Queuing Overview 303
There is another way to assign specific traffic to a particular queue. Example 10-2 places Telnet
into the high queue, but without the use of access lists.
The keyword tcp and the value 23 specify Telnet traffic without having to utilize an access list.
Other valid keywords are as follows:
·
gt--Signifies that values greater than or equal to the specified number should be
considered a match for the priority list line.
·
lt--Signifies that values less than or equal to the specified number should be considered
a match for the priority list line.
·
List--Checks the access list number as specified in this line.
·
tcp--Dictates that the specified Transmission Control Protocol (TCP) port number should
be considered a match for this priority list line.
·
udp--Dictates that the specified User Datagram Protocol (UDP) port number should be
considered a match for this priority list line.
All other IP traffic (that is, non-Telnet) is placed in the medium queue, as is IPX. AppleTalk is
placed in the normal queue. The queue does not activate until applied to the serial interface.
You can also specify that any traffic that entered the router through a particular interface be
placed into a particular queue by using the following command structure:
RouterA(config)#priority-list list-number interface interface-type
interface-number {high | medium | normal | low}
NOTE
The positioning of commands is imperative. The queue list is processed line by line. The first
time a packet matches a line in the list, it is sorted based on that line. In Example 10-3, for
example, if the line placing IP in the medium queue was entered prior to the lines placing Telnet
in the high queue, all Telnet traffic would be placed in the medium queue rather than in the high
queue.
The easiest way to explain the use of this command is with a example. Example 10-3 shows the
use of this command in conjunction with the configuration in Example 10-1.
Example 10-2
priority-list Configuration without Access Lists
RouterA(config)#priority-list 1 protocol ip high tcp 23
RouterA(config)#priority-list 1 protocol ip medium
RouterA(config)#priority-list 1 protocol ipx medium
RouterA(config)#priority-list 1 protocol Appletalk normal
RouterA(config)#interface serial 0
RouterA(config-if)#priority-group 1