Hi,

we use an IP-range 10.130.60.X with a 255.255.255.0 subnetmask
(so 254 addresses)

I would like to add another subnet by changing the subnetmask.
of course I could use 255.255.0.0 but this isn't good for broadcast I think.

Something ideal would be:

10.130.60.X
10.130.61.X

What subnetmask do I need ?

search for subnet calculator !

What you really need is a router (a real one not a broadband router) between the two networks and leave it subnetted the way it is.

I wouldn't recommend it, but you could use the subnet mask of 255.255.240.0

this would put 10.130.60.0 and 10.130.61.0 in the same subnet.

the networks would be subnetting like so:

10.130.0.0 - 10.130.8.0
10.130.9.0 - 10.130.16.0
10.130.17.0 - 10.130.24.0
10.130.25.0 - 10.130.32.0
10.130.33.0 - 10.130.40.0
10.130.41.0 - 10.130.48.0
10.130.49.0 - 10.130.56.0
10.130.57.0 - 10.130.64.0 <- your new subnet
10.130.65 - 10.130.72.0
10.130.73 - 10.130.80.0
etc...

you lose the first and last address for network and broadcast addresses.

This will give you a total of 2046 nodes on your logical network. Like I said, i dont recommend it.

They are use for Router Port as broadcast address.
you can't say lose to them!

Well you certainly can't assign them to anything To me, that means they're lost

Tnx alot Hillg3 !

I'll keep that in mind

Happy newyear !

How can you use Router without those address on the router nodes!
I guess i am talkin about High End Routers!

Dude what EXACTLY are you trying to do? Why do you think/want to run a different network other than your current one? Are you running out of addresses??

IMO, if you want some real help with your networking concerns, go to The experts-exchange website. You'll get much more professional responses by folks who know something, and without getting any insecure, insulting, childish responses. It's professional grade help.

^ I am quite sure I know what I'm doing when it comes to networking. But from the question asked, it would seem the poster is lacking even the basics. So how is asking the man for more detail of what his trying to do not professional?

Does he just need more hosts on his current wire, ie change the mask. Or should he route between segments? How many more hosts are we talking? Too many hosts on one wire may degrade his performance, would depend on his hardware setup and type of traffic, etc.. Shoot depending on his system, why is he not using the classful mask of 8 bit for his 10.x address scheme? Is he talking to other private networks?

Depending on what he is attempting to do - changing the mask could quite easy BREAK some connectivity. I would guess he has other connections - or did he just pull the 10.130.60 address scheme out of his ass? If he changes the mask, with not understanding the address space around him, possible changes to routing, etc.. He could quite easy overlap an existing network - and not only have issues with is local machines, but the network he steps on may have issues - or people connecting to them, etc..

Nothing against experts-exchange, but I am quite sure there are more than a few people here that can help him.

Yes, and I was talking about home routers, which technically aren't routers. On a Cisco router, assigning the first address of any subnet to an interface is custom