Strange situation

[dave7707]

I have a 1720 on a small network (4 users on a hub). When the users try to get to the Internet through the router, they can not. The users can ping the router but not beyond the router. From the router, I can not ping the users. After I clear the ARP, everything works ok. It will work ok for a while (15-30 minutes) then it repeats itself. I called TAC and they said everything looks ok, but to lower the ARP timeout. It didn't help. Any ideas?

[rbradfield]

It looks like that during the ARP request the wrong MAC address is being supplied by something! I have seen some UNIX servers do funny things like that.

Its strange you can ping from the PCs to the router and not the other way round!have you done an extended ping from the router?

Are you using NAT or anything,the router config might give a clue.

[dave7707]

It turned out to be a bad hub. We replaced it and everything is working correctly. Thanks for the reply though.