>- What about special satellite-specific link layers? Are MPEG frames
>carried inside these L2 protocols?
No - MPEG system layer for transport steam does this job for you.
(Reference - ISO/IEC 13818-1)
Regarding other Qs:
The DVB standard defines 5 different data broadcasting profiles (as listed
below) over DVB compliant broadcast networks. Each profile is defined for a
different application area.
Data Piping (data is carried directly in the payloads of MPEG-2)
Data Streaming (data is carried in PES packets defend in MPEG-2)
Multiprotocol Encapsulation (data is encapsulated in DSM-CC sections, which
are compliant with the MPEG-2 private section format)
Data Carousels (data is transmitted in a DSM-CC data carousel as defend in
MPEG-2)
Object Carousels (data is transmitted according to the DSM-CC object and
data carousel specifications as defend in MPEG-2).
The data broadcast specification profile for multiprotocol encapsulation
(third in the list) supports data broadcast service that requires the
transmission of communication protocol datagrams over DVB networks. If the
LLC_SNAP_flag is set the payload carries LLC/SNAP encapsulated datagrams,
following the MAC_address_1 field. When it carries an IP datagram directly,
the LLC_SNAP_flag is set zero. The fragmentation and reassembling service
is provided using the section length, section number and last section
number. For example, the section number indicates the fragment number, if
the datagram has been fragmented. The Medium Access Control (MAC) address
(e.g., Ethernet address) of the destination device will be encapsulated
using the MAC address fields.
The multi-protocol encapsulation profile is becoming an open standard within
industry, although other data broadcasting profiles have also implemented by
some manufactures
In a simple configuration of a satellite-based DVB network, a low cost
receive only satellite terminal may be used to construct a cost-effective
high speed simplex distribution. The server transfers the data to the client
through the higher speed satellite link. A client networking device (the
client computer itself or the router) has two network interfaces; one
connected to the receive DVB link and the other connected by an Internet
Service Provider to the terrestrial network. The hub router forwards data
through the satellite network while the return data may be sent through the
terrestrial - ISDN, ADSL, dialup links (or in future using a low power
satellite return link - see new Astra work).
Reference:
'Digital Video Broadcasting (DVB) specification for data broadcasting',
ETSI, Draft EN 301 192 V1.1.1 (1997-08), 1997.
N. Samaraweera and G. Fairhurst, 'High Speed Internet Access Using
Satellite-Based DVB Networks', International Network Conference (INC'98),
IEE, Plymouth, UK, 23-28 (1998).
http://www.erg.abdn.ac.uk/publications.html + more publications
A. N.K.G. Samaraweera, "Return Link Optimisation for Internet Service
Provision Using DVB-S Networks", in Computer Communication Review, a
publication of ACM SIGCOMM, volume 29, number 3, July 1999.
http://www.acm.org/sigcomm/ccr/archive/1999/jul99/ccr-9907-samaraweera4.html
-----Original Message-----
From: Chris Metz [mailto:[email protected]]
Sent: 06 June 2000 3:27 AM
To: [email protected]
Subject: IP over Satellite Questions/References
Hi-
Based on a reference to Dish Network and Gilat I heard the other day on
CNBC I am suddenly very curious about the use of satellite for broadband
access to the home or business and IP over Satellite in general. As a
generalization of the TCP over satellite problems and solutions that have
been well documented over the last few years I was wondering about the
following:
- IP/MPEG/DVB? So are IP packets carried in the MPE capabilities of MPEG
for transmission over DVB systems?
- What about special satellite-specific link layers? Are MPEG frames
carried inside these L2 protocols?
- How is the satellite uplink for a bidirectional system done? I am
familiar with the DirecPC approach of using a terrestrial (dial, ISDN)
uplink from the home. Is the bandwidth symmetrical or asymmetrical?
- How much bandwidth is possible? I see that DirecPC advertises 400Kb. What
are the issues that affect how much bandwidth one can use?
Any conferences/tutorials/whitepapers/books that people can recommend to
learn about this stuff?
Thanks ...
Chris Metz
Lead IP Architect
Solutions Integration
Service Provider Line of Business
Cisco Systems
email: [email protected]
offic phone: 408-525-3275
home office: 914-241-0423
pager: 800-365-4578
Internal URL: http://wwwin-people.cisco.com/chmetz/chmetz.htm
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