Does the PA-A3-OC12 support per-virtual-channel (per-VC) CBWFQ and LLQ?
A. Cisco IOS Software Release 12.0S introduced support for distributed quality of service (QoS) on the PA-A3-OC12 (CSCdv67540 (registered customers only) ). CBWFQ is supported on the PA-A3-OC12 as of Cisco IOS Software Release 12.1(11b)E; and LLQ is supported on the PA-A3-OC12 as of Cisco IOS Software Release 12.1(12c)E1. With per-VC queuing, the ATM interface driver exerts backpressure when the layer-2 hardware queue (known as the transmit ring) is full. Excess packets then are stored in the layer-3 queuing system, where a QoS service policy applies. By default, a UBR VC is assigned a transmit ring limit (tx_limit) value of 128 particles. A VBR-nrt VC is assigned a tx_limit value based on the following formula: Average rate (SCR) × 2 × TOTAL_CREDITS / VISIBLE_BANDWIDTH TOTAL_CREDITS = 8192 VISIBLE_BANDWIDTH = 599040 If this formula calculates a tx_limit value which is less than the default of 128, then the tx_limit of the VC is set to 128. Alternately, you can use the tx-ring-limit co
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- Does the PA-A3-OC12 support per-virtual-channel (per-VC) CBWFQ and LLQ?
