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Community Member

no auto summary

when I use this command on my router, say I am advertising a 10.1.0.0/16 network, will other routers see it as 10.0.0.0/8 ?

5 REPLIES
Community Member

Re: no auto summary

no auto summary is used with only RIP, EIGRP and IGRPP router.

>if you are using rip version 1(classful protocol), it can't adverstise a subnet mask in the routing.

>if you are using rip version 2 or eigrp (classless protocol), the router will advertise the subnet at classfull boudary.

But with eigrp, you can summarize manually on interface.

Please don't forget to rate this post.

Regards.

Community Member

Re: no auto summary

Hi there I will be using eigrp on this router, can you tell me what this will be advertising to my other networks ? will it be 10/8

Re: no auto summary

Hi Carl,

Nice to see that you have started appreciating and rating all the posts.

If you are using EIGRP, bydefault auto summarisation is enable so it will advertise as /8 but if you issue a command "no auto summary" under eigrp process it will advertise as /16.

Have a look at this link for clear understanding with topolgy and example for auto summarisation

http://www.cisco.com/warp/customer/103/eigrp-toc.html#auto

HTH, if yes please rate the post.

Ankur

Community Member

Re: no auto summary

Hi Ankur

I cant open the doc, thanks, if I advertise a 10.1/16 address on my router and use no auto-sum on that router, another router has learnt this subnet but has auto sum switch on, would the router after that just see the 10/8 because it has auto sum on ?

Re: no auto summary

Hi Carl,

EIGRP performs an auto-summarization each time it crosses a border between two different major networks.

So answer to your question is YES the router after that where auto summary is not diabled will advertise it as 10/8.

Try to open the link again as I made it public link now

http://www.cisco.com/warp/public/103/eigrp-toc.html#auto

HTH, if yes please rate all post.

Ankur

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