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Community Member

Question on Subnets and Wild Card Masks

Hello's

I would like to request some help in summarizaing and wildcard masks.

I have the following subnets that i'd like to summarize and then use the summary address in an Access list. Is this possible?

Here are the ranges:

172.22.96.0/19

172.22.128.0/19

172.22.160.0/19

thanks

Inc.

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1 ACCEPTED SOLUTION

Accepted Solutions
Cisco Employee

Re: Question on Subnets and Wild Card Masks

How much summerization are you planning?

You can summerized them into a single /16

172.22.0.0 255.255.0.0 (reverse mask for ACL is 0.0.255.255)

or one /19 and one /18

172.22.96.0 255.224.0.0 (reverse mask for ACL is 0.31.255.255)

172.22.128.0 255.192.0.0 (reverse mask for ACL is 0.63.255.255)

Regards,

jerry

8 REPLIES
Cisco Employee

Re: Question on Subnets and Wild Card Masks

How much summerization are you planning?

You can summerized them into a single /16

172.22.0.0 255.255.0.0 (reverse mask for ACL is 0.0.255.255)

or one /19 and one /18

172.22.96.0 255.224.0.0 (reverse mask for ACL is 0.31.255.255)

172.22.128.0 255.192.0.0 (reverse mask for ACL is 0.63.255.255)

Regards,

jerry

Hall of Fame Super Blue

Re: Question on Subnets and Wild Card Masks

Jerry is correct in that you can summarise them with 2 entries -

172.22.96.0 255.224.0.0 (reverse mask for ACL is 0.31.255.255)

172.22.128.0 255.192.0.0 (reverse mask for ACL is 0.63.255.255)


note though that there is a typo - reverse masks should be 0.0.31.255 and 0.0.63.255

Jon

Community Member

Re: Question on Subnets and Wild Card Masks

I agree with Jon and use the following:

172.22.96.0 255.224.0.0 (reverse mask for ACL is 0.31.255.255)

172.22.128.0 255.192.0.0 (reverse mask for ACL is 0.63.255.255)

Regards,

Sal

Community Member

Re: Question on Subnets and Wild Card Masks

If I have worked this out correctly then you could do it with a wildcard of 0.0.224.255.

This will allow x.x.96.x, x.x.128.x and x.x.160.x

However, it also allows x.x.0.x, x.x.32.x, x.x.64.x, x.x.192.x and x.x.224.x , which you may not want.

HTH

Pete

PS - Any corrections welcome :-)

Community Member

Re: Question on Subnets and Wild Card Masks

I'm a little confused from the responses. Perhaps its the typo mentioned.

One of the responses given was 172.22.96.0  255.224.0.0 ...... Was this meant to be 172.22.96.0  255.255.224.0 with a reverse of 0.0.31.255?

The second response given was 172.22.128.0  255.192.0.0 ....... Was this meant to be 172.22.128.0  255.255.192.0 with a reverse mask of 0.0.63.255?

thanks again for your time.

Inc.

Hall of Fame Super Blue

Re: Question on Subnets and Wild Card Masks

Incognito_54 wrote:

I'm a little confused from the responses. Perhaps its the typo mentioned.

One of the responses given was 172.22.96.0  255.224.0.0 ...... Was this meant to be 172.22.96.0  255.255.224.0 with a reverse of 0.0.31.255?

The second response given was 172.22.128.0  255.192.0.0 ....... Was this meant to be 172.22.128.0  255.255.192.0 with a reverse mask of 0.0.63.255?

thanks again for your time.

Inc.

Yes it was meant to be -

172.22.96.0   255.255.224.0  - reverse mask 0.0.31.255

172.22.128.0 255.255.192.0  - reverse mask 0.0.63.255

Jerry just made a typo which is very unusual for him as he is normally spot on.

Jon

Community Member

Re: Question on Subnets and Wild Card Masks

Guys,

Thanks so much for your speedy responses. Much much appreciated.

Inc.

Cisco Employee

Re: Question on Subnets and Wild Card Masks

Thank Jon for correcting my typo.

Regards,

jerry

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