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

[Brian]

Every 10/100 device I've seen in the last 10 years has used 1 chip to handle
the 10/100 PHY.  This means that it would be (IMO) HIGHLY unlikely that only
the 100Mbs portion could/would fail, I would expect all or nothing.

Based on past experience (is there such a thing as *future* experience?) I
would suspect the switch (I am assuming it's a cheapie Linksys type device?)
and/or the cabling.  

My suggestions would be to check/replace the cabling.  Move the switch
physically closer to the router, try plugging a PC directly into the router
(might need a crossover cable for this).

What are you usng for a router? 

-----Original Message-----
From: gnhlug-discuss-admin at mail.gnhlug.org
[mailto:gnhlug-discuss-admin at mail.gnhlug.org] On Behalf Of Larry Cook
Sent: Wednesday, December 08, 2004 8:19 AM
To: GNHLUG
Subject: Can only the 100Mbs part of a 10/100Mbs router fail?

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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