Supernet routing

Hey guys, im unsure if im posting in the right place here, but i need a bit of clarification on supernetting. I cant seem to find anything related to it on the alternative menu.

now i know, using the 'ip classless' command in CISCO IOS software, global config mode, its possible to define a route to cover a range of subnets (a supernet route)

Would i be right in saying a valid supernet route for 192.168.64.0 /20 and 192.168.32.0 /20 would be 192.168.0.0 /16 :

I thought i'd nailed subnetting but im unsure of this.

regards to all and thanks in advance!

Well... if you don't care about what else is there in that space then that will work...

192.168.32.0/20 includes all everything from 192.168.32.0 to 192.168.47.255

192.168.64.0/20 includes everything from 192.168.64.0 to 192.168.79.255

These two /20 subnetwork doesn't really summarize well because they are not continguous. You still have another /20 between the two /20 you mention. However, if you don't care what is really there... and you just want to summarize it with one statement, 192.168.0.0/17 will summarize everything from 192.168.0.0 to 192.168.127.255 which includes the IPs you want.

Hey guys, im unsure if im posting in the right place here, but i need a bit of clarification on supernetting. I cant seem to find anything related to it on the alternative menu.

now i know, using the 'ip classless' command in CISCO IOS software, global config mode, its possible to define a route to cover a range of subnets (a supernet route)

Would i be right in saying a valid supernet route for 192.168.64.0 /20 and 192.168.32.0 /20 would be 192.168.0.0 /16 :

I thought i'd nailed subnetting but im unsure of this.

regards to all and thanks in advance!

ok cheers for that. seems like ive finally got subnetting theory down but could you elaborate for me as to what you were trying to explain? did i step on some reserved addresses or something?

Thanks!

What he says,

Is you are summarizing the subnets towards 1 big subnet, but this 1 big subnet also includes ip's not in your range.

this would almost be as summarizing :

10.1.0.0 /16 and 10.2.0.0/16 towards 10.0.0.0/8 (also including the 3-254 subnets).

You don't have a 10.3.0.0/16 in above example.. but this is also included in the summarized subnet. If that doesn't matter, than your good to go

Hi again chojin , Thanks for clearing that up.

The example wasn't for anything practical it was just so i was clear i had understood supernet routing.

If im correct, using your example; supernet routing to 10.0.0.0/8 would be usable for networks 10.2.0.0/16 and 10.1.0.0/16 provided there were no other networks in the autonomous system on the 10.0.0.0/8 network... correct?

i can see how much a waste that would be though lol, so many subnets would get flooded. :shock:

Cheers!

quick note: at time of giving that example my only intention was to cover the whole network 192.168.0.0

i realise it would cause too much traffic to be practical, but in theory wouldn't every node with 192.168.*.* designated to its ip address receive the packet?