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 |
