Re: police vs. shape peak

From: John Matus (jmatus@pacbell.net)
Date: Thu Jul 22 2004 - 19:56:37 GMT-3


RE: police vs. shape peak...but if you want traffic to "conform" to a
provisioned rate, which option would be the one, or would both satisfy such a
requirement?

Regards,

John D. Matus
MCSE, CCNP
818.782.2061 office
818.430.8372 mobile
jmatus@pacbell.net

  ----- Original Message -----
  From: Baety Wayne A 30 SIG BN RS3 (cn)
  To: 'John Matus' ; lab
  Sent: Thursday, July 22, 2004 3:56 PM
  Subject: RE: police vs. shape peak

  (1) Police absolutely keeps the traffic rate at a maximum of the configured
rate, by simply dropping packets that exceed the configured rate (or
reclassifying excess packets so that they can later be processed for
dropping).

  (2) Shape portions traffic exceeding the configured rate for later
transmission, queuing the excess traffic, and finally dropping traffic that
overflows the output buffers.

  At points of high constant transmission, shape and police are identical in
operation, dropping excess packets.

  However, since most traffic is bursty in nature, with peaks and valleys in
the traffic rate in relation to the configured rate, shape will defer excess
traffic exceeding the peak rate (each packet sent in each time slice exceeding
the configured byte count) to points of transmission below the configured rate
(time slices in which the byte count quota has not yet been reached).

  In both cases, although the packet classifier has a bitwise precision level,
never are packets chopped up and sent to satisfy a requirement. Whole packets
are either queued (in the case of shaping) or dropped (in the case of
policing).

  Ref: http://www.cisco.com/warp/public/105/policevsshape.html

  WAYNE A. BAETY, Contr, 30SIG BN
  MCSE+I, MCSD, MCDBA, CCNP+Voice
  Resident System Support Specialist
  Office: (808) 655-6761
  Cell: (808) 779-3776

  -----Original Message-----
  From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of John
Matus
  Sent: Thursday, July 22, 2004 11:59 AM
  To: lab
  Subject: police vs. shape peak

  if you have a limit on the amount of traffic that you can send.....or, the
  traffice must "conform" to a certain rate.......would you use

  policy-map null
    class class-default
    police 250000

  or

  policy-map null
    class class-defualt
    shape peak 250000

  what would be the difference??

  Regards,

  John D. Matus
  MCSE, CCNP
  818.782.2061 office
  818.430.8372 mobile
  jmatus@pacbell.net

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