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Do I mis-understand mesh?

cjust
Community Member

I'm curious if I don't have a proper understanding of what 'mesh' means.

We have a 3 story house with only a handful of rooms that are connected with cat-6 cable.  Our Internet connection enters the house in the basement.  In that basement location, I have my primary nest wifi router hooked up.  The 'out' signal on the primary router is hooked to a bridge that goes to a handful of rooms on the main and 2nd floor.  On the main floor, I've connected a 2nd nest wifi point into an ethernet jack that is attached to the bridge.  When I do a mesh test - that point registers as a 'strong signal' - which would be expected since it is wired into the main router.  However, I have some poor signal locations on the main floor, so I've set up another point that is only connected via wifi.  No matter where I put this point on the main floor, I get a 'weak signal'.  Even if I place it next to the wired point.  The only way to get a 'strong signal' is to hook it up downstairs next to the main router.   This obviously defeats the purpose of having the extra points.  I would expect the 2nd hard-wired point on the main floor to pass the signal along to the 3rd wifi point.  So - do I have a mis-understanding of how things should be working?

One more thing.. my access points aren't really true access points.  I bought two 2-packs from Amazon that were both routers - not a router and access point.

Thanks for any help!

15 REPLIES 15

MichaelP
Platinum Product Expert
Platinum Product Expert

Hello @cjust 

The 802.11s mesh interconnect between the access points (and the primary) runs over WiFi only. So, when you connect one access point (your second Nest WiFi Router unit) back to the primary via Ethernet, it has to stop talking to the mesh in order to avoid a traffic loop (since there are now two paths between the primary and that secondary). So, any wired secondary can't carry mesh traffic for more distant wireless-only / mesh secondaries. I hope that helps explain the behavior you're seeing.

In addition, the mesh path selection algorithm selects the path with the fewest hops through the mesh. So, even without any wired secondaries, if a distant mesh secondary can get through to the primary at all, it will skip any other intermediate mesh secondaries. In general, this is optimal, since there's only one 5GHz radio (and therefore only one 5GHz channel), and extra hops just mean retransmitting the same data back out on the same channel again. This is why the optimal placement advice is to put the primary as close to the center of your home as possible with mesh secondaries one or two rooms away from the primary – close enough they can get a strong 5GHz connection to it. From there, they will provide 2.4GHz and 5GHz coverage to more distant clients. Wired secondaries can be placed just about anywhere – even in outbuildings.

cjust
Community Member

Thanks for the reply!!  Your explanation makes sense... but I still think it defeats the purpose.  I would love to have my main router near the middle of the house... but my data enters in a far corner of my basement.  It seems odd to me that my wireless access point has to try to talk all the way to the main router when there is a wired access point right next to it.  Honestly, I had a better overall connection with the Fios router that came with my system.  The only reason I went with the Google mesh system was to try to extend out to some edge locations.  But if every edge location needs to connect all the way to my remote basement... then that doesn't do me much good.

In other words... it seems to me that I would want to have as many access points as I can that are on the wired back-bone... but every access point I put on the wired backbone stops being part of the 'mesh'.

 

You're saying it works like:

router<--------------wired---------------------->point

|<--------------------wireless--------------------------------------------------------------------------------------------->point

It would make more sense (and I thought it was) to be like:

router<-----------------wired------------------->point

                                                                            |<------------------------wireless----------------------->point

I guess you helped with what I suspected... I didn't understand how the mesh system worked.  

MichaelP
Platinum Product Expert
Platinum Product Expert

The mesh protocol doesn't run over Ethernet. So, a wired point can't extend the mesh without introducing a traffic loop. I know it "seems" like that should work. But, it doesn't – not with the constraints of the technology they are starting with. Get your primary as close to the center of your home as possible, as olavrb suggests – that will be a big win for performance.

cjust
Community Member

I guess I just don't understand the loop... 

how is:

router<----------wired------------>point<------------>wireless<---------------->point

different than

router<----------wireless------------>point<------------>wireless<---------------->point

Either way it is the middle point communicating back and forth with the router (middleman).  Is is common knowledge that if you want your points to act as a mesh they can't be part of a wired backbone?  I thought the goal was to get as many points wired as possible.

MichaelP
Platinum Product Expert
Platinum Product Expert

The loop is between the router and the first point, because you have both the wired and wireless paths up and running at the same time. So, before you can even think about that more distant wireless point, you have to see what the topology looks like for just the first point.

            <----wired------->

router                              point

            <----wireless---->

So, any broadcast packet will loop back and forth between the router and point endlessly. So, the spanning tree protocol is used to disconnect the wired point from the wireless mesh (almost) entirely. That breaks the loop, but it also means it can't talk to a more distant wireless-only point (so it can't carry that point's traffic).

Is this common knowledge? Hard to say. I've probably answered this specific question at least 100 times between this and the previous iteration of the Google community and Reddit over the last few years. That doesn't mean it's common knowledge, though – it's complicated, maybe even esoteric. I know how it works because I've been a computer engineer for 30+ years and I've dug through the low-level networking setup inside these devices. I don't expect most people to understand it at that level of detail. But, that's why I try to help people understand it to the degree they can.

Jeff
Community Specialist
Community Specialist

Hey, @dbainoflsmo.

Thanks for posting your question. When dealing with wired vs. wireless connections, that's sometimes a preference thing, but it is also very much something you can decide based on performance. If you do choose to go with wired, you just have to make sure you're following the recommended setup. Wireless works great if you can have a good connection to each of your points, however. I'm sharing an article that talks about hardwired devices on your setup, found here: https://bit.ly/3AkSkxQ

If you have any other questions, just let me know.

Thanks.

Jeff
Community Specialist
Community Specialist

Hi,
I just wanted to check in real fast to see if you still needed any help on this. If you're still needing assistance, please just let me know and I'll be happy to continue helping.
Thanks.

dbainoflsmo
Community Member

Thanks for your help, and especially for the link for more info.  I've got my primary router/node in the basement, connected to the fiber jack.  2nd node is on the 1st floor, connected wirelessly.  Set up is working fine, and we have adequate coverage on 2nd floor.  No issues, so I'm not going to change anything.  Thanks again for the info!

Jeff
Community Specialist
Community Specialist

Hey, dbainoflsmo.

Thanks for the follow up and letting us know things are working well for you and how you have your setup running. That will definitely help others out. I'm glad you're all sorted out.

Thanks.

Jeff
Community Specialist
Community Specialist

Hi, everyone.
As we haven't had any activity here recently I'm going to go ahead and close the thread. If you have more to add, feel free to start a new discussion.
Thanks

olavrb
Silver Product Expert
Silver Product Expert

You could consider ethernet over power line (HomePlug) or coax (MoCA) to that third puck.

Or make your current 2nd wired access point your primary, will give better wireless signal to that wireless node, but will require one more ethernet cable going down to the basement point.

Ashepherdson
Gold Product Expert
Gold Product Expert

So this is a common misconception that the points will look for the closest strong signal, they will actually always prefer the shortest path to the main router, even if it means a weak signal.  

My suggestion would be to have your main router in the centre(Sorry Canadian Spelling here) of your house, with the points spread out from there.  Either that, or be sure that the points are far enough away from the main router so that they cannot "see" it.  

olavrb
Silver Product Expert
Silver Product Expert

"Either that, or be sure that the points are far enough away from the main router so that they cannot "see" it."

802.11s does not travel over ethernet, and if wired backhaul is available, points wired to primary won't communicate wirelessly. At least not with Google Nest Wifi. Thus, your suggestion here won't work, 2nd point will not provide 802.11 mesh for the 3rd point. At least that's how I've understood it.

MichaelP
Platinum Product Expert
Platinum Product Expert

Eh, that is true for practical purposes under most conditions. But, under the covers, there's even more subtle behavior going on. When you wire a secondary, the (virtual) bridge that mesh interface and Ethernet interface are both connected to will disable forwarding through the mesh interface. So, yes, it can't carry mesh traffic back through Ethernet. But, the mesh interface isn't actually "down". So, in theory, it can still be an intermediate for a (very) distant mesh secondary – it's just that it will be sending that traffic on only over it's mesh link, not over Ethernet! It's counterintuitive, but I know people have built working systems that only worked because of this behavior (of course, it performs quite poorly, because multi-hop topologies only make sense in limited conditions that include obstructions). Sorry for being pedantic, though – I do agree that the advice to attempt to build a multi-hop topology is not recommended.

dbainoflsmo
Community Member

I'm getting ready to convert from Google TV to Google Mesh network.  The primary mesh device will be next to fiber jack, which is under basement stairs near center of house.  I will be connecting an ethernet switch to service wired network devices throughout the house.  2nd mesh device will be located near center of 2nd floor, I guess.  Question - should I connect 2nd mesh device over wireless, or plug it into wired ethernet?