Hi Pshem and George, There are two ASICs in the system and each has the buffer of 22 MB. 2x10Gig are one ASIC and 24x1Gig are on the other ASIC so 10 Gig buffers are separate from 1 Gig buffer. You are experiencing microburst in your network and it happens due to speed mismatch between ingress and egress interface. Higher the speed mismatch, the probability of microburst happening is more. Microburst causes sudden burst traffic in traffic resulting in packet drops due to lack of buffers. I would recommend using queue-limit percent and you can use 100% since the configuration allows oversubrcription assuming not all queues are oversubscribed at the same time. You can refer to my following Cisco Live deck for more information, https://docs.google.com/viewer?a=v&pid=sites&srcid=ZGVmYXVsdGRvbWFpbnxtd2FyaXN8Z3g6NzI1MTc2YzdjNGI2YmQ1NA
Best Regards, [http://www.cisco.com/web/europe/images/email/signature/horizontal06.jpg] Waris Sagheer Technical Marketing Manager Service Provider Access Group (SPAG) [email protected]<mailto:[email protected]> Phone: +1 408 853 6682 Mobile: +1 408 835 1389 CCIE - 19901 <http://www.cisco.com/> This email may contain confidential and privileged material for the sole use of the intended recipient. Any review, use, distribution or disclosure by others is strictly prohibited. If you are not the intended recipient (or authorized to receive for the recipient), please contact the sender by reply email and delete all copies of this message. For corporate legal information go to:http://www.cisco.com/web/about/doing_business/legal/cri/index.html From: Pshem Kowalczyk <[email protected]<mailto:[email protected]>> Date: Tuesday, March 26, 2013 at 2:05 PM To: 'George Giannousopoulos' <[email protected]<mailto:[email protected]>> Cc: "[email protected]<mailto:[email protected]>" <[email protected]<mailto:[email protected]>> Subject: Re: [c-nsp] ME3600X - tunning the output queues Hi, We're running 15.3 already. We got the buffers to 2MB per service, but still see occasional tail drop. kind regards Pshem On 27 March 2013 02:26, George Giannousopoulos <[email protected]<mailto:[email protected]>> wrote: Hi Pshem, We have seen the same issue with the 3800x In our case we use the maximum allowed packet number queue-limit 2457 packets If I'm not mistaken, there are improvements coming to the default queue sizes with the 15.3 train George On Mon, Mar 25, 2013 at 4:25 AM, Pshem Kowalczyk <[email protected]<mailto:[email protected]>> wrote: 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 [email protected]<mailto:[email protected]> https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected]<mailto:[email protected]> https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/ _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
