Cisco 4500M Software Manual page 380

Overview of QoS
Table 29-1 IP Precedence and DSCP Values
3-bit IP
Precedence
0
1
2
3
1. MSb = most significant bit
• Classification is the selection of traffic to be marked.
• Marking, according to RFC 2475, is the process of setting a Layer 3 DSCP value in a packet; in this
publication, the definition of marking is extended to include setting Layer 2 CoS values.
• Scheduling is the assignment of Layer 2 frames to a queue. QoS assigns frames to a queue based on
internal DSCP values as shown in
Policing is limiting bandwidth used by a flow of traffic. Policing can mark or drop traffic.
•
Software Configuration Guide—Release 12.2(25)EW
29-4
1
6 MSb of ToS 6-bit
DSCP
8 7 6 5 4 3
0 0 0 0 0 0 0
0 0 0 0 0 1 1
0 0 0 0 1 0 2
0 0 0 0 1 1 3
0 0 0 1 0 0 4
0 0 0 1 0 1 5
0 0 0 1 1 0 6
0 0 0 1 1 1 7
0 0 1 0 0 0 8
0 0 1 0 0 1 9
0 0 1 0 1 0 10
0 0 1 0 1 1 11
0 0 1 1 0 0 12
0 0 1 1 0 1 13
0 0 1 1 1 0 14
0 0 1 1 1 1 15
0 1 0 0 0 0 16
0 1 0 0 0 1 17
0 1 0 0 1 0 18
0 1 0 0 1 1 19
0 1 0 1 0 0 20
0 1 0 1 0 1 21
0 1 0 1 1 0 22
0 1 0 1 1 1 23
0 1 1 0 0 0 24
0 1 1 0 0 1 25
0 1 1 0 1 0 26
0 1 1 0 1 1 27
0 1 1 1 0 0 28
0 1 1 1 0 1 29
0 1 1 1 1 0 30
0 1 1 1 1 1 31
Internal DSCP Values, page
1
3-bit IP 6 MSb of ToS
Precedence
8 7 6 5 4 3
4 1 0 0 0 0
1 0 0 0 0
1 0 0 0 1
1 0 0 0 1
1 0 0 1 0
1 0 0 1 0
1 0 0 1 1
1 0 0 1 1
5 1 0 1 0 0
1 0 1 0 0
1 0 1 0 1
1 0 1 0 1
1 0 1 1 0
1 0 1 1 0
1 0 1 1 1
1 0 1 1 1
6 1 1 0 0 0
1 1 0 0 0
1 1 0 0 1
1 1 0 0 1
1 1 0 1 0
1 1 0 1 0
1 1 0 1 1
1 1 0 1 1
7 1 1 1 0 0
1 1 1 0 0
1 1 1 0 1
1 1 1 0 1
1 1 1 1 0
1 1 1 1 0
1 1 1 1 1
1 1 1 1 1
29-12.
Chapter 29 Configuring QoS
6-bit
DSCP
0 32
1 33
0 34
1 35
0 36
1 37
0 38
1 39
0 40
1 41
0 42
1 43
0 44
1 45
0 46
1 47
0 48
1 49
0 50
1 51
0 52
1 53
0 54
1 55
0 56
1 57
0 58
1 59
0 60
1 61
0 62
1 63
OL-6696-01