Cisco Support Community
cancel
Showing results for 
Search instead for 
Did you mean: 
Announcements

Welcome to Cisco Support Community. We would love to have your feedback.

For an introduction to the new site, click here. And see here for current known issues.

New Member

summarizing addresses

Can anyone please tell me how much I can summarize the 10.1.3.0/27 10.1.3.64/27 and 10.1.3.128/27 networks, I am using eigrp and want to summarize the best I can, would I just advertise the 10.1.3.0 network i eigrp, and could I summarize this down to say a /26 on my serial interface ?

4 REPLIES
Cisco Employee

Re: summarizing addresses

Carl,

the 27 mask would give you 32 address blocks. What about 10.1.3.32/27 and 10.1.3.96/27. Were you really referring to /27 or rather to /26?

If the latter, you could summarize the two first blocks (0/26 and 64/26) to 10.1.3.0/25.

Hope this helps,

Harold Ritter
Sr. Technical Leader
CCIE 4168 (R&S, SP)
harold@cisco.com
México móvil: +52 1 55 8312 4915
Cisco México 
Paseo de la Reforma 222 Piso 19
Cuauhtémoc, Juárez
Ciudad de México, 06600
México
New Member

Re: summarizing addresses

Hi there, thanks for your help, your right, It should of said /26 not /27, how would I summarize these then ? how did you work it out to a /25, can you show me how you did this ?

thanks a million

Carlos

New Member

Re: summarizing addresses

can anyone help me on this ?

New Member

Re: summarizing addresses

Hi Carl...

it is easy to summarise.

in summarisation you have to check the same number of high order bits.

10.1.3.0/26

10.1.3.64/26

10.1.3.128/26

so in binary it would be

10.1.3.00000000

10.1.3.00100000

10.1.3.01000000

so if you check that in fourth octet only first bit is same in all the address,so in subnet mask we can on the first bit to summarise all the subnets.

so summarised address will be...

10.1.3.0/25

Hope it hepls.

P.S:- Rate the post if find it useful.

Thanks

Mahi

115
Views
5
Helpful
4
Replies
CreatePlease login to create content