User Manual - Configuration Guide (Volume 3)
Versatile Routing Platform Chapter 3
Congestion Management
3-8
II. Configuring priority queue
Priority queue includes the definition for a group of prior ity queues and it specifies in
which queue a packet is placed and the maximum length of different priority queues .
To complete the queuing of a priority queue, you must allocate this list to the interface.
The same priority queue can be applied to multiple interfaces . Certainly, you can create
multiple different priority policies to be applied to different interfaces.
16 groups can be configured in the priority list at most (that is, the value range of the
list-number is 1-16). In each group, the following information is specif ied: what kind of
packets enters what kind of queue, length of each queue, the number of the bytes that
can be sent continuously from the respective queues in each polling, etc.
The priority queue can be defined as four levels: high, me dium, normal and low.
Packets will be forwarded by the level sequence. That is, after all the packets in the
high queue are sent out, send all the packets in the medium queue, and then send all
the packets in the normal queue, and at last send the packets in the low queue.
Priority queue can be configured according to the modes below.
1) Configure priority queue according to network layer protocols
Data packets can be classified according to different types of protocols to make them
enter different priority queues.
Perform the following task in the global configuration mode.
Table QC-3-2 Configure the priority queue according to the network layer protocol
Operation Command
Configure the priority queue according to the
network layer protocol priority-list list-number protocol protocol-name { high | medium
| normal | low } [ queue-keyword keyword-value ]
Delete classification policy in the priority
queues no priority-list list-number protocol protocol-name { high |
medium | normal | low } [ queue-keyword keyword-value ]
No priority queue is established by default.
Here, list-number is the group number of priority queue. protocol-name is the nam e of
the protocol, the value of which can be IP and IPX at present.
When protocol-name is IP, the value of queue-keyword and keyword-value is shown in
the table below.
Table QC-3-3 Value of queue-keyword and keyword-value in IP
queue-keyword keyword-value Meaning
Null Null If it is an IP packet, it enters the queue.
fragments Null If it is a fragmentary IP packet, it enters the priority queue
list access-list-number IP packet in compliance with a specific access-list-number (normal)
definition enters the priority queue.
lt Length Value IP packet whose length is smaller than a count value enters the priority
queue.
gt Length Value IP packet whose length is larger than a count value enters the priority queue.
tcp Port No. If the source of IP packet or destination TCP port number is the specified port
number, the packet enters the queue.
udp Port No. If the source of IP packet or destination UDP port number is the specified
port number, the packet enters the priority queue.