Committed burst Excess burst

[John lay]

Guys,

I have a question regarding Frame Relay traffic shapping.
I am try to understand the difference between the Committed Burst and the
Excess Burst. I have been reading the BCRAN training material for that part,
but the difference is not clear enough till now.
Any simple claification on this issue is highly appreciated.

Thanks in advance. 





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Re: Committed burst Excess burst

[George Garay]

John,

Commited Burst is the maximum amount of data (in bits) that the network
agrees to transfer, under normal conditions.  This data has priority under
conditions of congestion.  Excess Burst is the maximum amount of uncommitted
data (in bits) in excess of Commited bursts that a frame relay network can
attempt to deliver during a time interval.  Excess bursts data has a
user-set bit indicating that the frame may be discarded (is set to discard
elegible)in preference to other frames if congestion occurs.  What it all
boils down to is that excess burst frames can be dumped if congestion occurs
so their is no guarantee that they will make it.  You usually set this
amount with your provider (i.e. 128k commited/256k Excess)when ordering your
frame circuit.

hope this helps

George Garay  CCNA
[EMAIL PROTECTED]
John lay [EMAIL PROTECTED] wrote in message
[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
 Guys,

 I have a question regarding Frame Relay traffic shapping.
 I am try to understand the difference between the Committed Burst and the
 Excess Burst. I have been reading the BCRAN training material for that
part,
 but the difference is not clear enough till now.
 Any simple claification on this issue is highly appreciated.

 Thanks in advance.





 ___
 Say Bye to Slow Internet!
 http://www.home.com/xinbox/signup.html

 _
 FAQ, list archives, and subscription info:
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 Report misconduct and Nondisclosure violations to [EMAIL PROTECTED]



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RE: Committed burst Excess burst

[Coker, Michael]

Let me attempt to explain it:

There are three components to Frame Relay traffic shaping and the Frame
Relay standard for discarding packets, although not often used in producion
Frame Relay environments:

Bc = Committed Burst
Be = Excessive Burst
Tc = Time Interval

The Bc is similar to that of the CIR except it is an "amount" of data,
represented in bits, whereas the CIR is an amount of data transmitted per
second.  

The Be is also represented as an "amount" of data, represented in bits.

The Tc is the time interval in which this process will take place.

Now for the process:

As frames are received by the Frame Relay switch it uses an algorithm known
as the leacky bucket algorith, similar to ATM, to track and monitor the
amount of data being sent from a DLCI.

Note:  This entire process takes place within a specific amount of time,
known as the Tc.  Once the Tc has expired, the process is repeated for the
next amount of data.

Think of the Bc and Be as buffers for the frames.  As the data is received
by the Frame Relay switch from a specific DLCI it will fill up the Bc buffer
first.  All packets after the Bc fill up the Be buffer and are marked as DE
(Discard Eligible).  After the Be is filled, the frames are discarded until
the Tc expires.  The process is then repeated.

Hope this clarifies things.  Feel free to send me an e-mail if you need/want
further clarification.  I've also got a Visio diagram that illustrates this
process.

Best Regards,

--Mike
 

-Original Message-
From: John lay
To: [EMAIL PROTECTED]
Sent: 11/2/00 1:56 AM
Subject: Committed burst  Excess burst

Guys,

I have a question regarding Frame Relay traffic shapping.
I am try to understand the difference between the Committed Burst and
the
Excess Burst. I have been reading the BCRAN training material for that
part,
but the difference is not clear enough till now.
Any simple claification on this issue is highly appreciated.

Thanks in advance. 





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