Cisco WS-X6K-SUP1A-PFC= Software Guide - Page 732

Understanding How QoS Works Chapter 41 Configuring QoS 2q2t Ports 1p2q2t Ports 1p3q1t Ports For 2q2t ports, each transmit queue has two drop thresholds that function as follows: • Frames with CoS 0, 1, 2, or 3 go to the low-priority transmit queue (queue 1): - Using transmit queue 1, drop-threshold 1, the switch drops frames with CoS 0 or 1 when the low-priority transmit-queue buffer is 80 percent full. - Using transmit queue 1, drop threshold 2, the switch drops frames with CoS 2 or 3 when the low-priority transmit-queue buffer is 100 percent full. • Frames with CoS 4, 5, 6, or 7 go to the high-priority transmit queue (queue 2): - Using transmit queue 2, drop threshold 1, the switch drops frames with CoS 4 or 5 when the high-priority transmit-queue buffer is 80 percent full. - Using transmit queue 2, drop threshold 2, the switch drops frames with CoS 6 or 7 when the high-priority transmit-queue buffer is 100 percent full. For 1p2q2t ports, the low- and high-priority standard transmit queues each have two drop thresholds that function as follows: • Frames with CoS 0, 1, 2, or 3 go to the low-priority standard transmit queue (queue 1): - Using standard transmit queue 1, drop threshold 1, the switch drops frames with CoS 0 or 1 when the low-priority transmit-queue buffer is 80 percent full. - Using standard transmit queue 1, drop threshold 2, the switch drops frames with CoS 2 or 3 when the low-priority transmit-queue buffer is 100 percent full. • Frames with CoS 4, 6, or 7 go to the high-priority standard transmit queue (queue 2): - Using standard transmit queue 2, drop threshold 1, the switch drops frames with CoS 4 when the high-priority transmit-queue buffer is 80 percent full. - Using standard transmit queue 2, drop threshold 2, the switch drops frames with CoS 6 or 7 when the high-priority transmit-queue buffer is 100 percent full. • Frames with CoS 5 go to the strict-priority transmit queue (queue 3), where the switch drops frames only when the buffer is 100 percent full. For 1p3q1t ports, the queues each have one drop threshold that function as follows: • Frames with CoS 0 and 1 go to the low-priority standard transmit queue (queue 1). • Frames with CoS 2, 3, or 4 go to the medium-priority standard transmit queue (queue 2). 41-26 Catalyst 6000 Family Software Configuration Guide-Releases 6.3 and 6.4 78-13315-02