch the line wrap>
Anyway, I hope my own experience can add to yours!
-Joseph
----------
>From: "Santosh Koshy" <[EMAIL PROTECTED]>
>To: [EMAIL PROTECTED]
>Newsgroups: groupstudy.cisco
>Subject: Re: Converting from IGRP to EIGRP
>Date: Wed, Feb 14, 2001, 5:42 PM
>
>> First, please do not put everything in the same AS.
>> This is a very bad thing, and I really wish Cisco
>> would kill the feature. (I think it was placed in
>> there for marketing)
>
> I dont get this robert.... Please explain the above...
>
>
>
>
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