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Why auto-summary is enabled by default with EIGRP protocol?

csco11502970
Beginner
Beginner

Why auto-summary is enabled by default with EIGRP protocol?

2 Replies 2

Jan Hrnko
Enthusiast
Enthusiast

Hi Chetan,

I don't know if there is an answer to your question, but I just want to let you know that auto-summary is disabled by default on the newer IOSes (15). I am not 100 percent sure what changed their mind about that. Auto-summary has its pros and cons and maybe they think that nowadays it causes more harm than benefit. (As most of the time you want the auto-summarization to be turned off).

Best regards,

Jan

Alessio Andreoli
Contributor
Contributor

Hi there,
It is enabled because EIGRP is the evolution of a fully classful routing protocol (IGRP) where summarising classes had a different meaning than for us today summarising subnets..
Important issuing

Router EIGRP as_number
No auto

Each single time you configure EIGRP. It is very unlikely you are going to use the auto summary command in the modern networks.

Hope this helps
Alessio

Sent from Cisco Technical Support iPad App

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