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Thanks for you input. If you follow recent
discussions there is a proposal to use extension headers in ULE to support
system specific signalling (and other). It would be interesting to know more
about how you process the information but I think our philosophy would be to use
the headers in the same way as you describe: transparent to system who do not
know what to do with them, processed by the ones who do. This is consistent with
IPv6 extension headers and also with other implementations of extension headers
(cable for example).
So I do believe we could use ULE in RCS. Actually
in a recent study sponsored by ESA we showed that for traffic with a lot of ACK
bursts (http: for example) ULE was very efficient because of it's packing
capability.
Again thanks for your input.
Marie-Jose
----- Original Message -----
Sent: Tuesday, April 13, 2004 3:02
AM
Subject: Adaptation field use in ULE /
MPG2-TS specification
Hello,
I am jumping into this discussion at a fairly late
stage. Having just read the ULE draft I have to make a comment about the use
of the adaptation field though. In the draft it says that "TS Packets from a
ULE Encapsulator MUST be sent with an AFC value of '01'", i.e. without
adaptation field. Now the adaptation field contains a private field which
according to the MPG2-TS specification (ISO/IEC 13818-1) can be used to
transmit system dependent data.
Now to the question: Why is this limitation imposed on ULE?
I have two main reasons to
ask this.
1) Firstly there is ongoing
work to use the private adaptation field for network internal signalling in
the DVB-RCS standard. This means that ULE will not work over DVB-RCS systems
employing the adaptation field signalling.
2) As far as I have been able to determine all other encapsulation
forms over MPG2-TS are transparent to the adaptation field, i.e. the
adaptation field and payload are handled independently (even though there may
be an implicit connection between them). It seems strange to break this
logicinf the MPG2- TS mechanism for a new encapsulation type.
Best Regards
Tor Brekke
Nera
Broadband Satellite AS.
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