Dual-rate QoS defines two rates for traffic that is subject to QoS. The lower of the two rates is the CIR, which establishes a reserved traffic rate. The higher of the two rates is the peak rate, which establishes an upper limit for traffic. Dual-rate QoS is well suited to bursty traffic patterns which are common with typical data traffic. Dual-rate QoS is widely used in legacy Frame Relay and ATM leased lines.
NoteYou must configure the peak rate higher than the committed rate.
A three-color system is used with dual-rate QoS. As with single-rate QoS, traffic at or below the CIR is considered in-profile, marked green, and forwarded. The traffic that is above the CIR and below the PIR is out-of-profile and marked yellow. Traffic above the PIR is also out-of-profile and marked red. When incoming traffic is already marked yellow and is out of profile, it is marked red. Different switch platforms take different actions on the traffic marked yellow or red.