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

Tue Apr 9 22:51:39 EDT 2019

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.

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).

On 2019-04-09 18:47, Derek Atkins wrote:
> Interesting concept, but that doesn't explain why it was working for a
> month or more and just now failed.  Also, it does not matter which port
> on the router I use..  In all cases the TV works but the switch does
> not..  At least, it does not when I include the building wiring.  If I
> move the switch to the router and plug it into the same port (unplugging
> the other room) the switch works fine.  So I do not think it is the VLAN.
> I think it is the wiring.
> I just don't know what would cause the TV box to work but the switch not
> work over the building wires.
> 
> -derek
> Sent using my mobile device. Please excuse any typos.
> On April 9, 2019 8:27:24 PM Alex Carver via Ale <ale at ale.org> wrote:
> 
>> I believe that AT&T has been VLANing the TVoIP data.  An ordinary switch
>> that doesn't have VLAN capability may not be able to handle the mangled
>> 802.1Q tagged packet so it will just dump it on the floor instead of
>> routing it onward.  This would be why the Uverse box direct to the wall
>> works but not through the switch.
>>
>> You would have to sniff the packets to see what VLAN the TVoIP data is
>> on and what VLAN the normal connection to your router is on (this one is
>> most likely untagged) then replace your switch with a VLAN capable unit
>> and set up the ports accordingly.
>>
>> I have an AT&T modem as well (though my ATA is in the modem rather than
>> external) and occasionally in the logs I do see messages about VLANs.
>> However, I don't get TV service over the wire, I have satellite so I
>> don't have a TV box to play with.  My parents also have AT&T but their
>> TV box is wireless and connects to a wireless adapter plugged into the
>> modem so that might be another way out.
>>
>> On 2019-04-09 16:08, Derek Atkins via Ale wrote:
>>> Alan,
>>>
>>> Thank you for playing, but you are completely overthinking the problem
>>> (and not paying attention to what my problem is).
>>>
>>> First, there is an AT&T router that provides me a local 192.168 network
>>> and yes, it NATs, but that is irrelevant.
>>>
>>> It has 4 RJ45 ports and Wifi.
>>> One port is connected to the local Uverse TV box.
>>> A second port is connected to my ATA phone.
>>> A third port is open.
>>> The fourth port is connected to the building wire, which is connected to
>>> another room.  In that other room, if I connect my Uverse TV box
>>> directly,
>>> it works.  And up until a week ago, if I connected my switch and then
>>> connected the Uverse Box and my Smart TV to the switch, it all worked.
>>>
>>> HOWEVER, as of now, the switch doesn't sync when connected.  This
>>> appears
>>> to be a layer 2 issue, not a layer 3 issue.  My devices don't get an IP
>>> address from my local router.
>>>
>>> If I connect the Uverse Box directly to the wall (without the switch),
>>> then the layer-2 syncs just fine.
>>>
>>> I admit I have not tried connecting just the smart TV.
>>>
>>> However, the switch will not sync to the router.  The link lights just
>>> flash but don't stay on.
>>>
>>> What I don't understand is why the uverse box will happily sync up on
>>> layer 2 ethernet where my switch wont?
>>>
>>> -derek
>>>
>>>
>>>
>>> On Tue, April 9, 2019 5:22 pm, Alan Hightower via Ale wrote:
>>>>
>>>> I'm sure Uverse isn't providing multiple routable (real) IPv4
>>>> addresses.
>>>>   So the router is likely NAT masquerading any downstream devices that
>>>> try to initiate an outbound connection to the rest of the world.  In
>>>> fact, it's very likely both your local router and an upstream network
>>>> router are both NAT masquerading as there isn't any reason to have
>>>> routable IPv4 addresses anywhere in AT&T customer infrastructure.
>>>>
>>>> So my guess is AT&T pushed a firmware update to the router to change
>>>> the
>>>> masquerade policy.  Why?  Because they are AT&T of course.
>>>>
>>>> If your SLA covers providing you with general Internet service via the
>>>> wired router path, take it up with AT&T and have patience.  If they
>>>> expect you to only get it via WiFi from the router, take it up with
>>>> AT&T
>>>> and prepare for failure.  Also if the later, you could turn a close
>>>> proximity wifi client connection into bridge wired ethernet with a
>>>> number of commodity devices.
>>>>
>>>> You can do some poking around and report back.  Plug a PC into the
>>>> switch and see if you get a DHCP lease from the router.  Report back
>>>> the
>>>> lease details if any.  And if you do get a lease, make sure you can
>>>> ping
>>>> the default route and perform a traceroute to a North Star such as
>>>> 8.8.8.8 and report back.
>>>>
>>>> -Alan
>>>>
>>>>
>>>> On 2019-04-09 15:15, Derek Atkins via Ale wrote:
>>>>> Hi,
>>>>>
>>>>> I'm temporarily living in an apartment while my house is being
>>>>> renovated, and we have AT&T Uverse here.  Uverse uses ethernet for the
>>>>> "remote" TV box, and until a week ago I had installed a switch to
>>>>> allow
>>>>> me to plug in both the uverse box and my smart tv (the wifi there is
>>>>> spotty).  See diagram:
>>>>>
>>>>> [router] - [wall] - [building wiring] - [wall] - [switch] - TV and
>>>>> Uverse
>>>>>
>>>>> I was gone for a week and when I came back the switch was no longer
>>>>> syncing to the router, so neither the TV nor Uverse were working.  At
>>>>> first I thought it was the switch that went bad (there was a power
>>>>> outage when I was gone), so I ordered a replacement.  However, the
>>>>> replacement switch also does not work.  What is strange is that if I
>>>>> plug the uverse box in directly to the wall it works fine.  Moreover,
>>>>> if
>>>>> I plug the switch directly into the router using a local patch cord it
>>>>> works there.  So the only time the switch fails is when it uses the
>>>>> building wiring.
>>>>>
>>>>> As I said before, I'm in an apartment so don't really have access to
>>>>> the
>>>>> building wiring.  I can ask the building management, but I suspect
>>>>> they
>>>>> will foist me off to AT&T.  And if I go to AT&T, I suspect they will
>>>>> say
>>>>> they don't support switches -- and will ignore me because their Uverse
>>>>> box works just fine.
>>>>>
>>>>> SO...  Any ideas where I go from here?  They are only using 4 wires (2
>>>>> pairs) for the in-wall wiring, but that should be fine even for my
>>>>> little netgear switch.  At least, it was until a week ago.  I don't
>>>>> understand why the Uverse box works but a switch wont.
>>>>>
>>>>> Any ideas?
>>>>>
>>>>> -derek
>>>> _______________________________________________
>>>> Ale mailing list
>>>> Ale at ale.org
>>>> https://mail.ale.org/mailman/listinfo/ale
>>>> See JOBS, ANNOUNCE and SCHOOLS lists at
>>>> http://mail.ale.org/mailman/listinfo
>>>>
>>>
>>>
>>
>> _______________________________________________
>> Ale mailing list
>> Ale at ale.org
>> https://mail.ale.org/mailman/listinfo/ale
>> See JOBS, ANNOUNCE and SCHOOLS lists at
>> http://mail.ale.org/mailman/listinfo
> 
> 
> 
> 