Re: MPE Question

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

See a few in-line comments.

On 28/4/05 2:42 pm, "Summers Edwin" <summers_edwin@bah.com> wrote:

> Greetings,
> 
> While researching MPE and the proposed ULE spec, I ran across some
> information that I cannot equate.
> 
> If I read table 3 of EN 301 193 v1.4.1 (DVB spec for data broadcasting)
> correctly, the overhead of an MPE section is 16 bytes (assuming LLC/SNAP
> not used). 
OK.
> But while researching MPE I found a brief by Vladimir
> Ksinant, Alain Ritoux, and "fritsche" entitled "Using ULE for IPv4/v6 in
> MPEG-2 encapsulation" (12/11/2003) that states there is 17 bytes of
Including the Payload Pointer (PP), perhaps?
- See the examples of using the PP in TS Packets at the end of the ULE Spec.

> header/trailer for IPv4 packets encapsulated by MPE, and 25 bytes for
> IPv6, assuming use of LLC/SNAP.
> 
> 1) For a section encapsulating an IPv4 packet and not using LLC/SNAP, is
> the overhead 16 or 17 bytes? (same for ULE...I count 8 bytes in
> draft-ietf-ipdvb-ule-05 section 4 where the above document states 9
> bytes, when not using the destination address)
> 
I guess also considering the  overhead of the PP byte?

> 2) (for MPE) If my original calculation of 16 bytes is correct, then
> would the overhead for a section using LLC/SNAP be 24 bytes (16 + 8 byte
> LLC/SNAP)?
> 
> 3) Do current MPE implementations in IPv6 networks require the use of
> LLC/SNAP in the section?  I know this was discussed on the list some
> time ago, and I believe the reason for it was because MPE does not
> include a type field, where ULE does.  Are there any current MPE
> implementations that do not require LLC/SNAP for IPv6 packets?
> 
> Thanks in advance!
> Ed
> 
> --------------------
> Ed Summers
> Booz Allen Hamilton
> (o) 703.377.1407
> (f) 703.902.3409
> 
>