As the ipdvb WG Chair, let me see if I can frame some questions to the
WG as a whole (dervied from my understanding of this mail thread)? -
This isn't an intention to stop discussions (we should address some of
the issues raised onm the lists in the documents we plan to write), but
I am aware that we have a document to deliver to the IESG following the
WGLC.
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My three questions are:
A) There was a proposal by a reviewer to change the TITLE of the RFC, to
make this clearer. The currently suggested new title is:
"Ultra Lightweight Encapsulation (ULE) for transmission of
IP datagrams over an MPEG-2 Transport Stream"
Instead of the existing title:
"Ultra Lightweight Encapsulation (ULE) for transmission of
IP datagrams over MPEG-2/DVB networks"
Is the new title acceptable?
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B) I propose the following text is added to the Introduction, are these
useful/sufficient?
The MPEG-2 specification [ISO-MPEG2] requires conformant TS
Multiplexes to provide Program Specific Information (PSI) for
each stream in the TS Multiplex. Other MPEG-2 based transmission
standards may also define Service Information (SI). This
information may allow Receivers and Re-multiplexors [draft-ipdvb-arch]
to locate a specific ULE Stream (i.e., the PID value of the TS Logical
Channel that carries a ULE Stream). The conditions under which this
information is required, and the format in which it is to be provided
is beyond the scope of this document. Addressing and mapping issues
for IP over MPEG-2 are described in [draft-ipdvb-ar].
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C) The terminology "TS Logical Channel" has already been used in another
document that has passed WGLC. Is it now sufficiently flawed that we
MUST be replaced in the ULE document, if so why?, If not, I propose we
change the definition to:
TS Logical Channel: Transport Stream Logical Channel. In this
document, this term identifies a channel at the MPEG-2 level [ISO-
MPEG2]. This exists at level 2 of the ISO/OSI reference model. All
packets sent over a TS Logical Channel carry the same PID value
(this value is unique within a specific TS Multiplex). The term
"Stream" is defined in MPEG-2 [ISO-MPEG2]. This describes the content
carried by a specific TS Logical Channel (see, ULE Stream). Some
PID values are reserved (by MPEG-2) for specific signalling.
Other standards (e.g., ATSC, DVB) also reserve specific PID values.
I propose we also add:
ULE Stream: An MPEG-2 TS Logical Channel that carries only ULE
encapsulated PDUs. ULE Streams may be identified by definition
of a ULE stream_type in SI/PSI [ISO_MPEG2].
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A number of minor corrections have also been made to wording and format,
as requested by the various reviewers and WG feedback.
The complete set of proposed changes are listed at:
http://www.erg.abdn.ac.uk/ip-dvb/ids/rfcdiff-ule-05f-04.html
Please respond whether you think this revision, is now ready, and we'll
try to reach a conclusion on whether this document is finally ready to
submit.
Gorry Fairhurst
(ipdvb WG Chair)