contention slots, QoS in 5ms frames

I have been having a real problem as we put more customers on the PMP450.  We do a decent amount of VoIP (around 40-60 streams per AP now) and are seeing a lot of packet loss.  We are co-located with PMP320s so are using 5ms frames.  I have looked at the PMP450 contention slot white paper and know I need to use more contention slots.  One thing I have been wondering is if when using 5ms frames you actually have only half of the contention slots you would on 2.5ms frames? 

I may just need to add more contention slots period, I'm just not sure.  I have 7 now, but this didn't seem to make any difference from 3.  I see lots of overloads on all of the RF out interfaces, on the AP and CSMs.  However, since the frame utilization feature came out, I have been graphing that in 5 minute intervals and the max I see is 49.8%.  With that said I've had the PMP320s at 100% utilization and still had good VoIP performace.  I think the traffic is being classed properly, as all our CSMs are running 2 VCs and I see the high prioirty queue's numbers increment.

I guess mainly I was just curious if anyone else had any QoS issues, and perhaps these might be associated with using 5ms frames.

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did u ever figure out what this was?

I have been out for awhile and just saw your reply.  I haven't really been able to figure anything out.  I set all of our APs to 15 contention slots to make sure that wasn't the problem.  We're still seeing quite a bit of VOIP packet loss on the uplink side even though we have QoS setup correctly.  It really becomes a problem if the customer is using a high percentage of their upload rate they are provisioned at.  Still seeing some packets on the Overload CSM tab but it's not very many.

Do you use high priority channel in the SM? Do you do any form of DSCP or 802.11? We had to do some pretty extensive checking and make sure all of our links from customers devices to AP's to backhauls were all respecting and provisioned for high priority channel and set to look in the same place.


We use a high priority channel and use DSCP on all of our equipment.  However in looking into this some more this morning I noticed that we had a few SMs out there that did not have the correct settings under DiffServ so I think this may be part of the problem!  We use RADIUS to set the channel but for some reason on initial setup we didn't get DiiffServ changed on the SM.  We are going to reboot the changed SMs tonight and see if this helps.