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3620 to 3845 connection, NM-2FE2W-V2 incompatibility discovered?
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I recently replaced a 3640 router with a brand new 3845 and one of my
WAN links is a 100Mbps fiber optic link, lit with Transition Networks
media converters. It worked fine when a dedicated interface port on
the the 3640 was connected to a dedicated port on the 3620 across the
fiber link. Both the 3640 and 3620 have the old "version 1" NM-2FE2W
dual 10/100 network modules in them. My new 3845 has NM-2FE2W-V2
modules and it seems that the old style and the new V2 interfaces
refuse to talk to one another. I tried every combination of speed and
duplex setting at each router's respective interface (this is a
router-to-router dedicated link) and also ever possible combination of
speeds and duplex setting on the fiber optic media converters in
conjunction wih all possible speed and duplex settings on the router
interfaces themselves.

What I would get would be that the link would come up for about 120
seconds, carry traffic for that short while, and suddenly the interface
on the NM-2FE2W-V2 would shut itself down and the link LED would go
dark. There are no messages in either router's logs complaining of
duplex mismatch or any other messages giveing any clue other than
simple the "Interface FastEthernet1/0, changed state to down" message.
This does not happen when a "V2" interface talks to another "V2"
interface in the same router, but it seems like there may have been
some kind of limitation coded into either the firmware or IOS to make a
"V2" interface not compatible with an original "version 1" 10/100
interface... or is something else happening here?

The 10/100/1000 interface built into the 3845 has no problem at all
talking to the "v1" 10/100 interface in the 3620 router across the
fiber. That works just fine, but I hate using up a precious 10/100/1000
interface port for this router-to-router link when a plain 100Mbps port
would do just fine.

Anybody else encounter this strange problem?

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