IBM 12.1(22)EA6 User Manual

Actions at the egress interface include queueing and scheduling:

Queueing evaluates the CoS value and determines which of the four egress queues in which to place 
the packet.

Scheduling services the four egress queues based on their configured weighted round robin (WRR) 
weights. 

Classification is the process of distinguishing one kind of traffic from another by examining the fields 
in the packet. 

Classification occurs only on a physical interface basis. No support exists for classifying packets at the 
VLAN level.

You specify which fields in the frame or packet that you want to use to classify incoming traffic. 

For non-IP traffic, you have these classification options:

Use the port default. If the frame does not contain a CoS value, the switch assigns the default port 
CoS value to the incoming frame.

Trust the CoS value in the incoming frame (configure the port to trust CoS). Layer 2 IEEE 802.1Q 
frame headers carry the CoS value in the three most-significant bits of the Tag Control Information 
field. CoS values range from 0 for low priority to 7 for high priority.

The trust DSCP configuration is meaningless for non-IP traffic. If you configure a port with this 
option and non-IP traffic is received, the switch assigns the default port CoS value and classifies 
traffic based on the CoS value. 

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Classification

Policing

Actions at ingress

Actions at egress

Mark

In profile or

out of profile

Classifies the packet 
based on the ACL.

Determines if the 
packet is in profile or 
out of profile based 
on the policer 
associated with the 
filter.

Based on whether 
the packet is in or 
out of profile and the 
configured 
parameters, 
determines whether 
to pass through, 
mark down, or drop 
the packet.  The 
DSCP and CoS are 
marked or changed 
accordingly.

Queuing and

scheduling

Based on the CoS, 
determines into 
which of the egress 
queues to place the 
packet, then 
services the queues 
according to the 
configured weights.