Description

Do multifield classifiers override behavior aggregate classifiers on Juniper routers?

Symptoms

Between multifield (MF) classifier and behavior aggregate (BA) classifier, which will take precedence?

Solution

Traffic entering a Juniper router (M, MX & T Series) or firewall (J-Series and SRX) will be classified in the following order:

  1. Packet is first classified based on BA classifier and code-points.
  2. Next packet is checked for any MF classifiers. If one exists it overrides the BA classifier and sends the packet to the queue as defined in MF classifier.
  3. If there is no MF classifier then the packet follows the BA classifier queueing.
NOTE: For a specified interface, you can configure both a MF classifier and a BA classifier without conflicts.  Because the classifiers are always applied in sequential order, the BA classifier followed by the MF classifier, any BA classification result is overridden by an MF classifier if they conflict.