Vyatta NOS documentation

Learn how to install, configure, and operate Vyatta Network Operating System (Vyatta NOS), which helps to drive our virtual networking and physical platforms portfolio.

traffic-class

This entity introduces strict priority scheduling.

Note: While Vyatta NOS supports 32 queues, only a maximum 8 queues can share the same traffic class. It is possible to have unused traffic classes, that is, have no queues assigned.

Traffic classes are numbered 0 to 3. They provide strict priority queuing within a profile:

  • tc0 is the highest priority and tc3 is the lowest priority.
  • tc0 will send a packet when it has a packet waiting to be sent, and it has not exceeded its bandwidth limit.
  • If tc0 doesn't send a packet for either reason, then tc1 can send a packet.
  • If tc1 doesn't send a packet because it doesn't have a packet waiting to be sent or tc1 has exceeded its bandwidth, then tc2 can send a packet.
  • If tc2 doesn't send a packet because it doesn't have a packet waiting to be sent or tc2 has exceeded its bandwidth, then tc3 can send a packet.

traffic-class at the policy level

Vyatta NOS handles traffic classes in strict priority order, traffic class 0 being the highest priority, 3 being the lowest.

Note:

On software platforms, a policy may have multiple profiles.

At the policy level, the traffic-class entity controls the bandwidth and queue limit across all queues of all the profiles of a particular traffic class.

Sub-entities
  • WRR queues
  • random-detect

The profile queues of the traffic class, at the lowest level of the scheduling hierarchy by default, normally operate as simple FIFO queues. However, you can also configure them to operate as WRED queues.

Note: On software platforms you can set up WRED across all the queues and all the profiles.
Attributes

The queue-limit attributes define how long the profile queues that belong to a particular traffic class are.

  • On software platforms, we express queue-limit as the maximum number of packets that can fit on the queue.
  • On hardware platforms, we express queue-limit-bytes as the total number of bytes of memory that packets in the queue can consume.
  • We express queue-limit-time as the maximum time that a packet can wait on a queue.

traffic-class at the profile level

You can set up bandwidths on a particular traffic class within the profile.

Control bandwidths across all the queues in that traffic class, within the profile.

Vyatta NOS will schedule eight queues within a traffic class in weighted round robin (WRR) order. You can configure queue weights to provide different bandwidth allocations for each queue within a traffic class.