From: Victor Cappuccio (cvictor@protokolgroup.com)
Date: Wed Aug 30 2006 - 05:33:22 ART
Hi HaDucBinh,
This is From Chris Lewis a List Member of this great GroupStudy
http://www.groupstudy.com/archives/ccielab/200603/msg00203.html
"Bc is just the depth of the bucket used for the policing algorithm. It is
not an extra amount of traffic that can be continually sent."
That being said, 16000 Bytes should be allowed to be sent in a Burst, that
mean, if you only send 1 packet (Pkt) of 16000 Bytes packet that packet is
marked as Green, or if I send 2 Pkts in T=0 and both equal to 16000 Bytes in
Size, they still conform. But if 1 pkt is greater or equal to 16001 the
packet is marked as red and ends in /dev/null by default. You can do also
other actions.
Policing calculations are driven by Pkt arrival times.
http://www.cisco.com/univercd/cc/td/doc/product/software/ios123/123tcr/123tq
r//qos_o1gt.htm#wp1084420
That means that the system would add Tokens to the Bucket using the
following formula (time between packets <which is equal to T - T1> * policer
rate)/8 bytes
If I send a Pkt of 16000 bytes in sec 0 then I would consume all Bytes in
The Token Bucket, so I have to wait almost nothing because you have
configured a Higher Cir, which would be replenish of Tokens very quick
For example if I have configure this cir 8000 bps, bc 1000 bytes in one
router, I would add 8000/8 worth token into the Token Bucket if T=1
That means if I send a Pkt of (996 + all the headers) in time 0 and then
wait for 1 sec and send the other both would be marker as green
So I almost have to wait like 1 sec and a little bit to allow another pkt
with a 1000 bytes of Size (or a burst of small packets in that time and with
a total weight of 1000 bytes)
As you can see here, there is a direct relation between the CIR configured,
the BC Value and the Time the Pkt arrives
I hope this make much sense now, there is a lots of fun in Policing using
RFC 2697 and 2698, and the key here is to remember that both are metering
systems that helps us keep the contracted CIR over a long Run.
Victor.-
-----Mensaje original-----
De: nobody@groupstudy.com [mailto:nobody@groupstudy.com] En nombre de
haducbinh
Enviado el: Miircoles, 30 de Agosto de 2006 12:26 a.m.
Para: ccielab@groupstudy.com
Asunto: Police QoS
Dear group!
I'm configuring QoS and confusing about "police" command in MQC policy-map,
the command like this:
Policy Map POLICY_85
class class-default
police 1000000 16000 exceed-action drop
I don't understand deeply the number 16000 what does it mean?
Could I use another number? For example: police 1000000 24000 exceed-action
drop
Please explain me!
Thanks!
HaDucBinh
Mail: haducbinh@vnpro.org or haducbinh@yahoo.com
Phone: 0908 191 322
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