@d0ugmac1 

d0ugmac1 wrote

Hi,

 

I  currently have 3 x 225-Outdoors linking 3 sites, basically wired is site A, then site B, then site C.  Site B is midway between A and C.

 

I'd fully expected A to mesh to B to mesh to C, but the remote devices have chosen to both link directly to A..and I understand the performance reasons for doing so.

 

However, I'd like to see a threshold set for this sort of situation because of the following:

 in this scenario, A is to the left B is up top right and C is lower right (highlighted link)

 

Today that lower link has gone as low as 13/13 while the upper link has typically remained 650/650 due to some pretty wet weather.  Despite losing some performance at B and increasing latency at C, I think it would be better at some point for C to connect back through B to A...however this doesn't seem to be an option.  It would be nice to characterize link capacities and hop counts...and then perform some smart decisions on when to say V-shaped and when to go linear.  Here's what the backhaul radio utilization looks like:

 

...and I've had three disconnect/re-adopts today already.  A normal day is always sub 20% (link ~175M/175M) as the radio link is usually ~-80dBm...today it's -89dbm.

 

I know I will ultimately need to do something about the lower (C) link path if I can't fix it by directing/optimizing the mesh.  Hoping I could set thresholds on Mesh radio channel or Min throughput or whatever to force a reconfig of the Mesh.  Thoughts?

1. You can lower the TX power on your root AP so that your EAP at site C can connect to the Mesh node at site B. Choose Custom and put a small number to lower the coverage.

2. For the signal that you have, -80dBm is not considered as good signal. And, if you mesh, you are likely to get a slow speed.

(The picture below is for reference only)

3. Consider relocating and find the optimal distance for all 3 sites. Also, adjust the antenna angle.

Hi Hank,

The above would probably eventually force the issue, however, it could also lead to worse overall performance and instabiliity.  Please let me explain:

First some data points

- all APs are currently at max (23) power

- variability in the A-C path is -9dB in poor weather conditions (so -80 on a dry day -89 on a very rainy day)

- A-B link is 68-70 over same range

If I drop the power at A enough so that C is forced to connect to B, there's a chance that it may 'prefer' again in the (sunnier) future a direct path based on fluctuations in the radio link budget.  I will also decrease the quality of connection to B...so I could wind up in a situation where C is uplinking through a poorer B connection and even flapping between direct and 1-hop.

It would seem more intelligent to me to set a 'Low Link Quality' parameter for the mesh, ie if channel utilization exceeds 50% and link capacity is more than 30% lower than nominal (this would be more intuitive than say a hard figure like -83dB) for > 5min, switch better to quality radio link but with higher hop count (so increased latency, reduced throughput, extra load on the hop AP).  This could be done by the AP, but since we have the Omada controller, it's ideally suited to monitor the links and decide for the APs if one should re-route or not (for instance the prospective hop AP is also suffering a huge load). 

At a minimum though, being able to set a dB mesh link threshold to prefer a hop path over direct would work.

Hi, I agree 100% with cutting outdoor power not really being a good idea.  I am intending to do some relocating to try to optimize the links now that the snow is receding too.

My point though is that the controller is already involved in mesh link establishment, it states right in the Controller User guide that the controller must remain running to ensure that the mesh stay operational.  We can already get regular stats on the quality of the mesh links from the EAP225's 'Mesh' status which also provides link utilization data for the 5G band used for the Mesh.  My point is rather than making a 1-time decision on the mesh topology, that it continue to monitor the mesh/mesh endpoint performances and to make allowance for particularly bad weather events by permitting  a topology reconfiguration that prefers 'goodput' (often defined as useful throughput) over something stiff and mechanical like minimizing hop counts.  

In my case this decision is very easy as they both home back to the same wired node on the same frequency.

Now, as it turns out I have a considerable amount of practical design experience with enterprise mesh networks, particularly wrt optimizing the hop counts.  One could configure the network such that optional paths are treated like vpn "tunnels" with routing weights assigned....if one link's ("tunnel") performance drops below a threshold (in my case the A-C tunnel), then it 'fails' over to the other tunnel (A-B-C)...there not need to reconfigure radios, just forwarding tables.

What we have today is good...just trying to make tomorrow better :)

Hi I wanted summarize in a nutshell my 'feature request' for the SDN Controller.  You'll see below my simplified scenario, 3 EAP225's, leftmost is wired.  Issue is the rightmost AP has a link that fluctuates considerably in wet weather, to the point where I start to get missed heartbeats etc.  My ask is to be able to set at least 1 threshold:

1.  Minimum signal quality id dBm  (couild also be min link BW in Mbps)

Upon which the Meshed AP would choose another path with stronger signal links.  Additional settings, could be considered

2. Minimum signal quality to jump to.  (ie if we fell from 80-->87, then I only want to change the uplink if signal is >84 for instance.

3. Prefer link budget over hop count (ie quality of each link back to wired AP is more important than minimizing hops/latency

4. Some kind of hysteresis (ie wait for 2min exceeding threshold before changing, wait 15min before switch back once link recovers and maybe only do this at 3am)

Here's the diagram, nominally the blue and green links are active. 

If blue drops below -86dBm (the Threshold to SWitch, I would like the leftmost AP to hop via the central AP.