Chapter 39 Differentiated Services
specifies the average rate at which packets are admitted to the network. The PIR is greater than or equal to the CIR. CIR and PIR values are based on the guaranteed and maximum bandwidth respectively as negotiated between a service provider and client.
Two Rate Three Color Marker evaluates incoming packets and marks them with one of three colors which refer to packet loss priority levels. High packet loss priority level is referred to as red, medium is referred to as yellow and low is referred to as green. After TRTCM is configured and DiffServ is enabled the following actions are performed on the colored packets:
•Red (high loss priority level) packets are dropped.
•Yellow (medium loss priority level) packets are dropped if there is congestion on the network.
•Green (low loss priority level) packets are forwarded.
TRTCM operates in one of two modes:
39.2.1 TRTCM - Color-blind Mode
All packets are evaluated against the PIR. If a packet exceeds the PIR it is marked red. Otherwise it is evaluated against the CIR. If it exceeds the CIR then it is marked yellow. Finally, if it is below the CIR then it is marked green.
Figure 183 TRTCM -
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39.2.2 TRTCM - Color-aware Mode
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