RE: MPE Question

["Simon Teh" <chteh@nrg.cs.usm.my>]

Dear members,

I have gone through the document that mention by Ed Summers, for my opinion
the authors had included the Payload Pointer in the overhead bytes
calculation for MPE and ULE.

Normally when we calculate the encapsulated bytes MPEG-2 TS for MPE and ULE:

If the payload unit is a new payload, usually we calculated in this way =
Encapsulated bytes =188bytes   - 4bytes    -  1 bytes
                 (TS pkt size)  (TS header)   (PP)
Encapsulated bytes = 183 

So I think maybe the authors had considered the overhead of PP (like what
Gorry said)

Best Regards,
Simon Teh
Universiti Sains Malaysia

-----Original Message-----
From: owner-ipdvb@erg.abdn.ac.uk [mailto:owner-ipdvb@erg.abdn.ac.uk] On
Behalf Of Summers Edwin
Sent: 28 April 2005 21:42
To: ipdvb@erg.abdn.ac.uk
Subject: RE: MPE Question

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).  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
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) 

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