Dynamically assigning service classes for a QOS aware network link

A non-transitory machine readable medium storing a program that when executed by at least one processing unit forwards a packet from a first forwarding node at a first physical site of a wide area network (WAN) to a second forwarding node at a second physical site of the WAN along a physical layer 1 (L1) network link that has a plurality of associated service classes, the program comprising sets of instructions for:

• at the first forwarding node:
• receiving, from the second forwarding node, first and second path quantifying metric (PQM) values respectively for first and second service classes associated with the physical L1 network link at the first physical site, wherein the first and second service classes are associated with different quality of service (QoS) guarantees provided by the WAN to different sets of packet flows passing through the WAN along the physical L1 network link, wherein the first and second PQM values are computed by the second forwarding node;
• based on the first and second PQM values, selecting the first service class for the packet;
• associating the packet with the selected first service class;
• and
• forwarding the packet with the associated first service class to the second forwarding node along the network link.

A method of forwarding a packet from a first forwarding node of a wide area network (WAN) to a second forwarding node of the WAN along a network link that has a plurality of associated service classes, the method comprising:

• identifying a first set of path quantifying metric (PQM) values for a first service class and a second set of PQM values for a second service class, each set of PQM values comprising a plurality of different types of metric values, wherein the first and second service classes are associated with different quality of service (QoS) guarantees provided by the WAN to different sets of packet flows passing through the WAN;
• selecting one type of metric value that is critical for a type of traffic contained in payloads of a packet flow associated with a packet;
• identifying from each identified PQM value set the PQM of the selected type;
• determining that the first PQM value set of the first service class has a better PQM value for the selected type than the second PQM value set of the second service class;
• associating the packet with an identifier identifying the first service class;
• and
• forwarding the packet associated with the first service class to the second forwarding node along the network link.