EIGRP

[DanielBowen]

Can somebody explain to me EIGRP summarization? I understand what summarization is and the commands to configure it, but what I am unsure of is exactly what I am configuring into the router.
For arguments sake, if I have two interfaces:

FE1 - 161.76.8.1/24
FE2 - 161.76.9.1/24

am I configuring on each interface the following command?

router(config-if)#ip summary-address eigrp 100 161.76.8.0/23

am I on the right tracks?

Thank you in advance

Daniel,

 

[svermill]

No, I don't think so. It is a little difficult to explain without graphics. Essentially, you can manually summarize what is *behind* a router at an interace. For example, if you were running EIGRP with your ISP, you could summarize all of your subnets into one supernet. But you don't generally summarize parallel networks. Also, you aren't *required* to manually summarize. There should be a compelling reason to do so (such as the rather far-fetched one I mentioned above).

Scott

 

[wybnormal]

I will add that unless the network is VERY cleanly designed from an IP subnet prespective, you almost always turn OFF auto-summerization. Otherwise you might find your packets going completely the wrong direction.. I found this out the hardway at a client's site with over 900 EIGRP routes and one little dinky 1600 was installed with auto-summerzation enabled.. boy.. what a mess that made.. what a mess to troubleshoot!!! and no, I was not the one who put it in place..whew!!

MikeS
Find me at

http://www.packetattack.com

"The trouble with giving up civil rights is that you never get them back"

 

[saleen351]

the only time you want to summarize is when you have a "continiuos" subnet range. it there is a break in the subnetting allocation, then you cannot summarize.
e.g
10.1.0.0 thru 10.1.255.255

 

[saleen351]

eigrp auto summarizes by default, unless you explicity tell eigrp not to summarize using the no auto summary command