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What happens if I string an Ethernet cable between my stereo-paired PLAY:1s?


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I have a pair of PLAY:1s in a stereo pair. Both connect to SonosNet via a BOOST. What happens if I directly connect the two speakers with an Ethernet cable? Will one of the speakers receive its communication over the wire, while the other talks to the BOOST wirelessly?

Just curious, not trying to solve any problem I'm experiencing.
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Best answer by ratty 9 June 2017, 22:26

In many circumstances the wire between the pair will be used, with the player nearer to the BOOST making the wireless connection on behalf of both of them. For a simple pair (no grouping) this actually reduces wireless bandwidth demand by a factor of 3. Without the wire the stream would have to go BOOST->Left then Left->BOOST->Right.

I say 'in many circumstances' because there is a situation where the wire is ignored. This is where the STP root path costs for the two units in the pair differ by less than 10. The simplest way to check whether the wire is in use is to look at the Network Matrix at http://x.x.x.x:1400/support/review.

(The wire can be forced into use, in all cases, by disabling the radio on one of the pair. However this is an unsupported configuration.)

Note that in 'Standard Setup' the wire is useless as the Ethernet ports are disabled.
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I don't know the answer. If I had to guess, I wouldn't expect it to work that way.

I have a question for you though. Does this thought experiment have a practical application? It seems like pretty well every situation in which one can reach wireless and the second via a wired cable; the second is still going to be in range.

Your curiosity made me curious. 😃
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This is pretty much 100% curiosity, but a half-baked motivation is that if one of the speakers was communicating with the other over wired, that would be one fewer speaker soaking up WiFi bandwidth. I'll try it at some point. It will be interesting to see what the SonosNet mesh protocol makes of this configuration.
In many circumstances the wire between the pair will be used, with the player nearer to the BOOST making the wireless connection on behalf of both of them. For a simple pair (no grouping) this actually reduces wireless bandwidth demand by a factor of 3. Without the wire the stream would have to go BOOST->Left then Left->BOOST->Right.

I say 'in many circumstances' because there is a situation where the wire is ignored. This is where the STP root path costs for the two units in the pair differ by less than 10. The simplest way to check whether the wire is in use is to look at the Network Matrix at http://x.x.x.x:1400/support/review.

(The wire can be forced into use, in all cases, by disabling the radio on one of the pair. However this is an unsupported configuration.)

Note that in 'Standard Setup' the wire is useless as the Ethernet ports are disabled.
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That's very informative, @ratty -- thanks. I'll try it and see if the matrix adjusts.
Sonos is such fun.
The advice to run an Ethernet cable between a stereo pair has been offered over the years to users having trouble with dropouts from one channel, often from the right one. It can be a useful remedy, particularly where one or other speaker is used for a Line-In connection.
I ran one between my pair for some time and one speaker always used it; but things work just as well without it, and one wire less aids the aesthetic, so it's gone.
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I've now tried this, and can report that one of the PLAY:1s switches to being a tertiary node, indicating it's now communicating with the other over the wired connection. Nice.

I'm going to leave it this way, because the short cable run is easy and discreet. Thanks again for the responses!
Tertiary doesn't signify a wired connection per se. It merely means that the node isn't talking directly to the root bridge.
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Understood, but given it changed from Secondary to Tertiary after the introduction of the wire, that's the only plausible explanation, isn't it?

(I have one other Tertiary speaker, but that's connected over wireless, so I do understand that it doesn't just equate to 'wired'.)
Indeed. It's the most likely reason.

Go to http://x.x.x.x:1400/status/showstp on the device and look at the root port number. Then check which port has that number in brackets. It'll probably be the ethernet port, e.g.
code:
root port		   1	
...
eth0 (1) ...
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Thanks! Confirmed -- it is using the Ethernet port.

What is the signal strength you see for their cross communication in the matrix? That should be the new benchmark for 100% strength - it used to be 63, but has now been reset to be more than 70, but exactly what that is, is something you can see.
the new benchmark for 100% strength - it used to be 63, but has now been reset to be more than 70
I suspect it now goes to 99. I've seen 96, with a BOOST literally parked on top of a P:1. (I should note that the P:1's RF receiver was then overwhelmed by the BOOST's transmissions.)
In which case, the scale has also been changed and here is why I think so:
In the past my wired 1 pair showed 63, while a Connect Amp in line of sight of boost, about 12 feet away, showed 60/61. Now this amp shows 71, which is much further away from max than it used to be in the past if max is 99 as you say.
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What is the signal strength you see for their cross communication in the matrix? That should be the new benchmark for 100% strength - it used to be 63, but has now been reset to be more than 70, but exactly what that is, is something you can see.

Below is a representative signal matrix for my system. The 'Bedroom (L)' speaker is now connected to the 'Bedroom (R)' speaker via an Ethernet cable. (Of the remaining equipment, the 'BOOST', 'Front Reception' and 'Kitchen (L)' units are wired, the last one including a powerline hop in its network path.)

All quite compact then, with units pretty close together. Signal strengths are very good.

Below is a representative signal matrix for my system. The 'Bedroom (L)' speaker is now connected to the 'Bedroom (R)' speaker via an Ethernet cable.

Why then does the wired connection between the two show a signal strength of 59/61 and not the maximum possible?
Why then does the wired connection between the two show a signal strength of 59/61 and not the maximum possible?
Because that's the wireless signal strength (of a path which STP has blocked). Wired connections don't feature in the matrix. They can usually be inferred.
I don't understand and here is why:

When my play 1 pair that has speakers located less than 3 feet away from each other, but in the other room over from Boost, are not connected to each other by wire, they both prefer to stay connected from Boost, with signal strength in the mid 30s. Although the signal strength between the two is as high as 70/69, they prefer to not use that.

But as soon as they are wire connected to each other, one drops to tertiary mode, visibly using the connection from the other shown via the presence of green in their intersection box, that shows a drop to 63/67 from before. And does this, although the strength back the router remains the same as before.

A minor curiosity, I agree.
Signal strengths can and do vary for all kinds of reasons. The difference from 70/69 to 63/67 could simply be accounted for by the change in local conditions: the presence of the wire, the fact that the PLAY:1s Ethernet controllers are active, etc. etc.
The difference from 70/69 to 63/67 could simply be accounted for by the change in local conditions: the presence of the wire, the fact that the PLAY:1s Ethernet controllers are active, etc. etc.
Yes, but why would the two remain in secondary mode with mid thirties yellow boxes with a 70/69 wireless signal between the two, but start using the 63/67 strength wireless connection by dropping to tertiary mode as soon as a wire is introduced? Introducing the wire gets one to prefer to wirelessly connect to the other, while the absence of the wire leaves both in direct communication with the Boost. So the wire appears to be making a difference in their behaviour without itself being used for signal transfer.
Something doesn't add up. With the wire in place -- and a 'tertiary' label -- the wireless path should be blocked. You should see no coloured squares in the relevant matrix cells.

STP will strive to minimise the aggregate 'cost' of the path back to the root bridge.

When your two units were unwired, signal strengths to the BOOST in the mid 30s were perfectly viable, so each unit made a wireless connection thereto.

When you wire two units together the 'cost' of the Ethernet link is 10. This means that the wireless STP root path costs of the paired units -- which are a function of signal conditions -- have to differ by at least 10 for the wire to be 'cheaper' for one of the units than to use its direct wireless path. Assuming that's the case, the wire will come into use and said unit will become 'tertiary'. Its root path cost will become that of its twin plus 10.
With the wire in place -- and a 'tertiary' label -- the wireless path should be blocked. You should see no coloured squares in the relevant matrix cells.

Although I hate the phrase, all I can think of is: My bad.

Going back and forth between the two, I was confused and erred in saying that the wired connection has a coloured square; I added a wire again as soon as I read the above, and you are right - no coloured squares.

So, the tertiary mode is working via use of the wire, and one cannot see the signal strength it delivers, in the matrix.

But since both units work fine without it, the wire goes back into storage to reduce clutter.
So, the tertiary mode is working via use of the wire, and one cannot see the signal strength it delivers, in the matrix.
'Signal strength'? It's wired!!! It will be delivering 100Mbps.
Yes, but the question was in the context of what that is if it was used as a marker for how good the signal strength is if the matrix says it is 70 as an example, for a wireless signal. Is that 70% as good as that
from a wired connection? Or am I doing apples v oranges?