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Fwd: Urgent Help Needed...

  • From: Roger Clark Williams <rogerw@nordlink.com>
  • Date: Tue, 18 Mar 2003 16:00:15 -0500
  • Resent-Date: Tue, 18 Mar 2003 17:09:49 -0500
  • To: MPLS-ops Mailing List <mpls-ops@mplsrc.com>
  • X-Sender: rogerw@together.net@pop.mindspring.com

Muzammil, do not forget overhead. Your formula may be correct in general, but every system will have certain overhead (keep-alives, hellos, routing updates). These do not count for customer data throughput but they do count when thinking of overall bandwidth demand.

Also, your formula would want to read "number of packets/time". This will give you the average.

Some other points to keep in mind: Average throughput may not reflect total possible throughput over a link (think about the effect of TCP windowing and slow start on the average). Also, average over a longer period (say an hour) may be below short peaks. If you are working on throughput, these peaks can be critical depending on the type of traffic. For example, peaks may mean packets get dropped. No real problem for FTP, but definitely a potential problem for streaming media or VoIP. Your hourly average may say that there is plenty of bandwidth available for such traffic, yet you find that VoIP is not working well.

All this comes to say that you should beware of being too simplistic in your model. Real life factors that are not shown in the simple formula affect the throughput.

I hope this is helpful.

Roger Williams



Resent-Date: Tue, 18 Mar 2003 08:35:25 -0500
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Reply-To: "Muzammil Ahmad Khan" <mukhan@ssuet.edu.pk>
From: "Muzammil Ahmad Khan" <mukhan@ssuet.edu.pk>
To: "john smith" <johnsmith0302@hotmail.com>
Cc: <mpls-ops@mplsrc.com>
Date: Tue, 18 Mar 2003 18:27:34 +0500
Organization: Sir Syed University of Engineering and Technology.
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Subject: [MPLS-OPS]: Urgent Help Needed...
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X-Mailing-List: <mpls-ops@mplsrc.com> archive/latest/5439
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Hello,
 
I am working on the quantitative analysis of MPLS VPN.
In this analysis i want to have a comparision of a network having a VPN network with another network having MPLS network.
In this analysis i want to have the comparision of these two networks with respect to THROUGHPUT.
 
Now, the probelm is that i want to make sure that whether i am using the correct formula for the calculation of the throughput or not.
 
I am using the formula
 
Throughput =  Average number of packets received / Time
 
 
Please  confirm me that whether this formula is correct or not.
 
Waiting for urgent reply.
 
Regards,
Muzammil Ahmad Khan
 
 
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