From: Yasser Abdullah (yasser@alharbitelecom.com)
Date: Thu Apr 15 2004 - 11:02:19 GMT-3
Karim,
First thing to remember when policing, burst is in Bytes (unlike
Traffic-shaping). So if the ask you to allow a burst of 1/4 128K (which
is 32000 bits/sec) then you just need to change the burst size into
bytes. That mean 32000/8 = 4000 bytes.
HTH,
Yasser
-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Karim
Sent: Thursday, April 15, 2004 12:55 PM
To: ccielab@groupstudy.com
Subject: Police/ rate-limit parameters concept confusion
Hi Group,
Required to limit the ICMP traffic to 128K and allow a burst of 1/4 of
this
rate (128000).
The offered solution:
using Rate-limit is:
access-list 100 permit icmp any any
!
interface Ethernet0/0
rate-limit output access-group 100 128000 4000 4000 conform-action
transmit
exceed-action drop
Using MQC:
class-map match-all icmp
match access-group 101
!
policy-map icmp
class icmp
police 128000 bc 4000 conform-action transmit exceed-action drop
OR police 128000 4000 4000 conform-action transmit exceed-action drop
!
access-list 101 permit icmp any any
interface fa0/0
service-policy output icmp
I know that 4000 is taken from 128000/(8*4). I am confused, why it was
solved
as above, I was thinking to solve as follows:
My solution:
Using rate-limit:
access-list 100 permit icmp any any
!
interface Ethernet0/0
rate-limit output access-group 100 128000 16000 20000 conform-action
transmit
exceed-action drop
Parameters calculated as follows:
bc= 128000/8 = 16000. And for busting to 1/4 the 128K, set the be=
16000 +
(16000/4) = 20000.
Using MQC with the same previous parameters:
class-map match-all icmp
match access-group 101
!
policy-map icmp
class icmp
police 128000 bc 16000 be 20000 conform-action transmit exceed-action
drop
!
access-list 101 permit icmp any any
interface fa0/0
service-policy output icmp
Can someone help, why didn't we use the second solution and why is it
wrong
????????
Thanks for your help,
Karim.
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