Configuring custom queuing is similar to configuring priority queuing, but instead of completing
three tasks, you must complete five. As with priority queuing, you have to configure a list
to separate types of incoming traffic into their desired queues. After that, you must configure a
default queue for the traffic that will be unassigned to any of the other queues. After the specific
and default queues are defined, you can adjust the capacity or size of each queue or just stick
with the default settings.
When that’s complete, specify the transfer rate, or byte count, for each queue. This is important—
the byte count determines the percentage of bandwidth reserved for a specified queue, with a default
of 1,500 bytes as the denominator. After these parameters are set, apply them to an interface.
The commands used to configure the queuing list, default queue, queue size, and transmit
rate follow:
queue-list list-number default queue-number
queue-list list-number interface interface-type interface-number queue-number
queue-list list-number lowest-custom queue-number
queue-list list-number protocol protocol-name queue-number queue-keyword
keyword-value
queue-list list-number queue [queue-number byte-count byte-count-number | limit
limit-number]
queue-list list-number stun [queue-number | address STUN-group-number]
The syntax can be presented in many ways to configure the desired command. The listnumber
is a value from 1 to 16 and associates the list with the given number. The following are
available options:
default The default option designates a custom queue for packets that do not match another
queue-list.
interface The interface option assigns incoming packets on the specified interface to a
custom queue. When the interface option is specified, you must supply the interfacetype
and interface-number as well. The interface-type is the type of physical interface,
and interface-number is the interface’s physical port.
lowest-custom The lowest-custom option specifies the lowest queue number considered a
custom queue.
protocol The protocol option indicates that the packets are to be sent to the custom queue
if they are of the protocol specified. The protocol option also requires additional information.
Obviously, the protocol-name must be specified. In Table 30.1, a sample of available protocol
names is listed, but available protocols are dependent upon the feature set and version of IOS.
After the protocol-name, you might supply the keyword-value to refine the protocols and
port numbers used for filtering.
queue The queue option allows for specific queue parameters to be configured. The parameters
for the queue are discussed later in this section.
stun The stun option establishes queuing priority for STUN packets.
TABLE 3 0 . 1 Sample of Available Protocol Names
Protocol Name Description
aarp AppleTalk ARP
apollo Apollo
appletalk AppleTalk
arp IP ARP
bridge Bridging
bstun Block Serial Tunnel
cdp Cisco Discovery Protocol
compressedtcp Compressed TCP
decnet DECnet
decnet_node DECnet Node
decnet_router-l1 DECnet Router L1
decnet_router-l2 DECnet Router L2
To define the operational parameters for the custom queues, you use the queue option. After
specifying the queue-number, you’re given two parameters to configure:
limit The limit parameter enables you to change the number of packets allowed in the queue.
The range is from 0 to 32,767, with the default being 20.
byte-count The byte-count parameter specifies the average number of bytes forwarded from
each queue during a queue cycle.