Mohamed Saro wrote:
> what is the difference and the direction of rate-limit and traffic shapping
If you're looking for definitions, try this from RFC 3290 (p. 12):
Diffserv nodes may apply shaping, policing and/or marking to traffic
streams that exceed the bounds of their TCS in order to prevent one
traffic stream from seizing more than its share of resources from a
Diffserv network. In this model, Shaping, sometimes considered as a
TC action, is treated as a function of queuing elements - see section
7. Algorithmic Dropping techniques (e.g., RED) are similarly treated
since they are often closely associated with queues. Policing is
modeled as either a concatenation of a Meter with an Absolute Dropper
or as a concatenation of an Algorithmic Dropper with a Scheduler.
These elements will discard packets which exceed the TCS.
The glossary (section 2) also defines "work-conserving" and
non-work-conserving", regarding whether or not packets will continue to
be sent when the link is idle:
Non-work- A property of a scheduling algorithm such that it
conserving services packets no sooner than a scheduled departure
time, even if this means leaving packets queued
while the output (e.g., a network link or connection
to the next element) is idle.
Work- A property of a scheduling algorithm such that it
conserving services a packet, if one is available, at every
transmission opportunity.
Shaping The process of delaying packets within a traffic stream
to cause it to conform to some defined temporal
profile. Shaping can be implemented using a queue
serviced by a non-work-conserving scheduling algorithm.
Those are the accepted definitions for purposes of clarifying the discussion
of Diffserv. If someone wants to use a different definition, no problema,
but we only need to know what it is.
"All definitions are created equal." Some are used more than others,
depending on the discussion.
-- TT
Message Posted at:
http://www.groupstudy.com/form/read.php?f=7&i=52679&t=52468
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