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incognito_54
Beginner

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.

1 ACCEPTED SOLUTION

Accepted Solutions
Jerry Ye
Cisco Employee

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

View solution in original post

8 REPLIES 8
Jerry Ye
Cisco Employee

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

View solution in original post

Jon Marshall
VIP Community Legend

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

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

peter.mainwaring
Beginner

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 :-)

incognito_54
Beginner

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.

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

Guys,

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

Inc.

Thank Jon for correcting my typo.

Regards,

jerry