ADTRAN AOS Version R10.1.0 Command Reference Manual page 3309

Command Reference Guide
Assured Forwarding PHB
The flexibility of DiffServ allows for more developed subclasses of service within each main class using the
last three bits of the DSCP. As defined in RFC 2597, the assured forwarding PHB creates four main
classes of service:
The first three bits of the DSCP specify the class and the last bit is always zero. Each class is separated
into subclasses using the two remaining bits in the DSCP (bits 3 and 4). The subclasses are divided based
on the likelihood that packets in the class are dropped in the event of network congestion. The higher the
value for bits 3 and 4, the greater the likelihood that the packets will be dropped.
The following table lists the assured forwarding PHB subclasses and their corresponding DSCP bits and
values.
Class
AF1
AF2
AF3
AF4
60000CRG0-35E
Class DSCP Bits
AF1
AF2
AF3
AF4
X indicates a do not care value.
Bit 3 Bit 4
0 1
1 0
1 1
Subclass DSCP Bits
1 001010
2 001100
3 001110
1 010010
2 010100
3 010110
1 011010
2 011100
3 011110
1 100010
2 100100
3 100110
Copyright © 2012 ADTRAN, Inc.
001XX0
010XX0
011XX0
100XX0
Drop
Precedence
Low
Medium
High
DSCP Value
10
12
14
18
20
22
26
28
30
34
36
38
Route Map Command Set
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