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Question NB71 - EIGRP Summarization - contiva - 12-01-2009
Hi,
I'm confused to the correct answer on this one. The correct answer according to H2P is 10.10.10.0/24 and 172.16.0.0/16
surely if RT2 is summarizing then 10.0.0.0/8 is correct as it will summarize at the classful level.
I checked this on packet tracer and GNS - both times RT3 has 10.0.0.0/8 & 172.16.0.0/16 in routing table.
Is H2P answer incorrect?
Re: Question NB71 - EIGRP Summarization - b_rasheed - 12-14-2009
The auto-summarization in RT1 Router is disabled, this means RT3 and RT2 routing table will have 10.10.10.0/24 and 172.16.0.0/16 but if auto-summarization is enabled on RT1 then RT3 and RT2 routing table will have 10.0.0.0/8 & 172.16.0.0/16
make sure your configurations is correct on RT1 auto-summarization is disabled , RT2, and RT3 auto-summarization is enabled.
Thanks.
Re: Question NB71 - EIGRP Summarization - b_rasheed - 01-07-2010
contiva,
now I am confused too about this question RT1 is disabled so the answer should be 10.10.10.0/24 and 172.16.10.0/24, you right about your post.
I think we need the Admin to answer this question and eliminate this confusion.
Thanks.
Re: Question NB71 - EIGRP Summarization - dmick - 01-07-2010
I just looked this up and think I can clear up the confusion. According to Cisco Academy material:
"An EIGRP router autosummarizes routes ONLY for networks to which it is attached"
So, RT1 (no auto-summary) sends the 10.10.10.0/24 network to RT2. RT2, since it is NOT attached to 10.10.10.0 (or 10.0.0.0 for that matter) passes the classless address to RT3. It does not auto-summarize the 10.10.10.0/24 network because it is not attached to that network.
Hope that clears this up.
Re: Question NB71 - EIGRP Summarization - dmick - 01-07-2010
Maybe I should simplify my above response:
The 172.16.0.0/16 is auto-summarized by RT2 because RT2 is connected to that network.
The 10.10.10.0/24 is NOT auto-summarized by RT2 because RT2 is NOT connected to that network.
Re: Question NB71 - EIGRP Summarization - b_rasheed - 01-08-2010
Thank you dmick for the clarification, now it makes more sense.
Re: Question NB71 - EIGRP Summarization - contiva - 01-29-2010
Thanks for clearing that up. it was a great help