Custom Queuing Classification

Custom Queuing Classification

• Custom queuing classification for IP includes these options:
• Source interface
• IP access list (standard and extended)
• Packet size (greater or smaller than specified)
• Fragments
• TCP source or destination port numbers
• UDP source or destination port numbers
• Custom queuing classification is identical to that of Priority queuing.

Custom Queuing Insertion Policy

• Each queue has a maximum number of packets that it can hold (queue size).
• After a packet is classified to one of the following queues, the router will enqueue the packet if the queue limit has not been reached (tail-drop within each class).

Custom Queuing Scheduling

• Custom queuing uses a round-robin service policy.
• Each queue is allowed to forward a configurable amount of bytes (threshold) in one round.

• Packet in
• Queue N?

• Hardware Q

• Yes

• No

• Dispatch
• Packet

• Is Queue N
• over the
• threshold?

• No

• Next Queue
• (increase N)

• Yes

Custom Queuing Scheduling Parameters

• The threshold (byte-count) parameter specifies the lower boundary on how many bytes the system allows to be delivered from a given queue during a particular cycle.
• The router is allowed to send the entire packet even if the sum of all bytes is more than the threshold.

• 1500

• 1499

• 1500

• Threshold (byte-count) = 3000

• Up to 4499 bytes can be forwarded in one round in the worst case.