Automatic Priority Queue Assignment - ZyXEL Communications P-660HW-Tx v3 User Manual

Chapter 16 Quality of Service (QoS)
DSCP is backward compatible with the three precedence bits in the ToS octet so
that non-DiffServ compliant, ToS-enabled network device will not conflict with the
DSCP mapping.
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.

16.8.4 Automatic Priority Queue Assignment

If you enable QoS on the ZyXEL Device, the ZyXEL Device 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 ZyXEL Device. On the ZyXEL Device, traffic assigned to higher priority queues
gets through faster while traffic in lower index queues is dropped if the network is
congested.
Table 78 Internal Layer2 and Layer3 QoS Mapping
PRIORITY
QUEUE
0
1
2
3
4
272
DSCP (6 bits)
LAYER 2 LAYER 3
IEEE 802.1P
USER PRIORITY TOS (IP
(ETHERNET PRECEDENCE)
PRIORITY)
1 0
2
0 0
3 1
4 2
Unused (2 bits)
DSCP
000000
000000
001110
001100
001010
001000
010110
010100
010010
010000
P-660HW-Tx v3 User's Guide
IP PACKET
LENGTH (BYTE)
>1100
250~1100