I can not ping from network to network but I can ping to directly connected interfaces. I am summarizing on HQ router.

I am trying to summarize the networks:

172.24.0.0

172.25.0.0

172.26.0.0

172.27.0.0

I am using command

ip route 172.0.0.0 255.252.0.0 10.0.0.2

I am slo trying to summarize the networks:

192.168.0.0

192.168.1.0

192.168.2.0

192.168.3.0

I am using command

ip route 192.168.0.0 255.255.252.0 10.0.0.6

Thanks Jon that worked perfectly. Just one question can you direct me to where I can get more info on route summarization?

Glad to help and thanks for rating.

Not sure where to go to be honest. I'll have a hunt around. When you summarise you can do it with binary but after a while it becomes easier to work it out in your head ie. in your example -

172.24

172.25

172.26

172.27

so you want to summarise the above 4 networks. We'll do it in the steps i took -

1) You need to summarise 4 networks. The first network is 172.24. Is 24 a multiple of 4 = yes.

2) Because 24 is a multiple of 4 you know that you can start with 172.24. and cover the next 3 network ie. 25,26,27

3) To get the actual subnet mask for 4 networks - 256 - 4 = 252. So the 2nd octet is 252

Lets assume another example to show how it doesn't always work as neatly. You want to summarise in one statement -

172.22

172.23

172.24

172.25

Using the same steps above -

1) 22 is not a multiple of 4. So you know that you cannot summarise this with a 252 subnet mask.

2) What is the next subnet mask up from 252 which covers 4 networks. It is 248 which covers 8 networks ie. 256 - 248 = 8

3) Will an 248 subnet mask work. Well if you go up in 8's it goes networks 0 -7 , 8 - 15 , 16  - 23 , 24 - 31, 32 - 39 etc.

4) Looking at the 4 networks you are summarising even that won't work because the 4 networks do not fit into one of the above ranges provided for by a 248 mask.

5) next subnet mask up is 240. 256 - 240 provides 16 networks. So your ranges are 0 - 15, 16 - 31, 32 - 47 etc..

6) So you can see that now the 4 networks fit in the range  16 - 31.

So 172.16.0.0 255.240.0.0 would cover your networks but it's important to realise you also cover a lot more networks ie. 172.16 - 21 & 172.26 - 31 are also included.

Note that i said it should be summarised in one statement. If you were prepared to use 2 you could do -

172.22.0.0 255.254.0.0

172.24.0.0 255.254.0.0

the reason i used one statement was i wanted to point out that just because you have 4 networks to summarise doesn't necessarily mean you can always just assume a 252 subnet mask.

Thats how i do it in my head. Hopefully that has helped although if it has confused you more i apologize.

Jon

Thanks for the info I will definitely put it to use.