On Fri, 2009-10-09 at 13:58 +0200, David Granzer wrote: > please could anybody explain the diffrence when 6500/7600 running with > MLS QoS enabled (mls qos) and when running with MLS QoS disabled "no > mls qos" ?
Here's a relatively compact and quite good explanation of 6500 QoS: http://www.cisco.com/en/US/prod/collateral/switches/ps5718/ps708/white_paper_c11_538840.html Remember that QoS is all about _degrading_ certain services for the benifit of other services. It will not raise the total "quality". Just enabling "mls qos" without doing anything else and without having a plan should be considered an error. When enabling QoS globally (via "mls qos") the switch will adjust certain parameters like drop thresholds and CoS-maps. Take a look at the output of "show queueing interface GiX/Y" from a configuration with and without "mls qos" to get some hints: Router#sh queueing int gi4/1 Interface GigabitEthernet4/1 queueing strategy: Weighted Round-Robin QoS is disabled globally Trust boundary disabled Trust state: trust DSCP Extend trust state: not trusted [COS = 0] Default COS is 0 Queueing Mode In Tx direction: mode-cos Transmit queues [type = 1p3q8t]: Queue Id Scheduling Num of thresholds ----------------------------------------- 01 WRR 08 02 WRR 08 03 WRR 08 04 Priority 01 WRR bandwidth ratios: 100[queue 1] 0[queue 2] 0[queue 3] queue-limit ratios: 100[queue 1] 0[queue 2] 0[queue 3] 0[Pri Queue] queue tail-drop-thresholds -------------------------- 1 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 2 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 3 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] queue random-detect-min-thresholds ---------------------------------- 1 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 2 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 3 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] queue random-detect-max-thresholds ---------------------------------- 1 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 2 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 3 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] WRED disabled queues: 1 2 3 queue thresh cos-map --------------------------------------- 1 1 0 1 2 3 4 5 6 7 1 2 1 3 1 4 1 5 1 6 1 7 1 8 2 1 2 2 2 3 2 4 2 5 2 6 2 7 2 8 3 1 3 2 3 3 3 4 3 5 3 6 3 7 3 8 4 1 Queueing Mode In Rx direction: mode-cos Receive queues [type = 1q8t]: Queue Id Scheduling Num of thresholds ----------------------------------------- 01 WRR 08 WRR bandwidth ratios: 100[queue 1] queue-limit ratios: 100[queue 1] queue tail-drop-thresholds -------------------------- 1 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] queue thresh cos-map --------------------------------------- 1 1 0 1 2 3 4 5 6 7 1 2 1 3 1 4 1 5 1 6 1 7 1 8 Packets dropped on Transmit: BPDU packets: 0 queue dropped [cos-map] --------------------------------------------- 1 0 [0 1 2 3 4 5 6 7 ] Packets dropped on Receive: BPDU packets: 0 queue dropped [cos-map] --------------------------------------------- 1 0 [0 1 2 3 4 5 6 7 ] Router# Router#conf t Enter configuration commands, one per line. End with CNTL/Z. Router(config)#mls qos Router(config)#^Z Router# Router#sh queuei int gi4/1 Interface GigabitEthernet4/1 queueing strategy: Weighted Round-Robin Port QoS is enabled Trust boundary disabled Trust state: trust DSCP Extend trust state: not trusted [COS = 0] Default COS is 0 Queueing Mode In Tx direction: mode-cos Transmit queues [type = 1p3q8t]: Queue Id Scheduling Num of thresholds ----------------------------------------- 01 WRR 08 02 WRR 08 03 WRR 08 04 Priority 01 WRR bandwidth ratios: 100[queue 1] 150[queue 2] 200[queue 3] queue-limit ratios: 50[queue 1] 20[queue 2] 15[queue 3] 15[Pri Queue] queue tail-drop-thresholds -------------------------- 1 70[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 2 70[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 3 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] queue random-detect-min-thresholds ---------------------------------- 1 40[1] 70[2] 70[3] 70[4] 70[5] 70[6] 70[7] 70[8] 2 40[1] 70[2] 70[3] 70[4] 70[5] 70[6] 70[7] 70[8] 3 70[1] 70[2] 70[3] 70[4] 70[5] 70[6] 70[7] 70[8] queue random-detect-max-thresholds ---------------------------------- 1 70[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 2 70[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] 3 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] WRED disabled queues: queue thresh cos-map --------------------------------------- 1 1 0 1 2 1 1 3 1 4 1 5 1 6 1 7 1 8 2 1 2 2 2 3 4 2 3 2 4 2 5 2 6 2 7 2 8 3 1 6 7 3 2 3 3 3 4 3 5 3 6 3 7 3 8 4 1 5 Queueing Mode In Rx direction: mode-cos Receive queues [type = 1q8t]: Queue Id Scheduling Num of thresholds ----------------------------------------- 01 WRR 08 WRR bandwidth ratios: 100[queue 1] queue-limit ratios: 100[queue 1] queue tail-drop-thresholds -------------------------- 1 100[1] 100[2] 100[3] 100[4] 100[5] 100[6] 100[7] 100[8] queue thresh cos-map --------------------------------------- 1 1 0 1 2 3 4 5 6 7 1 2 1 3 1 4 1 5 1 6 1 7 1 8 Packets dropped on Transmit: BPDU packets: 0 queue dropped [cos-map] --------------------------------------------- 1 0 [0 1 ] 2 0 [2 3 4 ] 3 1 [6 7 ] 4 0 [5 ] Packets dropped on Receive: BPDU packets: 0 queue dropped [cos-map] --------------------------------------------- 1 0 [0 1 2 3 4 5 6 7 ] Router# -- Peter _______________________________________________ cisco-nsp mailing list [email protected] https://puck.nether.net/mailman/listinfo/cisco-nsp archive at http://puck.nether.net/pipermail/cisco-nsp/
