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View Full Version : Auto-detection of full and half-duplex



Olav Sunde
2004-12-16, 14:31
I have just startet to use my wired Squeezebox - in very nice Triple
Platinum colour :>). Easy to set up and every thing is working as
expected so far. But looking at the log of my network switch, an HP
J4813A, I notice that the switch is negotiating half-duplex with the SB.
Also I see some collisions and quite a bit of deferred TX.
If I force the switch port to 10Mbps full-duplex the SB clearly does not
sense this and the switch reports excessive CRC and alignment errors and
various other stuff because of the duplex mismatch. I have checked
cables and connectors etc. and moved the SB to other ports with no
change. None of the other 12 active ports on the switch show any trouble.
The technical specification of the SB states "Auto-detection of full and
half-duplex modes" on the ethernet port, but this does not seem to be
correct.
Anyone else with experience/suggestions here?
Can I send a command to the SB via SlimServer or some other way to set
the ethernet port to full-duplex?

Thanks

Olav Sunde

David Brittain
2004-12-19, 08:16
I would be interested in the answer to this too. I have just moved to a
new switch, and am experiencing regular drop-outs. The switch shows the
connection to the squeezebox as being half-duplex. I am wondering if
this might be part of the problem.

Dave

Olav Sunde wrote:

> I have just startet to use my wired Squeezebox - in very nice Triple
> Platinum colour :>). Easy to set up and every thing is working as
> expected so far. But looking at the log of my network switch, an HP
> J4813A, I notice that the switch is negotiating half-duplex with the
> SB. Also I see some collisions and quite a bit of deferred TX.
> If I force the switch port to 10Mbps full-duplex the SB clearly does
> not sense this and the switch reports excessive CRC and alignment
> errors and various other stuff because of the duplex mismatch. I have
> checked cables and connectors etc. and moved the SB to other ports
> with no change. None of the other 12 active ports on the switch show
> any trouble.
> The technical specification of the SB states "Auto-detection of full
> and half-duplex modes" on the ethernet port, but this does not seem to
> be correct.
> Anyone else with experience/suggestions here?
> Can I send a command to the SB via SlimServer or some other way to set
> the ethernet port to full-duplex?
>
> Thanks
>
> Olav Sunde
>
>

Olav Sunde
2004-12-20, 13:13
Hello David and Christopher,
I agree that this may not be a problem in my setup as I use a network
switch that has an advanced management interface, but I have seen posts
on this board describing problems with wired SB's that I am certain can
be due to a duplex mismatch.
I'll send my request to support at Slimdevices to see what response I
get from them. I'll post here as soon as I get a response.

Olav

Christopher Jacob wrote:
> Perhaps my less than stellar grasp of networking will come into play here
> but... It doesn't seem to me that the squeezebox communicates up stream very
> often, so when it does have to send a packet or two the data stored in the
> buffer should compensate for the downstream blocking...
>
> Now on the other hand, it says its 10/100 full duplex so I guess it should
> perform as advertised. I just don't know if you are going to see any
> detectable performance increases.
>
> ~c
>
>
>>-----Original Message-----
>>From: discuss-bounces (AT) lists (DOT) slimdevices.com [mailto:discuss-
>>bounces (AT) lists (DOT) slimdevices.com] On Behalf Of David Brittain
>>Sent: Sunday, December 19, 2004 10:17 AM
>>To: Slim Devices Discussion
>>Subject: [slim] Auto-detection of full and half-duplex
>>
>>I would be interested in the answer to this too. I have just moved to a
>>new switch, and am experiencing regular drop-outs. The switch shows the
>>connection to the squeezebox as being half-duplex. I am wondering if
>>this might be part of the problem.
>>
>>Dave
>>
>>Olav Sunde wrote:
>>
>>
>>>I have just startet to use my wired Squeezebox - in very nice Triple
>>>Platinum colour :>). Easy to set up and every thing is working as
>>>expected so far. But looking at the log of my network switch, an HP
>>>J4813A, I notice that the switch is negotiating half-duplex with the
>>>SB. Also I see some collisions and quite a bit of deferred TX.
>>>If I force the switch port to 10Mbps full-duplex the SB clearly does
>>>not sense this and the switch reports excessive CRC and alignment
>>>errors and various other stuff because of the duplex mismatch. I have
>>>checked cables and connectors etc. and moved the SB to other ports
>>>with no change. None of the other 12 active ports on the switch show
>>>any trouble.
>>>The technical specification of the SB states "Auto-detection of full
>>>and half-duplex modes" on the ethernet port, but this does not seem to
>>>be correct.
>>>Anyone else with experience/suggestions here?
>>>Can I send a command to the SB via SlimServer or some other way to set
>>>the ethernet port to full-duplex?
>>>
>>>Thanks
>>>
>>>Olav Sunde
>>>
>>>

Olav Sunde
2004-12-22, 09:42
Hi,
this what I got as a first answer, not very promising...I replied to
this but have not yet received an answer so I'll keep trying.

* * *
21.12.2004, you wrote:
Greetings Olav,

The Squeezebox does have autodetection of full/half duplex transmission
modes. We suggest you try hooking a standard NetGear switch in between
to see if the problem persists.

Regards,
Rico
* * *

Olav

seanadams
2004-12-22, 10:36
Olav,

There are no known problems with our ethernet interface. That doesn't
mean you haven't found a problem, it just means that out of all the
thousands of squeezeboxen shipped, and over a year of real-world
testing, we've NEVER found a problem.

Full duplex definitely works, although the J4813A switch is not a
particular model that we've had any reports about before, one way or
another.

Again the best advice is to try putting a standard netgear/linksys box
in there and see if it works any better. The cheapest simplest switches
(perhaps ironically) are much less problematic in general than the more
advanced/configurable devices.

Also check you have CAT5 cables that are wired correctly. The wiring
should go:

Orange-white
Orange
Green-white
Blue
Blue-white
Green
Brown-white
Brown

Often you will find cables that were not constructed properly (eg with
green paired on pins 3&4 and blue paired on pins 5&6). This will cause
a tremendous amount of noise on the line, which manifests itself in
exactly the symptoms you've described.

Hope this helps.

Sean

On Dec 20, 2004, at 12:13 PM, Olav Sunde wrote:

> Hello David and Christopher,
> I agree that this may not be a problem in my setup as I use a network
> switch that has an advanced management interface, but I have seen
> posts on this board describing problems with wired SB's that I am
> certain can be due to a duplex mismatch.
> I'll send my request to support at Slimdevices to see what response I
> get from them. I'll post here as soon as I get a response.
>
> Olav
>
> Christopher Jacob wrote:
>> Perhaps my less than stellar grasp of networking will come into play
>> here
>> but... It doesn't seem to me that the squeezebox communicates up
>> stream very
>> often, so when it does have to send a packet or two the data stored
>> in the
>> buffer should compensate for the downstream blocking...
>> Now on the other hand, it says its 10/100 full duplex so I guess it
>> should
>> perform as advertised. I just don't know if you are going to see any
>> detectable performance increases.
>> ~c
>>> -----Original Message-----
>>> From: discuss-bounces (AT) lists (DOT) slimdevices.com [mailto:discuss-
>>> bounces (AT) lists (DOT) slimdevices.com] On Behalf Of David Brittain
>>> Sent: Sunday, December 19, 2004 10:17 AM
>>> To: Slim Devices Discussion
>>> Subject: [slim] Auto-detection of full and half-duplex
>>>
>>> I would be interested in the answer to this too. I have just moved
>>> to a
>>> new switch, and am experiencing regular drop-outs. The switch shows
>>> the
>>> connection to the squeezebox as being half-duplex. I am wondering if
>>> this might be part of the problem.
>>>
>>> Dave
>>>
>>> Olav Sunde wrote:
>>>
>>>
>>>> I have just startet to use my wired Squeezebox - in very nice Triple
>>>> Platinum colour :>). Easy to set up and every thing is working as
>>>> expected so far. But looking at the log of my network switch, an HP
>>>> J4813A, I notice that the switch is negotiating half-duplex with the
>>>> SB. Also I see some collisions and quite a bit of deferred TX.
>>>> If I force the switch port to 10Mbps full-duplex the SB clearly does
>>>> not sense this and the switch reports excessive CRC and alignment
>>>> errors and various other stuff because of the duplex mismatch. I
>>>> have
>>>> checked cables and connectors etc. and moved the SB to other ports
>>>> with no change. None of the other 12 active ports on the switch show
>>>> any trouble.
>>>> The technical specification of the SB states "Auto-detection of full
>>>> and half-duplex modes" on the ethernet port, but this does not seem
>>>> to
>>>> be correct.
>>>> Anyone else with experience/suggestions here?
>>>> Can I send a command to the SB via SlimServer or some other way to
>>>> set
>>>> the ethernet port to full-duplex?
>>>>
>>>> Thanks
>>>>
>>>> Olav Sunde
>>>>
>>>>

Olav Sunde
2004-12-22, 16:29
Sean, thanks for the reply. I'll try a Cisco switch and a few other
candidates to check. As to the cat5 cable - it is OK. I am responsible
for a large network with several thousand ethernet ports so I know all
about good and bad cables :>). This is why I spotted the problem in the
first place. I'll be streaming uncompressed wav to my SB so it would be
nice to avoid the trouble half-duplex can give. For streaming
compressed audio half-diplex would not be problem because of the low
bandwith demands. I'll post my findings when I've done some testing.

Olav