summarizing addresses

[carl_townshend]

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 ?

[Harold Ritter]

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,

[carl_townshend]

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

[carl_townshend]

can anyone help me on this ?

[rawatmohinder]

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