Hi, We have a couple of ME3600X (24cx) providing MPLS-based L2 services to anywhere between 20 and 80 customers per chassis. For the last few weeks we've been chasing a packet loss issue with some of those customers. It looks like the issue is more likely to happen on interfaces with multiple service instances then those with just a few. In most extreme cases we have customers doing 700Mb/s on a single port with the default queue depth (~ 50KB) and not a single dropped packet one one hand and a bunch of <10Mb/s on another dropping packets all the time.
Initially we used the following QoS (per service instance): policy-map PM-CUST-DEFAULT-100M-OUT class class-default shape average 100000000 This was causing massive drops even for services that were only transmitting 5-15Mb/s. Since queue-depth couldn't be applied with just the default class, we ended up with something like this: policy-map PM-CUST-DEFAULT-100M-OUT class CM-DUMMY class class-default shape average 100000000 queue-limit 1536000 bytes (where CM-DUMMY matches non-existing qos-group). This made things significantly better, but I feel that the queue of 1.5MB per service is quite excessive (bearing in mind that the device has only 22MB in total for shared queues on 1G ports). I was told by the TAC engineer that the memory is allocated dynamically, so it's save to oversubscribe it. At this stage I'm still waiting to learn if its possible to monitor the utilisation of that RAM. But the other question still lingers - what do you use as the queue-limit? I know it's traffic-dependant but with only 3 profiles available there is not much room to move (we use one profile for the core-facing classes, this is the second one) and a fairly universal depth has to be used. On top of that we don't really know what our customers use the service for, so the visibility is very limited. So if you use the platform - what's your magic number? kind regards Pshem _______________________________________________ cisco-nsp mailing list cisco-nsp@puck.nether.net https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/