Correction! It should be 1/25th of 100meg = 4 meg. Thats really strange to have such a small limit.
Found this also: http://www.gossamer-threads.com/lists/cisco/nsp/113754 Regards Roger On Mon, Aug 17, 2009 at 4:27 PM, Roger Wiklund <co...@xy.org> wrote: > Hi > > Im a bit confused regarding 3560 egress QoS. > > This is the default setting on a 3560, only "mls qos" is enabled globally. > > FastEthernet0/4 > Egress Priority Queue : disabled > Shaped queue weights (absolute) : 25 0 0 0 > Shared queue weights : 25 25 25 25 > The port bandwidth limit : 100 (Operational Bandwidth:100.0) > The port is mapped to qset : 1 > So after reading the document, the 4 egress queues are configure with 25% > bandwith each. and they are in shared mode, which means that they have a > minimum of 25% but can also use more from the other queues if available. > > But then we have the shaped queue. 25 0 0 0. > This is from the documentation: > > In shaped mode, the egress queues are guaranteed a percentage of the > bandwidth, and they are rate-limited to that amount. Shaped traffic does not > use more than the allocated bandwidth even if the link is idle. Shaping > provides a more even flow of traffic over time and reduces the peaks and > valleys of bursty traffic. With shaping, the absolute value of each weight > is used to compute the bandwidth available for the queues. > > By default, weight1 is set to 25; weight2, weight3, and weight4 are set to > 0, and these queues are in shared mode. > > For weight1 weight2 weight3 weight4, enter the weights to control the > percentage of the port that is shaped. The inverse ratio (1/weight) controls > the shaping bandwidth for this queue. Separate each value with a space. The > range is 0 to 65535. > > If you configure a weight of 0, the corresponding queue operates in shared > mode. The weight specified with the srr-queue bandwidth shape command is > ignored, and the weights specified with the srr-queue bandwidth share > interface configuration command for a queue come into effect. When > configuring queues in the same queue-set for both shaping and sharing, make > sure that you configure the lowest number queue for shaping. > The shaped mode overrides the shared mode. > > Does this then mean that per default, the egress queue 1, handling COS > 5, EF etc, only has 25mbit on a fastethernet port. Everything above that > gets dropped. > > And also: > > Priority-queue out > > When you configure this command, the SRR weight and queue size ratios are > affected because there is one less queue participating in SRR. This means > that weight1 in the srr-queue bandwidth shape or the srr-queue bandwidth > share command is ignored (not used in the ratio calculation). > > And also, when enabling egress prio queue, that queue qets 100% of the > bandwith? That will starve all the other traffic. Im reading in the Cisco > QoS book where you can have strict prio + weighted round robin. But it looks > like thats not available on the 3560. > > Thanks > > /Roger > > > > > > > > > > > > > _______________________________________________ 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/