Re: Switching mpeg2 packets on satellite

[Gorry Fairhurst <gorry@erg.abdn.ac.uk>]

See in-line comments

Ghassane Aniba wrote:
> 
> HI,
> First, if we want switch the mpeg packet on the satellite, we need to
> add a label to distinguish between the differents flows.

> With a new generation of satellite OBP(OnBoard Processor), with
> multi-spots, we need a label in each TS Packet, to switch packet to the
> spots interested by this packet. 

Yes, you refer to an interesting case. There are going to be very many
different variants ion the future... For instance, I would not be in the
least surprised to find MPEG-2 remultiplexors in terrestrial DVB-T networks
which also want to "route" packets based on a PID to different broadcast
cells.

So where does your label go in the SI table associated with a PID,
or in each SNDU "tag"???

This comes down to:

- Should you be switching at then PID level? - i.e. PID represents a 
destination - that would make sense - at least for unicast.

- Should you be switching on a packet by packet level
WITHIN a TS stream (shared PID), forwarding some packets
with one "tag", and not others on an output port?
(There could be some merit in multicast?)


> Second, if we have two SNDUs with differents destinations, we can't put
> them or their fragments in
> the same mpeg2-tp, or we need a label for each fragment added to the
> pointer which is specified in the last draft.
> 

You're talking about the shared-PID switched case above, yes?

OK, you can place each SNDU in a separate TS-packet.
That's not ILLEGAL in the new encapsulation, and, I guess you
would be free to define your own encapsulation / adaptation header
to carry any extra tags...

BUT, by default, the design assumes you WILL pack SNDUs, or at least
the encapsulating gateway device MAY choose to do so, on a per-SNDU
basis.

> Aniba.
> 
> --
> Ghassane ANIBA
> INRIA (Projet PLANETE)             | Email :
> ghassane.aniba@sophia.inria.fr
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