Minutes of 2nd Open IP-DVB Meeting (IP over MPEG-2 Transport)

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

Minutes of 2nd Open IP-DVB Meeting (IP over MPEG-2 Transport)
14:00 Monday, 24th June
Hosted by Alcatel Space Industries, Toulouse, France

Agenda

5 minutes:      Agenda bashing
5 minutes:      Working Group Status
15 minutes:     Review charter
http://www.erg.abdn.ac.uk/users/gorry/ip-dvb/charter.html

Review of current IDs
20 minutes:     draft-fair-ipdvb-req-01.txt
20 minutes:     draft-unisal-ipdvb-enc-00.txt
20 minutes:     Other needed IDs
Break 
5 minutes:      Attendance at IETF
10 minutes:     Links with other WGs
10 minutes:     Timeline

---------------

Stephane Combes started the meeting with a welcome to ASPI Toulouse. Gorry
Fairhurst and Marie-Jose Montpetit chaired the meeting.

There were no new agenda items, but Stephane Combes was asked  to start with
the first presentation to allow time to prepare the other presentations.

Presentation of Alcatel Space Industries (ASPI) activities
==========================================================

Stephane Combes provided a presentation of a range of Alcatel Space
Industries (ASPI) activities relating to Internet service provision via
satellite using DVB-based systems.

This showed the perceived need for two work in two areas:

MPE enhancement (short term)

He noted the issue of no MAC-level source address in the basic MPE
encapsulation. This raised issues for multicast encpasulation when there
were several sources.

There was also interest from ISPs in MPEG-2 delivery of an Ethernet Like
layer (in the manner of ADSL).  MPLS and PPoE options were also being
investigated.

MPE replacement (long term)

Longer-term he saw a need for a dynamic address resolution process, and
better support for multicast. Security issues also needed to be addressed.


Some work had already been done by ASPI on MPE replacement, defining a
protocol called IP-Dedicated. This was aimed at two-way DVB-RCS based
satellite systems. One key feature of this work was the use of L3 filters
(i.e., internet address filters in the receivers), but he concluded a simple
level 2 filter was also desirable to reduce layer 3 processing. This would
also allow virtual subnetworks to be configured and to lead to future L2
switching within a DVB multiplexor (or DVB-capable on-board processing
satellite).

He described two current projects looking at IP over MPEG-2 transmission
that have been funded by the European Commission (IST-Brahms, IST-SATIP6).

Longer-term he saw the need to improve IPv6 support. Some ASPI work had some
associated IPR. It was thought that the ip-dvb activity would complement
this work, and ASPI would like to support it.

REVIEW OF CHARTER
=================

Gorry presented a status report for the ip-dvb activity. This covered,
liasons with DVB, the desired work of the group, and the charter.

Marie-Jose suggested that a short one page summary document should be
prepared to position the work clearly.  This could be used as a marketing
document for briefing DVB equipment manufacturers on the proposed new
protocol stack. When asked, she agreed to draft this document for the
mailing list.

No new items were suggested for the charter.

REVIEW OF IDS
=============

Gorry Fairhurst presented the status of the two IDs (no other authors were
present). 
 
REQUIREMENTS (draft-fair-ipdvb-req-01.txt)

The requirements draft had recently been updated to -01, to include
rationale for signalling following the combined meeting with DVB-GBS.  This
DVB working group had produced an DVB draft for signalling (INT). This would
be based on DVB SI signalling tables. A new version of the INT document was
in preparation, status was not known. Diagrams had also been added, to the
-01 draft. Gorry asked for corrections / comments.

One issue raised by the DVB INT draft was the need for ³platform ids² to
describe the scope of the addresses being advertised.  A single MPEG-2 TS
logical channel could be used to address several virtual private networks,
each with overlapping address space, and uniquely identified by MAC address
and platform ID.  Was this a good idea? There was some discussion of whether
this approach was suited to more general Interent needs. No conclusion.

ENCAPSULATION (draft-unisal-ipdvb-enc-00.txt)

The encapsulation draft was presented and a discussion followed. Patrick
Cipiere asked why there was no MAC address in the basic header format, only
as an extension header?

Since MPE included a destination MAC address, some suggested that L2
addresses should at least be part of the basic encapsulation.

There was discussion about the possibility of using the most significant
bits of the length field to hold two flag bits (as originally suggested by
Patrick on the mailing list). One signalling bit could indicate presence of
a MAC source address, another a MAC destination address. This also seemed to
have the advantage that a 01 setting would be backwards compatible with MPE,
and 00 would be equivalent to the current proposal (-00).

Marie-Jose asked when a MAC address was actually required.... This should
be documented.

If we proceede with this - we would need to find space for the signalling
bits in the fixed header. Two places were possible, one in the length field
and one in the type field.  Do we need to support packets greater than 16
KB?  

When this had previously been posted as a proposal to the list it had
received little comment. It was agreed to take this to the list again, in
time for the next rev of the draft.

Gorry said the current case for using the AFC bits  in the MPEG-2 TS Packet
header was not well stated at the moment. This should be updated in the next
draft.

ADDRESS RESOLUTION

Gorry Fairhurst  suggested there was now a need for an ID from the ip-dvb
activity to clarify how address resolution could work.

IPv6
====

Marie-Jose presented a set of slides on IPv6 and looked at RFC2461 and
RDISC.  The meeting concluded that some attention should be paid to router
and neighbourhood discovery when looking at addrress resolution for IPv6. A
critical look at multi-homing may also be appropriate for home scenarios
were DVB and other broadband services may all  be present.

IP-CC
=====

Pekka (Nokia) presented a set of slides on the proposed role of IP-CC for
service discovery.  This draft proposal had previously been presented at
DVB-GBS working group, and was intended to provide service discovery.  The
current proposal was aimed at DVB-T (terrestrial) TV networks supporting IP
services.  There were similarities to the way SAP  is used in current IP
multicast networks, but a broader scope was envisaged for the new protocol.
One key issue was to provide mechanisms for location-based delivery, in
which the service was associated with a geographical region.

The proposal seemed to be complimentary to the proposed work on IP over
MPEG-2.  It was discussed whether this work was  within the charter of the
ip-dvb activity - or whether it should be placed with another working group.
Since it was not within the current charter, there was no decision to
progress with this within the group.


CONCLUSIONS
=============

There was discussion of the possibility of developing some reference
implementations to allow experimentation with the new encapsulation. Frank
Zeppenfeldt from the European Space Agency said they would be interested in
receiving project ideas associated with implementation of the new
encapsulation (and possibly other protocol components).

The meeting agreed that more work was required to understand exactly what
was being proposed before we were ready to bring this to the IETF, but that
considerable progress had been made and that there was a clear enthusiasm to
proceed. Would we be ready for October?

Gorry agreed to contact the appropriate IESG Area Directors to ask about the
possibility of a BoF in Atlanta.  He would also contact the DVB-GBS WG chair
to find out progress with their signalling work.

The circulated attendance sheet showed 14 people were present. Thanks to
Stephane Combes for arranging lunch and for the good local organisation of
this meeting.