IP Addressing 1

[aimbc]

What would be the problem if the network id is 192.168.23.* and subnet mask is 255.255.0.0

The network seems to work ok but our router is not working that well.

We have two network one is 192.168.100.* and the other one 192.168.23.* Both have submask of 255.255.0.0 When this was the setup, everything worked great. I was able to get to computer on the 192.168.23.* network from 192.168.100.* network.

Now since we changed the address the subnet on 192.168.23.* To 255.255.0.0 it can not see the computer on that network any more.

I realize that the proper subnet mask for 192.168 (class C) should be 255.255.255.0 But changing the subnet mask to 255.255.0.0 (class B) and not changing the ip address to match the class B, can that be the cause of the problem?

Your help is appreciated.

Thanks,
Brian

 

[aimbc]

BTW we setup the NT server as a multihomed(router).

 

[chrisj01]

Brian,

First a simple subnet mask lesson, just in case you don't already know this. A subnet mask tells a device which part of the ip address is the network number and which part is the host number. So if you have an IP of 192.1.1.1 with a mask of 255.0.0.0 then routers, PCs, etc... will concider 192 the network and 1.1.1 the host. If you use the same 192.1.1.1 with a mask of 255.255.255.0 the devices will concider the network number to be 192.1.1 and the host to be 1. Make sense?

Now for your problem. By using the 255.255.0.0 mask you are tell the router that the network number for both your network is 192.168. This is probably why it won't route. It sees both ports as being attached to the same network so it kinda figures Host PC 23.* and 100.* are attach to the same hub so there is no reason to route anything.

If you will adjust your masks to 255.255.255.0 the router will now see two different network numbers and should route the traffic like your expecting.

If you really want to use 255.255.0.0 for some reason then change the second octect. For example use 192.168.23.* for one network and 192.169.100.* for the other. This way the network numbers are unique.

Make sense?

Gook Luck,

Chris

 

[globalstrata]

Check out at this helpful calculator. The explain buttons may help you understand a little bit better:

http://www.globalstrata.com/services/network/advnetcalc.asp

Gladys Rodriguez
GlobalStrata Solutions

http://www.globalstrata.com

 

[Serbtastic]

chrisj01, that was an excellent and easy to understand quick lesson on subnetting. Although I already understand how to subnet, I have yet to see if explained so simply.

Good Job! You get a star...