Subject: [Megaco] what is ALF ( Application Level Framing )

From: "sunil vatnal" <[email-masked]>
Date: Tue, 17 Jun 2003 13:06:40 +0530

Hi,

The megaco RFC 3015 suggests to implement ALF ( Application Level Framing ) for the UDP transport. The meaning of the ALF is like this in the RFC.

" ALF is a set of techniques that allows an application, as opposed to a stack, to affect how messages are sent to the other side. A typical ALF technique is to allow an application to change the order of messages sent when there is a queue after it has queued them.  There is no formal specification for ALF. 
   Implementors using IP/UDP with ALF SHOULD be aware of the restrictions of the MTU on the maximum message size. "

Most of the Megaco Protocol Stack developers say that they have achieved the ALF by implementing reliable transactions by having retransmissions, provisional transmissions, rejection of duplicate transactions...etc.

My Question is .... ===> Can we achieve ALF by .. 

   1) implementing reliable transactions with retransmission techniques with long timer
       mechanism ( This is already implemented )

                                            -- OR -- 

   2) Fragment and reassemble the message or the media data depending upon the MTU size.
   
                                            -- OR --
   3) Divide the message or the media data into ADUs ( Application Data Units ) and keep track 
       of the order of these.

   Please clarify..

  Thanks and Regards,
  Sunil M Vatnal
  Mahindra British Telecom.

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