Route Summarization ?

Answered Question
Feb 6th, 2008

Hi,

Can someone check if I am getting this right ?

If I have the following networks:

172.16.1.0/24

172.16.2.0/24

172.16.3.0/24

Then the best summary address is

172.16.0.0/22

And if my networks to summarize are:

172.16.11.0/24

172.16.12.0/24

172.16.13.0/24

Then my summary address will be:

172.16.8.0/20

And if my networks to summarize are:

172.16.14.0/24

172.16.15.0/24

172.16.16.0/24

My best network summary address is :

172.16.0.0/19

Regards,

Phil.

I have this problem too.
0 votes
Correct Answer by Collin Clark about 8 years 9 months ago

1. I would agree with you

2. You could do a /21

172.16.8.0 255.255.248.0 Networks 172.16.8.0 to 172.16.15.0

3. I would agree again

HTH

BTW- A great tool for subnetting/summarizing is Solarwinds IP Subnet Calculator (and it's free) http://www.solarwinds.com/products/freetools/free_subnet_calculator.aspx

HTH

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philipbarker Wed, 02/06/2008 - 09:22

2 ... You could do a /21

I was a bit worried for a moment, but I only wrote 7 bits out instead of 8 when working this one out giving /20 instead of /21.

Thanks for your help and the calc link.

Cheers,

Phil.

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