3Com Switch 7754, Configuration Manual

Page: 663 / 940

Overview 663
Two token buckets are used in this evaluation. Their rates of putting tokens into
the buckets are CIR and PIR respectively, and their sizes are CBS and EBS
respectively (the two buckets are called C bucket and E bucket respectively for
short), representing different permitted burst levels. In each evaluation, you can
implement different regulation policies in different conditions, including “enough
tokens in C bucket”, “insufficient tokens in C bucket but enough tokens in E
bucket” and “insufficient tokens in both C bucket and E bucket”.
TP
The typical application of TP is to supervise the specification of certain traffic into
the network and limit it within a reasonable range, or to punish the extra traffic.
Therefore, the network resources and the interests of the operators are protected.
For example, you can limit HTTP packets within 50% of the network bandwidth. If
the traffic of a certain connection is excess, TP can choose to drop the packets or
to reset the priority of the packets.
TP is widely used in policing the traffic into the network of internet service
providers (ISP).TP can classify the policed traffic and perform pre-defined policing
actions according to different evaluation results. These actions include:
■
Forward: Forward the packets although the evaluation result is “incompliant”.
■
Drop: Drop the packets whose evaluation result is “incompliant”.
■
Remark the DSCP precedence and then forward: Modify the DSCP precedence
of the packets whose evaluation result is “incompliant” and then forward
them.
Redirect You can re-specify the forwarding port of packets as required by your own QoS
policy.
Queue Scheduling When the network is congested, the problem that many packets compete for
resources must be solved, usually in the way of queue scheduling.