RE: IPV6 Address Summarization

From: Joseph Brunner (joe@affirmedsystems.com)
Date: Thu Aug 30 2007 - 16:59:25 ART


Oops... I made the same mistake you did and got a /59

It is a /58 (DON'T FORGET TO PAD YOUR NIBBLES!!!)

12 is

00010010

25 is

00100101

So compare them

56th bit...00010010
56th bit...00100101

They match on bit 57 and 58... the last bit our summary...

So its

0000000000010010
0000000000100101

Its easiest when you count back from /64 (the end of the 4th 16th block)

So its 2001:141:1::/58

-Joe
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Sadiq Yakasai
Sent: Thursday, August 30, 2007 2:56 PM
To: Cisco certification
Subject: IPV6 Address Summarization

Hi Guys,

Please could someone help out a guy here:

I need to summarize these two IPV6 addresses:
2001:141:1:12::/64
2001:141:1:25::/64

I have done it many times over, and what I find to be the summarized address
is:
2001:141:1::/59

However, an excercise I am doing here says is
2001:141:1::/58

Please can someone confirm if I am right or wrong here?

Thanks!!

Sadiq



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