New cable modem - no sharing

I have two PCs that have been able to share printers and files until we recently had to replace the cable modem. Now they can't "see" each other, the only difference I can see is that now their IP's differ in the third octet, that is AAA.BBB.CCC.DDD, CCC is now different. One is running win 98 the other Win 2K.

 

Should add that the subnet mask is 255.255.252.0

 

That third set of numbers is the problem, they need to match. Only the fourth set should be different. The subnets should also match.

 

The third octet is probably your problem as KevinSaul said. But with a netmask of 255.255.252.0, only part of the third octet needs to match. Sort of.

The netmask tells your network which part of the IP address is the "network" and which is the client address. For the PCs to talk without a router, they all have to have the same address in the network portion.

The netmask needs to be in binary for it to make much sense though. The part that matches a binary number 1 is network, the part that matches a binary number 0 is client.

Thus 255.255.255.0 is 11111111.11111111.11111111.00000000 and in that case, the only variation allowed is in the 4th set of numbers (4th octet).

But 255.255.252.0 is 11111111.11111111.11111100.00000000 which allows you to have more client addresses than the 253 you have with the top netmask.

For instance, with that netmask you could use 192.168.0.1 <--> 192.168.3.254 and have the PCs on the same network (but avoid 192.168.x.255). However, 192.168.4.1 would be on a different network and not seen by PCs on the 192.168.0.x <--> 192.168.3.x network.

 

Thanks for the replies. I guess my third octet varies too much and a call to my provider didn't help, they say they can fix it. Guess I'll have to buy a router.

 

Just to follow up on this, I got a router and was able to share folders and printers. It wouldn't work until I installed the NetBUI and IPX/SPX protocols, as suggested by an FAQ at the router support site.

Thanks for the help!

 

One last followup on this, I had to get rid of the router but networking still works even though the third octet is different for the two PCs. I guess installing the Netbui and IPX protocols was the trick.

 

Neither NetBeui nor IPX uses or even understands IP addresses. Don't even see them.

And as a BTW - no problems on a small network running both those protocols but you probably only need one or the other rather than both. For your situation NetBeui is probably the best choice since it cannot and will not cross your router while IPX/SPX can and does which might leave a little security hole.

 

Took out IPX/SPX and things still work.

Thanks!

 

Glad to hear it.