H3C S7500 Series Ethernet Switches Operation Manual

Operation Manual – QoS
H3C S7500 Series Ethernet Switches Chapter 1
QoS Configuration
1-5
Byte 1
TPID (Tag Protocol Identifier) TCI (Tag Control Info
Priority cfi V
rmation)
LAN ID
Byte 2Byte 3Byte 4
00 0 00 0 000 0 0 00 00 0
3274 1065 3274 1065 3274 1065
3274 1065
r Figure 1-3 The contents of an 802.1Q tag heade
In the figure above, the 3-bit priority field in the TCI filed is 802.1p priority in the range of
0 to 7.The 3 bits specify the precedence of the frame.8 classes of precedence are used
to determine which frame is to be sent preferentially when congestion occurs on the
switch.
Table 1-3 Description on 802.1p priority
CoS precedence
(decimal)
CoS precedence
(binary)
Description
0 000 best-effort
1 001 background
2 010 spare
3 011 excellent-effort
4 100 controlled-load
5 101 video
6 110 voice
7 111 network-management
The precedence is called 802.1p priority because the related applications of this
precedence are defined in detail in the 802.1p specification.
3) Local precedence
Local precedence is the precedence of an outbound queue on a port of the switch. It is
in the range of 0 to 7. Each outbound queue has its corresponding local precedence.
1.1.4 Priority of Protocol Packets
Each protocol packet carries its own priority. You can perform QoS actions for protocol
packets by setting their priorities.
1.1.5 Priority Marking
The priority marking feature is to use ACL rules for traffic identification and remark the
priority for the packets matching the ACL rules.