Leo Song wrote: > > Hi, there > > We met such a problem, while two Cisco 1720 routers and one > 3Com router > are interconnected via a share HUB, in a single collision L2 as > well as > L3 domain, the problem is somehow we can't PING the 3Com router > from any > of Cisco 1720 routers,
Is the 3Com router working correctly in every other way? Maybe the 3Com software rate-limits ping replies. > but the two Cisco 1720 router can PING > each > other, and we check the ARP table in the two Cisco 1720 routers > and they > does show up the correct APP entry for that 3Com router, and we > have no > access to that 3Com router (so we can't check its ARP table), > the only > thing about the 3Com router is it is correctly configured with > IP > address. Try an extended ping and make sure that the source address used by the Cisco router is the one for the shared Ethernet subnet that the 3Com is also on. Maybe the Cisco router is using a different address that the 3Com doesn't have a route back to. Is the Ethernet healthy? Are there lots of errors or other symptoms? Does show interface ethernet have any other clues? Can you put an anzlyer on the hub and check for errors as well as check the actual packets? > > And after we clear the ARP table in the Cisco 1720 router, then > the PING > to 3Com router is working but, after some time the PING > connectivity > between the Cisco 1720 routers and 3Com router was lost, That's very strange. But maybe sending the ARP restarts the rate limiting so it works for a while and then you reach the threshold again. > I > suspect that > is due the ARP problem, (incorrect ARP overwritten, in my > mind). Why do suspect that? Does it not show the MAC address that you expect for the 3Com router? > Would > you give me any hits on this problem without access to that 3Com > routers, and solution? I thought to place another Cisco router > to > replace that share HUB would be able to solve this problem and > it'll not > be cost effective. Thanks. If you replace a hub with a router, you'll have to redo your addressing. A router connects different L3 networks whereas a hub connects a single network usually. Well, I guess you could do bridging with the router instead of routing, and then you wouldn't have to change the addressing, but that would be an expensive "fix." Priscilla > > Best Regards. > Leo > System Engineer. > > Message Posted at: http://www.groupstudy.com/form/read.php?f=7&i=51433&t=51422 -------------------------------------------------- FAQ, list archives, and subscription info: http://www.groupstudy.com/list/cisco.html Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]
