Dear colleagues,
Alcatel Space Industries would like to support the work currently undertaken by
this group.
As requested by Gorry Fairhurst, here follows a draft of the presentation we
could make at the next BOF :
(See attached file: Alcatel_space_IP_DVB_view01.pdf)
Note that this document is informational only but can be distributed freely to
anybody interested.
The general issues raised here seem to align with those expressed in
http://www.erg.abdn.ac.uk/users/gorry/ip-dvb/charter.html and
http://www.erg.abdn.ac.uk/users/gorry/ip-dvb/ids/draft-fair-ipdvb-req-00.doc
It includes our vision for MPE enhancement. We would actually be very interested
if the to-be-defined encapsulation could support protocols other than IPv4 and
v6. Ethernet and MPLS are of equal importance according to the network segment
the DVB (or other MPEG-2 based) links are deployed. It would be nice if a future
RFC could have the same role than ITU-T I.363.5 (AAL5) and RFC-2684
(Multiprotocol encapsulation) have in the ATM world.
It also details some Layer 2 labelling management procedures that we have
developed in the frame of the BRAHMS IST project. This is perhaps more targetted
to a MPE "replacement". It actually includes a label distribution protocol
(working in a similar way as Ethernet ARP) and associated encapsulation
optimised for the broadcast nature of satellites (and thefore DVB) links. Such
kind of protocol could well play for broadcast links the same role than MPLS in
backbone networks.
The main ideas behind this proposed scheme are in line with the questions about
a possible "native IP" support that Gorry raised in his 03/25 e-mail. PID would
indeed only be a first level of filtering at receivers. IP filtering would then
be based on IP destination address. An additional label at layer 2, identifying
the source of the IP flow, could help avoiding to re-assemble all the IP traffic
received on a given PID (and allow proper re-assembly if packets are mixed by a
satellite on-board processor). Therefore a limited link layer header might still
be useful. The other characteristics of our scheme is that it naturally supports
multiple feeds configurations, two-way satellite links and on-board processing
(no more multisource multicast headaches !)
You'll find more details about BRAHMS project at
http://brahms.telecomitalialab.com/. There was also a paper published at last
year's AIAA conference ("IP Dedicated : a new Internet oriented satellite
transfer scheme", I. Buret et al., 19th AIAA ICSSC conference, april 2001).
Note that some outputs of the BRAHMS project have already been presented at the
ETSI BSM. Actually, the same presentation which is included here is being sent
to the ETSI BSM mailing-list.
Feel free to share comments on this list,
Best Regards,
Stéphane COMBES
ALCATEL SPACE INDUSTRIES
Research Department/Advanced Telecom Satellite Systems
Tel : +33 (0)53435 6938 / Fax : +33 (0)53435 5560
Porte : F1027 / E-Mail : stephane.combes@space.alcatel.fr
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