notes: Legacy Custom Queuing

 

- Implementation of weighted round robin.
- Up to 16 configurable queues, including a priority queue.
- Thresholds are based on the number of bytes and/or number of packets.
- CQ is prone to inaccurate bandwidth allocations.
- Can only apply one mechanism per interface. MQC changes this.
- The custom queue is used to create a bandwidth reservation in the output queue based on the configured queues.
- With the custom queue it is important to note that the behaviour of the queueing mechanism only becomes evident when the output queue is congested.
- Each configured queue is guaranteed only the minimum configured amount, but can utilize all unused bandwidth.
- Because queueing is always outbound, when custom queueing applied to the interface, no direction can be specified.
- The queueing strategy will be 'custom-list', as seen with "sh interface".
- Queue 0 is like a priority queue. Traffic in this queue will always be sent first.
- 0 - 16: are configurable queues.

Defaults:
>> Byte-count = 1500 bytes
>> Queue-limit = 20 packets

commands: 

Router(config)# queue-list 1 protocol ip 1 tcp www
Router(config)# queue-list 1 protocol ip 2 tcp telnet
Router(config)# queue-list 1 default 3
Router(config)# queue-list 1 queue 1 byte-count 1500 limit 512

Router(config)# queue-list 1 queue 2 byte-count 1500 limit 512
Router(config)# queue-list 1 queue 3 byte-count 3000 limit 512
!
Router(config)# interface serial 0/1
Router(config-if)# bandwidth 128
Router(config-if)# custom-queue-list 1

 

Total number of bytes serviced during each round-robin cycle = 1500 + 1500 + 3000 = 6000
Percentage of bandwidth for World Wide Web traffic = 1500 / 6000 = .25 = 25 percent
Percentage of bandwidth for Telnet traffic = 1500 / 6000 = .25 = 25 percent
Percentage of bandwidth for default traffic = 3000 / 6000 = .5 = 50 percent

verification:

- Shows the queueing strategy and configured queues

sh interface {int}

- Shows the custom queue configuration

sh queueing custom

- Shows the current queue contents

sh queue {int} [queue no]