ZyXEL Communications P-791R v3 - Automatic Priority Queue Assignment

Chapter 17 Quality of Service (QoS)
P-79X Series User’s Guide
177
The DSCP value determines the forwarding behavior, the PHB (Per-Hop Behavior), that each packet
gets across the DiffServ network. Based on the marking rule, different kinds of traffic can be
marked for different kinds of forwarding. Resources can then be allocated according to the DSCP
values and the configured policies.
17.4.4 Automatic Priority Queue Assignment
If you enable QoS on the P-79X, the P-79X can automatically base on the IEEE 802.1p priority
level, IP precedence and/or packet length to assign priority to traffic which does not match a class.
The following table shows you the internal layer-2 and layer-3 QoS mapping on the P-79X. On the
P-79X, traffic assigned to higher priority queues gets through faster while traffic in lower index
queues is dropped if the network is congested.
Table 71 Internal Layer2 and Layer3 QoS Mapping
PRIORITY
QUEUE
LAYER 2 LAYER 3
IEEE 802.1P USER
PRIORITY
(ETHERNET
PRIORITY)
TOS (IP
PRECEDENCE)
DSCP
IP PACKET
LENGTH (BYTE)
0 1 0 000000
12
2 0 0 000000 >1100
3 3 1 001110
001100
001010
001000
250~1100
4 4 2 010110
010100
010010
010000
5 5 3 011110
011100
011010
011000
<250
6 6 4 100110
100100
100010
100000
5 101110
101000
7 7 6 110000
111000
7