Best/fastes way to determine summary routes?

[CiscoBrownBelt]

So let's say I need to summarize everything from 192.168.3 - 192.168.250 does anyone know the statement to enter?

Also, what if I have other 192.168.X subnets that fall in that range that need to point to a different GW, is there any simpler way to do this (e.g. use a 192.168.0.0 255.255.0.0 X.X.X.X and just enter additional routes if something in 192.168.X.X has to be to a different GW)?

[Philip D'Ath]

Are you talking about static routes here, or a specific routing protocol?

[CiscoBrownBelt]

Sorry static routes.

[Philip D'Ath · Accepted solution]

The most specific route wins, so a more specific route than a summary route will be chosen.

The closest summary route to 192.168.3 - 192.168.250 is 192.168.0.0/16, which is 192.168.0.0 to 192.168.255.255.

ip route 192.168.0.0 255.255.0.0 ...

[CiscoBrownBelt]

Awesome thanks!

Do you happen to know of  a good route summary calculator?

[Joseph W. Doherty]

I suspect you understand you cannot summarize 192.168.3.0/24 .. 192.168.250.0/24 with just one statement without including other networks, e.g. 192.168.2.0/24.

You could, as you asked (and noted by Phillip), use more specific route statements to "override" the networks including in the summary that you don't want there.

You could also use multiple route statements to cover just the networks within 192.168.3.0/24 .. 192.168.250.0/24 (without, of course, one for every /24).

[CiscoBrownBelt]

Yes thanks Joseph W. Doherty and Philip D'Ath !

Basically, I have some subnets that need to go out other interfaces and yes they are let's say a 192.168.25.X or a 192.168.55.X, etc.

Nothing in an easy sequence and I just want to make my routing table/statements as clean and easy as possible. In a situation like this, I guess I will just have to enter a 192.168.0.0 255.255.0.0 (GW) and enter 192.168.X.X 255.255.255.0 for whatever subnets that need to go to another GW. 

[Joseph W. Doherty]

Yes, or again, the converse. Which would be the least number of routes would depends on what networks can be summarized together.

[CiscoBrownBelt]

Do you happen to know of  a good route summary calculator?