RE: How is the FEC instance ID field in the EXT_FTI headerdefined?

Magnus,

Actually, ETX_FTI is formally defined in (the new) ALC, but that just
defines the Header Extension Type (64) and says that the content is the
"Encoded FEC Object Transmission Information" which (according to the
FEC BB) MUST be defined independently by each FEC Scheme.

So, for FEC Schemes with FEC Encoding ID < 128 they do not need to
include the (redundant) FEC Instance ID.

However, for the previously defined FEC Schemes then in
draft-ietf-rmt-bb-fec-basic-schemes-revised-01.html I defined the
"Encoded FEC Object Transmission Information" to match the previous
definition - in particular for the Compact No-Code, the bytes
corresponding to the FEC Instance ID are included but marked as
reserved. So, we have backwards compatibility for the existing FEC
Schemes and flexibility for future ones.

Regards,

Mark



-----Original Message-----
From: [email protected] [mailto:[email protected]] On Behalf Of
Magnus Westerlund
Sent: Wednesday, January 18, 2006 9:25 AM
To: [email protected]
Subject: [Rmt] How is the FEC instance ID field in the EXT_FTI
headerdefined?

Hi,

Due to the missing LCT revised specification draft version 01 I do have 
to ask this question. It might be answered by that draft, that I don't 
know as I can't get hold of it.

But the real question is: Is the FEC Instance ID field present or not in

the EXT_FTI header when the FEC encoding ID is less than 128? The RFC 
3926 text:
    FEC Instance ID, optional, 16 bits:

    This field is used for FEC Instance ID.  It is only present if the
    value of FEC Encoding ID is in the range of 128-255.  When the value
    of FEC Encoding ID is in the range of 0-127, this field is set to 0.


Which says both that it shouldn't be there and have a value. Please 
clarify this for me.

Cheers

Magnus Westerlund

Multimedia Technologies, Ericsson Research EAB/TVA/A
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Torshamsgatan 23           | Fax   +46 8 7575550
S-164 80 Stockholm, Sweden | mailto: [email protected]

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