Table of Contents
Advertisement
Model 2160 Series Getting Started Guide
Bit 0
Bit 1
Bit 2
1
1
1
1
1
0
1
0
0
1
0
1
0
0
0
0
Bit 3
Bit 4
Bit 5
0
–
1
–
–
0
–
1
–
–
–
–
The standardized DiffServ field of the packet is marked with a value so that the packet receives a particular for-
warding treatment at each network node. RFC 2597 defines the assured forwarding (AF) classes. There are
four AF classes, AF1x through AF4x. Within each class, there are three drop probabilities. Depending on a
given network's policy, packets can be selected for a PHB based on required throughput, delay, jitter, loss, or
according to priority of access to network services. Classes 1 through 4 are referred to as AF classes.
Table 12
illustrates the DSCP coding for specifying the AF class with the probability. Bits 0, 1, and 2 define
the class; bits 3 and 4 specify the drop probability; bit 5 is always 0.
Medium Drop
Advanced Configuration Options
Table 11. Bits in the DSCP field
Precedence
1
7
Stays the same (link layer and routing protocol keep alive)
0
6
1
5
0
4
1
3
0
2
1
1
0
0
Usage
–
Delay
–
Delay
–
Throughput
–
Throughput
0
Reliability
1
Reliability
Table 12. DSCP Coding
Class 1
Low Drop
001010
AF11
DSCP 10
001100
AF12
DSCP 12
High Drop
001110
AF13
DSCP 14
Usage
Stays the same(used for IP routing Protocols)
Express Forwarding (EF)
Class 4
Class 3
Class 2
Class 1
Best effort
Meaning
Normal
Low
Normal
High
Normal
High
Class 2
Class 3
010010
011010
AF21
AF31
DSCP 18
DSCP 26
010100
011100
AF22
AF32
DSCP 20
DSCP 28
010110
011110
AF23
AF33
DSCP 22
DSCP 30
4 • Web configuration
Class 4
100010
AF41
DSCP 34
100100
AF42
DSCP 36
100110
AF43
DSCP 38
54
Advertisement
Table of Contents
