Wireless Access


Low RRSI and High Latency on Mesh Links

I am in the process of implementing a new wirelesss deployment combining Indoor Client access APs (AP 320 Series) with AP 277s providing both Mesh connectivity and Client access outdoors.  There are termainated to a pair of 7205 controllers in a Master/Local Redundancy group.


The indoor deployment and the Outdoor Client APs are working very well, but the Mesh links have become a major problem.


There are currently 2 seperate sets of Mesh Portal/Point connections.  Once set is point to point between 2 AP 277s (1 Portal and 1 Point) seperated by ~350 ft with direct line of sight with the Portal AP mounted ~20-25 ft higher than the Point AP.


The other Mesh connection is a set of 3 AP 277s connecting over a distance of close to 1000 ft. mounted at the same height, again with direct line of site between the Portal and Points.


The mesh links are replacing old Cisco 1310 bridges and currently, I am seeing RSSI values in the 17 to 25 db range and 300-400 ms latency over the new links.  Actual throughput is close to -10X (ie. ten times worse)  over the new links as oposed to what was experienced woth the old equipment.


I orginally also had a problem where the Mesh Links would go hard down for 5 to 10 minutes at a time, but that has gone away since I set the the ARM profiles on the Mesh radios to arm-maintain.


A have attached the output from multiple "show ap mesh" commands and the current running confiugration of the Master Controller and can provide any other logs if required.


Any help or advice would be much appreciated.


MVP Expert

Re: Low RRSI and High Latency on Mesh Links

Do you have a map or can you make one that shows where these APs are, draw in their links, etc? I think RSSI mesh link values look WAY too low for a 277 link at 350ft. There is 100% clear line of sight, no trees, etc? Are these 277s aimed towards the ground (the radome pointed down) or are they facing in the direction of the mesh (AP-277 radome facing in the direction the mesh links should be)? 


Also, there is a distance parameter you would want to set on any links over 500 ft. Essentially you would need to enter a value (in meters) of the round trip distance. So for the 1000ft link, you would want to create and apply an a-radio profile with a distance value of approx 325m (rounding up to the nearest ?25). For the shorter links of 350ft, that is fine to leave as is). 


It sounds like something physical is causing the RSSI to be lower than it should (mis-alignment or physical attenuation/blockage). 


Also I would NOT post your config online here for anyone to view, you can PM it to relevant people, but otherwise I would modify your post and delete your config. The mesh config output htough is fine to leave up. 

Jerrod Howard
Distinguished Technologist, TME
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