Nortel 450-24t 用户指南
BayStack 450 10/100/1000 Series Switches
309978-D Rev 01
1-75
Figure 1-44.
Port Transmit Queue
As shown in Figure 1-44, the switch provides two transmission queues, High and
Low, for any given port. Frames are assigned to one of these queues on the basis of
the user_priority value, using a traffic class table. This table is managed by using
the Traffic Class Configuration screen (Figure 1-45). The table indicates the
corresponding traffic class that is assigned to the frame, for each possible
user_priority value. If the frame leaves the switch formatted as a tagged packet,
the traffic class assigned to the frame is carried forward to the next 802.1p-capable
switch. This allows the packet to carry the assigned traffic class priority through
the network until it reaches its destination.
Low, for any given port. Frames are assigned to one of these queues on the basis of
the user_priority value, using a traffic class table. This table is managed by using
the Traffic Class Configuration screen (Figure 1-45). The table indicates the
corresponding traffic class that is assigned to the frame, for each possible
user_priority value. If the frame leaves the switch formatted as a tagged packet,
the traffic class assigned to the frame is carried forward to the next 802.1p-capable
switch. This allows the packet to carry the assigned traffic class priority through
the network until it reaches its destination.
The following steps show how to use the Traffic Class Configuration screen to
configure the port priority level shown in Figure 1-43.
configure the port priority level shown in Figure 1-43.
For more information about using the Traffic Class Configuration screen, see
“Traffic Class Configuration” on page 3-57.
“Traffic Class Configuration” on page 3-57.
BS45025A
User priority
(6)
Port
transmit
queue
High
High priority
packet
Port 5
Traffic
class
7
6
5
4
6
5
4
3
2
1
0
2
1
0
Low