Wireless Access

Contributor I

Mesh Link Parameters and Values

Is there any documentation that describes in detail the values for Mesh link Parameters and Values?  All I can find is a short sentence for things like Link Cost, but nothing for all Parameters/Values, and what the ranges are for the Values.


A client sent me screen shots from their Monitoring tab asking about Value ranges for pretty much every Parameter, and I don't know where to find an answer.  I don't see it in the Code guide or the VRD.


For example: Link Quality and TX/RX Rates aren't explained very well.  Is TX/RX simply a measurement of what is currently happening, or a general value of what the TX/RX rates should be on that link?  Link Quality is calculated how?




Valued Contributor II

Re: Mesh Link Parameters and Values



Are you looking for something on Mesh path selection parameters ??

Venu Puduchery,
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Contributor I

Re: Mesh Link Parameters and Values

I'm looking for any documentation that de-mystifies some of the Mesh Link Parameter Values.  Most of them are self explanatory.  Some could use some additional details.  From the web GUI Monitoring page:

Controller > Mesh Nodes > Topology

Name                                                          Self Explanatory

AP Type                                                      Self Explanatory

IP Address                                                  Self Explanatory

AP Group                                                    Self Explanatory

Cluster Name                                              Self Explanatory

Band/Channel/EIRP/MaxEIRP                    Self Explanatory

Path Cost  ---  This is some algorhythmic solution based upon Node Cost/Link Cost/etc.  What are acceptable Values here?  (ie Great = x to y, Good = a to b, Poor = c to d)?

Node Cost  ---  This is just more children equates to higher Node cost?  (Predictive Value: More Children = More traffic = Higher Node Cost?)

Link Cost   ---  Is this just (RSSI - Any AP cost Penalty) so the Value range should be anything > -25 dBm?  If so, why is this value "0" listed on the output of the Monitoring page?

Hop Count                                                  Self Explanatory

Link Quality   ---   What determines this Value, and what are acceptable Values here (ie Great = x to y, Good = a to b, Poor = c to d)?

Enet Ports                                                  Self Explanatory

Mesh Role                                                 Self Explanatory

No. of Children                                          Self Explanatory

Parent                                                        Self Explanatory

TX/RX   ---  Is this a current snapshot of TX/RX rates currently on this link, or an average/estimate of available bandwidth on this link at all times?

Last Update                                               Self Explanatory

Uptime                                                       Self Explanatory

Re: Mesh Link Parameters and Values

Sorry, just looking back at older threads...


Path Cost: Number of hops (basically), lower is better

Node Cost: Number of children, lower is better

Link Cost: Relative quality of the link, the more congested the higher the cost

Link Quality: RSSI value, higher is better to a limit (RSSI up to 35-40 is good, higher than that and you can over-drive the radios and kill performance, usually seen when setting up very short links or lab testing in a single room). 

TX/RX: From this output it's the Tx/Rx as seen at the last update, it is NOT real time, and usually reports the last seen Tx/Rx rates when the update occurred. To get real-time values, you would want to get into the CLI and run different sets of commands.


From the above, based on the controller config (reselection mode as well as metric algorithm settings), the mesh devices will take a path using the metrics above. You could have one poor RSSI link but is a single hop with no node or path costs that would be a better option than a link-path that has multiple nodes and paths (resulting in a higher overall path cost). 


For a mesh point, the total path cost is the sum of the parent path cost + node cost + link cost. 


Hope that helps. Unfortunately there is no valid way to put recommended values there as there's no valid way to quantify the many outdoor installations. Longer link mesh deployments will have numbers that are skewed as a factor of distance and FSPL, versus maybe shorter link urban deployments where distances are shorter, but more interference raises link cost. High bandwidth mesh deployments will have different values than mesh deployments with low bandwidth applications. 


The Outdoor 11n MIMO VRD has some great information in it regarding quantifying outdoor mesh deployments if you need more information.

Jerrod Howard
Distinguished Technologist, TME
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