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Understanding CoS Code-Point Aliases

A code-point alias assigns a name to a pattern of code-point bits. You can use this name instead of the bit pattern when you configure other CoS components such as classifiers, drop-profile maps, and rewrite rules.

Behavior aggregate classifiers use class-of-service (CoS) values such as Differentiated Services code points (DSCPs) and IEEE 802.1 bits to associate incoming packets with a particular CoS servicing level. You can assign a meaningful name or alias to the CoS values and use that alias instead of bits when configuring CoS components. These aliases are not part of the specifications but are well known through usage. For example, the alias for DSCP 101110 is widely accepted as ef (expedited forwarding).

When you configure classes and define classifiers, you can refer to the markers by alias names. You can configure alias names for user-defined classifiers. If the value of an alias changes, it alters the behavior of any classifier that references it.

You can configure code-point aliases for the following type of CoS markers:

  • dscp or dscp-ipv6—Handles incoming IP and IPv6 packets.
  • ieee-802.1—Handles Layer 2 CoS.

This topic covers:

Default Code-Point Aliases

Table 1 shows the default mapping of code-point aliases to IEEE code points.

Table 1: Default IEEE 802.1 Code-Point Aliases

CoS Value Types

Mapping

be

000

be1

001

ef

010

ef1

011

af11

100

af12

101

nc1

110

nc2

111

Table 2 shows the default mapping of code-point aliases to DSCP and DSCP IPv6 code points.

Table 2: Default DSCP and DSCP IPv6 Code-Point Aliases

CoS Value Types

Mapping

ef

101110

af11

001010

af12

001100

af13

001110

af21

010010

af22

010100

af23

010110

af31

011010

af32

011100

af33

011110

af41

100010

af42

100100

af43

100110

be

000000

cs1

001000

cs2

010000

cs3

011000

cs4

100000

cs5

101000

nc1

110000

nc2

111000

Published: 2014-07-23

Supported Platforms

Published: 2014-07-23