[ale] Why would a uverse ethernet work but not a switch?

[Derek Atkins]

Hi,

Alex Carver via Ale <ale at ale.org> writes:

> It might still be a firmware update that at first didn't have VLAN
> support and then later did.
>
> If you want to really test it, gather everything up together in one
> location and replicate the configuration you have (TV + Router into
> switch, switch into modem) with short patch cables.  If all works well
> then yes you've got a broken wire in the infrastructure wiring.  If it
> doesn't work you've got a VLAN problem.

When I connect the switch directly to the router locally, the link
lights up (i.e, I get blinky lights both on the router and on the switch).

When I connect the switch through the wall, the link lights do NOT
illuminate, either on the switch or on the router.

A VLAN misconfiguration would not cause this behavior.

> It's also strange to see that your in-wall wiring is two pairs but wired
> to 8p8c jacks?  Is it unshielded twisted pair (CAT3) or is it a bundled
> run (straight wire) meant only for voice (in which case it should have
> been using 6p4c/RJ12 connectors).

There are many many pairs of wires in there.  It's probably cat3 cable,
but there are probably 5-6 pairs in there.  There is a single cable with
many pairs that goes into the box in the other room, and two pairs are
connected to the RJ45.

They need to use a 8p jack because it is ETHERNET.  Remember that at
least 100BaseT only requires 2 pairs, and I think GigE also only
requires 2 pairs.

I just don't understand why the switch is unhappy behind the 2 pairs but
my other devices are just fine.  I.e., it doesn't matter whether I plug
in the Uverse box or the Smart TV -- both of them work (individually) in
the other room.  But if I put the switch there, the switch wont sync to
the router.

-derek

-- 
       Derek Atkins                 617-623-3745
       derek at ihtfp.com             www.ihtfp.com
       Computer and Internet Security Consultant