Priority Of Protocol Packets; Priority Marking - H3C S7500 Series Operation Manual

Operation Manual – QoS
H3C S7500 Series Ethernet Switches
Byte 1
0 0 0
7 6 5
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
0
1
2
3
4
5
6
7
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.
Byte 2
TPID (Tag Protocol Identifier)
0 0 0 0 0 0 0 0 0 0
4 3 2 1 0 7 6 5 4
(decimal)
000
001
010
011
100
101
110
111
Byte 3
TCI (Tag Control Info
0 0 0 Priority
3 2 1 0 7 6 5 4 3 2
r
CoS precedence
(binary)
1-5
Chapter 1 QoS Configuration
Byte 4
rmation)
cfi V LAN ID
1 0 7 6 5 4 3 2
Description
best-effort
background
spare
excellent-effort
controlled-load
video
voice
network-management
1 0