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Configuring CoS Traffic Classification for Ingress Queuing on Oversubscribed Ports on EX8200 Line Cards (CLI Procedure)


EX8200 switches provide certain line cards that include oversubscribed ports. These ports are logically grouped into a port group and each port group share a certain fixed bandwidth. Because oversubscribed ports handle traffic differently than ports that provide continuous line-rate bandwidth, configuring CoS queues is different for oversubscribed ports than for line-rate ports.

Packets arriving on an oversubscribed port in a line card are directed to a high-priority, low priority, or line-rate queue. These queues are used for scheduling traffic from the port into the Packet Forwarding Engine. The fabric priority associated with the packet’s forwarding class determines which queue the packet is sent to. The forwarding class of the packet in turn is determined by the behavior aggregate (BA) classifier assigned to the port. By default, the fabric priority of all forwarding classes is low. Thus all packets, with the exception of critical network packets and line-rate packets, are sent to the low-priority ingress queue by default. The critical network packets and line-rate packets do not need a BA classifier as they are always sent on the high-priority and line-rate queues, respectively.

This procedure describes how you can direct traffic into the high-priority ingress queue and thus avoid congestion at the port group.

To direct traffic to the high-priority ingress queue for a port group:

  1. Create the BA classifier for the forwarding class:
  2. Assign a queue number and fabric priority to the forwarding class:
  3. Assign the BA classifier to the physical interface:

For example, to direct voice traffic to the high-priority ingress queue for interface xe-1/0/2:


You must use a BA classifier to classify traffic for ingress queuing. Multifield (MF) classification and port classification (that is, assigning a forwarding class to the interface) are not supported for classifying traffic for ingress queuing. The BA classifier must be assigned to a physical interface, not a Layer 3 tagged interface or a routed VLAN interface (RVI).