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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.

Note:

This topic applies to all EX Series switches except the EX4600. Because the EX4600 uses a different chipset than other EX Series switches, the code-point aliases on EX4600 match those on QFX Series switches. For EX4600 code-point aliases, see Understanding CoS Code-Point Aliases.

Behavior aggregate classifiers use class-of-service (CoS) values such as Differentiated Services code points (DSCPs), IP precedence, and IEEE 802.1p bits to associate incoming packets with a particular CoS servicing level. On a switch, you can assign a meaningful name or alias to the CoS values and use this 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 user-defined classifiers in terms of alias names. If the value of an alias changes, it alters the behavior of any classifier that references it.

This topic covers:

Default Code-Point Aliases

Table 1 shows the default mappings between the bit values and standard aliases.

Table 1: Default Code-Point Aliases

CoS Value Types

Mapping

DSCP CoS Values

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/cs6

110000

nc2/cs7

111000

IEEE 802.1p CoS Values

be

000

be1

001

ef

100

ef1

101

af11

010

af12

011

nc1/cs6

110

nc2/cs7

111

Legacy IP Precedence CoS Values

be

000

be1

001

ef

010

ef1

011

af11

100

af12

101

nc1/cs6

110

nc2/cs7

111