Supporting Ethernet 802.1D Class of Service
IEEE 802.1Q is the most current Ethernet standard for Class of Service (CoS). It superseded an earlier standard, 802.1D, in 2005. IEEE 802.1Q slightly changed the ordering of the classes of service from its predecessor IEEE 802.1D for CoS 2 and CoS 0:
| CoS 802.1Q | CoS 802.1D |
|---|---|
| 7 Network Control | 7 Network Control |
| 6 Internetwork Control | 6 Voice (<10ms latency) |
| 5的声音(< 10 ms latency) | 5 Video (<100ms latency) |
| 4 Video (<100ms latency) | 4控制负载 |
| 3 Critical Applications | 3 Excellent Effort |
| 2良好的努力 | 0 Best Effort |
| 0 Best Effort | 2 Spare |
| 1 Background | 1 Background |
In 802.1D, both CoS 2 and CoS 1 are below CoS 0 (Best Effort).
When a switch is installed in a network of devices following 802.1D Class of Service, the QoS Cos map must be re-configured to follow the 802.1D standard by swapping the assignments of CoS 0 and 2:
switch#configswitch(config)#qos cos-map 0 local-priority 2 color green name Best_Effortswitch(config)#qos cos-map 2 local-priority 1 color green name Spareswitch(config)#exitswitch#show qos cos-mapcode_point local_priority color name ---------- -------------- ------- ---- 0 2 green Best_Effort 1 0 green Background 2 1 green Spare 3 3 green Critical_Applications 4 4 green Video 5 5 green Voice 6 6 green Internetwork_Control 7 7 green Network_Control