can anyone explain me about auto summarization?

kobem

when do we use it and why?

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kobem

please answer my question

forbesl

Go to the source:

http://www.cisco.com/en/US/tech/tk365/technologies_white_paper09186a0080094cb7.shtml#auto

kobem

hey i read some parts of it and there is a thing i didn't understand
is this :

we do auto summarize because they are in different networks
and also no auto-summary

what do i gain with doing summarization and not?

agustinchernitsky

You gain from Autoummarization when you do not have a discontiguos network... If you do have a discontiguos net, then autosummarization will prevent routing... this is when you have to issue the no auto-summarize cmd in RIP v2, IGRP and EGIRP.

Humper

Why bother replying to this guy, he needs to spend time reading the books and stop relying on the members of this forum for answers all the time.

loboernesto

(this is difficult to explain and difficult to understand, and what i'll write is my own understanding of it..I could be wrong, your will learn it properly by re-reading the concepts from different sources, try to find graphical explanations, they are much easier to understand).
Basically Auto-summary is a method used to minimize the size of your routing tables, as for benefits..I suppose you save router processing power and bandwidth (the bigger the routing table the bigger the routing updates), but it also can create routing loops (although this is prevented by the "null" interface created, at least on EIGRP) leaving you with some unreachable networks. Auto-summary is enabled by default with EIGRP and OSPF but can be disabled with no auto-summary. Look for the configuration examples in the cisco web. I hope I'm not confusing you more or guiding you in the wrong direction.. I'm not totally familiar with the concepts myself.
cheers

loboernesto

I answer because I think getting help and giving help is one the main purposes of a forum... and it helps me to learn things better. I find that by explaining things I get to understand and memorize them better.. And is not and obligation anyway.
cheers

mikej412

kobem wrote:

what do i gain with doing summarization

Route summarization reduces the amount of routing information in the routing tables.

loboernesto wrote:

you save router processing power and bandwidth (the bigger the routing table the bigger the routing updates)

And Memory.

The more entries in the routing table, the more routing updates you may need to send.

agustinchernitsky

ModemHumper wrote:

Why bother replying to this guy, he needs to spend time reading the books and stop relying on the members of this forum for answers all the time.

Well I agree he should try and read more before asking... on the other hand... we are here to help (that's the idea of the forum), if someone could/wants give him some orientation, he should.

My answer has a mix of both... I could grab or copy what cisco says... but instead I just said the "generall idea of what happens"... Of course he has to look deeper into books like we all do.

mikej412

ModemHumper wrote:

Why bother replying to this guy

Because it would make

happy?

Or maybe some scared newbie thinking about the CCNA stops by, we don't want to scare them off -- that's what subnetting is for.

Or maybe one of those MCSEs accidently clicks on a CCNA link..... we want them to get the "warm fuzzies" when they read our wonderfully helpful replies -- and plant the seed that maybe they should add a Cisco Cert or two their MCxx stash.

Or those Network+ people stop by and find all the help they need for their next cert (the CCNA) in one forum like they are used to -- rather then all those scary MS forums for all those confusing MS exams

And lets face it -- its a lot more fun to have something to look at when you take a break from work or studying. Yeah, I've noticed there is lots more activity here when you all should be working

-- I do it too, but usually when I'm working from home. You can always just

at the question.... and let someone else answer. The more "good activity" there is in a forum, the more likely others will join and post.

One of the things I liked about the forums here -- people here will take the time to post the link to the answer, rather than just a "google it" comment.

The Cisco Online Documentation is your friend -- but it isn't that friendly when you are just starting out. And then there is always the question -- Do you use this URL to start? Or do you use the Former Technical Documentation Site?

Oh oh!! Study break over! Back to the Rack!

Webmaster

mikej412 wrote:

Because it would make happy?

Seeing the forums serve its purpose does contribute to my happiness.

Mike pretty much said it all already, just wanted to add that trying to explain something can be very useful for those who don't entirely understand it themselves, or just want to check how well they know it. Though I prefer them a bit more specific than the question of this original poster, I rather see the forums filled with requests to explain a certain technology than the answer to a particular practice question. But of course the poster has to show an effort and willingness to learn.

mikej412 wrote:

The Cisco Online Documentation is your friend -- but it isn't that friendly when you are just starting out. And then there is always the question -- Do you use this URL to start? Or do you use the Former Technical Documentation Site?

Maybe we should add a short section to the CCNA FAQ, with some basic instructions for how to get the most out of the Cisco site /docs.

forbesl

mikej412 wrote:

And then there is always the question -- Do you use this URL to start? Or do you use the Former Technical Documentation Site?

You don't have to worry about which one to use....just go to the Cisco home page and type your query in the little "search" window at the top right hand corner of the page. Works every time. I'm all about using the K.I.S.S. principle.