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Chapter 14 Quality of Service (QoS)
Token Bucket is similar to tokens in a bucket to control when traffic can be
transmitted. The bucket is a buffer that temporarily stores outgoing packets and
transmits them at an average rate.
Single Rate Three Color Marker (SRTCM) and Two Rate Three Color Marker
(TRTCM) evaluate incoming packets and mark them with one of three colors which
refer to packet loss priority (PLP) levels. High PLP level is referred to as red,
medium is referred to as yellow and low is referred to as green. The difference
between the two meters is the types of parameters used to evaluate packets.
SRTCM uses committed information rate (CIR), the committed burst size and the
excess burst size. TRTCM uses peak information rate (PIR), CIR, peak burst size
and a committed burst size. After SRTCM and TRTCM are 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.
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P-794H User's Guide
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