RE: QOS Aggregate

From: Phillip.McCollum@ins.com
Date: Tue Dec 11 2007 - 00:25:00 ART


Frank,

My mistake on the last post.. The burst is definitely in bytes. So for 2
MegaBITS per second (2,000,000 BITS), you would need to burst 250,000
BYTES per interval to meet that average police rate.

Did that clear it up? J

Phillip

From: Frank CCIE [mailto:frankccie@gmail.com]
Sent: Monday, December 10, 2007 6:38 PM
To: McCollum, Phillip
Cc: DAthaide@eprod.com; ccielab@groupstudy.com
Subject: Re: QOS Aggregate

Hi, Phillip,

Is the burst in Byte or bps? In your formula and Solution 1 and 2,
Burst is in bps in .125 ms.

DocCD shows the normal burst size in bytes. I am little confused.

Thanks

Frank

On Dec 10, 2007 2:46 PM, <Phillip.McCollum@ins.com> wrote:

Dwayne,

The minimum burst to sustain the policing rate is determined by the
following formula:

Burstmin (bits) = Rate (bps) / Interval (1/sec)

Remember that the interval is fixed at .125 ms (8 intervals per second)

1.) Burstmin = 2000000 / 8 (intervals) = 250000 (bits per interval)
2.) Burstmin = 3000000 / 8 (intervals) = 375000 (bits per interval)

For question 1, your choice would allow you to send 2Mpbs of data in
only 2 intervals (250 ms), before policing would kick in... For question
2, your choice would allow you to send 3Mbps of data in 3 intervals (375

ms), before policing would kick in.

Hope this made some sense...

HTH,
Phillip

-----Original Message-----
From: nobody@groupstudy.com [mailto:nobody@groupstudy.com] On Behalf Of
Athaide, Dwayne
Sent: Monday, December 10, 2007 11:13 AM
To: Cisco certification
Subject: QOS Aggregate

Below are two scenario I ran into in my practice workbook. Please let
me know if my solution is correct and any reason its not thanks

Question states

VLAN B should allow no more than 2mb total throughput. Would my
solution still be correct? Where did they get the 250000 in Solution 1
and 375000 in Solution 2?

My solution

mls qos aggregate-policer AGG 2000000 1000000 exceed-action drop

!

policy-map POLICE-AGG

 class class-default

   police aggregate AGG

interface FastEthernet0/1

 switchport access vlan 12

 service-policy input POLICE-AGG

!

interface FastEthernet0/2

 switchport access vlan 12

 service-policy input POLICE-AGG

Solution guide

mls qos aggregate-policer VLANB 2000000 250000 exceed-action drop

!

class-map match-all B

 match vlan 12

 match class-map class-default

!

!

policy-map MyQoS

 class B

   police aggregate VLANB

interface FastEthernet0/1

 switchport access vlan 12

 service-policy input MYQOS!

interface FastEthernet0/2

 switchport access vlan 12

 service-policy input MYQOS

Question 2 : Vlan D should make sure that any speaker will not flood the
LAN with more than 3MB of traffic at a time

My solution

mls qos aggregate-policer VLAND 3000000 1000000 exceed-action drop

policy-map AGG

 class class-default

   police aggregate VLAND

Service policy applied inbound on ports in the VLAN

Solution guide

policy-map VLAND

 class class-default

   police 3000000 375000 exceed-action drop



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