question about EIGRP

Unanswered Question
Jun 29th, 2010

Hi !

I'm currently studdiyng for BSCI certification exam. For my final preparation I use some practice exam to verify my knowledge before going to the test center.

I'm not sure what I should understanding in this answer.

The summary route will be source from the RT1 Null0 interface in the routing table.

The question was about a network on which auto-summarisation was enable for the EIGRP process, which is route network and A summary address is configured on the interface serial 0 for adversting to it's neighbor.

My understanding problem is probebly rely on my primary language is not English. Can someone help me to understand the answer provide.

Thanks a lot !

I have this problem too.
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Mohamed Sobair Tue, 06/29/2010 - 07:44


Here is the concept for both (Auto Summarization & Summary Address) in Eigrp:

1- Auto Summary:

When (Auto Summary) is enabled, Eigrp performs summarization between major Network boundaries, lets assume you have 2 Networks and, and you have enabled auto summarization in eigrp. all Network routing updates from the 172 segment towards Network 10 will be summarized to its major class which is (since its class B) and all Network routing updates from 10 towards the 172 Boundary will be summarized to its major class which is (since its class A).

2- Summary Address:

When a summary address is configured per interface in Eigrp for an exist componenet subnets, a summary route pointing to Null0 interface is created in the routing table. This summary address is used to prevent loops in Eigrp. However the Summary is not sourced from the Null0 , The summary is generated for the components subnets as advertised to any Eigrp neighbor configured with a summary address.




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