Vyatta Network OS Documentation

Learn how to install, configure and operate the Vyatta NOS, which helps drive our virtual networking & physical platforms portfolio.


A class defines the packets in a sub-flow — the second stage of classification.

Classes are numbered 0 to 255. QoS determines the class in the first stage of classification where a set of packet matching rules decide which numbered class to assign a packet to.

You cannot configure a class with the value of 0. Class 0 is the default class and uses the default profile — that is, class 0 is reserved for default traffic, such as traffic that does not fall into any other classes.

Note: The hardware does not support multiple classes, so all traffic will fall into class 0 and thus use the default profile.

QoS will try to match classes in numerical order, starting at class 1.

Note: For the sake of efficiency, it is better for QoS to check the classes that handle the most packets first. So, make sure that your lowest-numbered classes are those that you expect to handle the most packets.