Re: Remarks concerning IP-over-DVB

[Patrick Cipiere <Patrick.Cipiere@udcast.com>]

Torsten.Jaekel@FTK.rohde-schwarz.com wrote:

> Imagine we transmit each IP connection in a dedicated DVB sub-channel,
> given by the PID

We only have 8191 PIDs, and in some cases like Eutelsat Skyplex, or
TDMA access, this number might be reduced to less than a hundred.
So the number of available PIDs might be an issue.

This might also raise some issues from the manufacturers. Currently
most of the cards do hardware filtering on only from 8 to 32 PIDs
simultaneously.
I am also using cards that do not hardware filter the PIDs, but leave
this task to the driver. With these  cards it is easier to deal with the
whole 8191 PIDs, but cost more cpu cycles.

I guess that some questions we will have to discuss on this
mailing-list are about layering:
- what is our layer 1?
  for me: it is MPEG2 TP (included) and under.
  it even can be MPE (included) and under.

Of course considering MPE as the layer 1 you need to encapsulate the
layer 2 (ethernet for example) using LLC_SNAP and RFC1483 with either
- Ethertype 0x6558 `transparent ethernet bridging'
- Bridged Ethernet/802.3
This is will add some extra bytes and therefore waste some bandwith,
but we get something that we might consider as a valuable information
with the IEEE 48 bits source MAC address (which is not in the MPE
datagram section).

Patrick.
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