Computers lose the network when plugged in to Cisco

[d.anthony.hadley_2]

I am replacing a linksys router with a Cisco 2610. The original setup is the linksys WAN interface is connected to a Toshiba cable modem. The Linksys LAN interface connects to a port on a BayStack 102 hub. All the computers plug in to all the other ports on the hub. When I switch over (from linksys to Cisco), the WAN part works fine (that is, internet access), but several computers on the LAN lose connectivity to the network, there are no icons in My Computer. All the other computers are fine. The computers are all statically configured, nothing changes on them. I rebooted them and still no connectivity to the network. From a "non-connected" station I can ping other computers but from other working computers I couldn't ping that one. Am I missing something on the config? Any ideas? The hub is just a dumb hub, there are no VLANs, etc. Any info would be appreciated.

[Harold Ritter]

It sounds to me that it might be related to the workstations not having the same subnet mask.

Hope this helps,

[d.anthony.hadley_2]

Thanks for the response. But the workstations are all configured the same, I double checked. It's only when I plug the ethernet cable in to the Cisco router that the problem occurs. There is one way IP connectivity from the affected workstation. It's one of those weird things that just shouldn't happen, but it does. Any other ides? Thanks.

[Harold Ritter]

Can you tell us again what troubleshooting steps have been taken thus far. If you can ping from one station to the other it means you vae two way ip connectivity (icmp echo request and reply).

When you do a ping between two stations on the same subnet and it doesn't work, look at the arp table on the station from which you initiate the ping and locate the arp entry for the ip address you tried to ping. Does it contain the MAC address of the WS, the router or no MAC at all. Is the interface of the router configured with te same subnet mask as all the WS?

Hope this helps,

[d.anthony.hadley_2]

I was mot able to ping the affected WS (Station A), but the MAC address was in the ARP table of the working WS (station B). From the station A, I was able to ping station B. I learned that stations A was owned by a guy who got a new computer (station C). He had changed the name of station A to something else and gave station C all the original info he had on station A. They are also running Zone Alarm and when we rebooted the machines, we kept getting zone alarm "add a new network" dialog boxes. In any case, I moved the interface to another ethernet port on the 2610 (it has an NM-4E) and rebooted the WSs at the same time. All is working now. But, don't know if it was the Zone Alarm, some residual naming conflict, or moving to another port. Thanks for the info.

[Harold Ritter]

It does look like it was an issue of duplicate IP address. I'm glad you got it working.