Can only the 100Mbs part of a 10/100Mbs router fail?

Larry Cook lcook at sybase.com
Wed Dec 8 08:19:01 EST 2004


I'm having a network problem that appears to be that the 10/100Mbs ports on my 
router are no longer working at 100Mbs, but are working at 10Mbs. Is it 
possible that just the 100Mbs part could fail?

Here's my scenario if anyone is interested.  Connected to the router are the 
following:

Computer #1 w/ 10Mbs NIC
Computer #2 w/ 10/100Mbs NIC (auto-senses to 100Mbs)
100Mbs switch

Computer #1 (10Mbs) works fine, but Computer #2 (100Mbs) and everything behind 
the 100Mbs switch cannot get to the router.  Switching ports on the router and 
power-cycling the router made no difference.

I put computer #2 (100Mbs) behind the 100Mbs switch and it can get to all 
computers behind the switch, but not to the router.  So this tells me that the 
NIC in computer #2 is okay.  It also seems to imply that the 100Mbs switch is 
okay since computer #2 can talk to another 100Mbs computer behind the switch.

If I replace the 100Mbs switch with a 10Mbs switch, then everything behind it 
can now get to the router, including computer #2 which auto-senses to 10mbs. 
But when I move computer #2 back to the router, it auto-senses to 100Mbs and 
cannot get to the router.

So the only thing that seems to explain my problem is that the 100Mbs part of 
my router has gone bad, although devices connecting to it are auto-sensing to 
100Mbs.  Or is there something that I am overlooking, or something else I 
should try?

Thanks,
Larry




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