Internet Engineering Task Force Gorry Fairhurst
Internet Draft University of Aberdeen
Expires July 2007 B. Collini-Nocker
University of Salzburg
Category: WG Draft intended for PS March 2007
Extension Formats for Unidirectional Link Encapsulation (ULE)
and the Generic Stream Encapsulation (GSE)
draft-ietf-ipdvb-ule-ext-01.txt
Status of this Draft
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Abstract
This document describes a set of Extension Headers for the
Unidirectional Link Encapsulation (ULE) [RFC4236].
The Extension Header formats defined in this document define new
extensions that are common extensions to both ULE and the Generic
Stream Encapsulation (GSE) [GSE] defined by the second generation
framing structure DVB-S2 standard [S2].
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Table of Contents
1. Introduction
2. Conventions used in this document
3. Description of method
3.1 MPEG-2 TS-Concat Extension
3.2 PDU-Concat Extension
3.3 TimeStamp Extension
4. Summary
5. IANA Considerations
6. Acknowledgments
7. Security Considerations
8. References
8.1 Normative References
8.2 Informative References
9. Authors' Addresses
10. IPR Notices
10.1 Intellectual Property Statement
10.2 Disclaimer of Validity
11. Copyright Statement
11.1 Intellectual Property Statement
11.2 Disclaimer of Validity
Appendix A:
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1. Introduction
This document describes two new Header Extensions that may be used
with both Unidirectional Link Encapsulation, ULE, [RFC4236] and the
Generic Stream Encapsulation (GSE) [GSE]. ULE is defined for links
that employ the MPEG-2 Transport Stream, and supports a wide variety
of physical-layer bearers [RFC4259].
GSE has been designed for the Generic Mode (also known as the
Generic Stream (GS)), offered by second-generation DVB physical
layers, and specifically for DVB-S2 [ETSI-S2]. The requirements for
the Generic Stream are defined in [S2-REQ], [S2-REQ-RCS], and [ID-
S2-REQ]. The important characteristics of this encapsulation are
described in an Appendix to this document. GSE maintains a design
philosophy that presents a common network interface to that of ULE
and uses a similar construction for Subnetwork Data Unit (SNDUs).
One extension header defines a method that allows one or more TS-
Packets [ISO-MPEG] to be sent within a ULE SNDU. This method may be
used to provide control plane information including the transmission
of MPEG-2 Program Specific Information (PSI) for the Multiplex. In
GSE, there is no native support for transport stream packets and
this method is therefore suitable for providing an MPEG-2 control
plane.
A second extension header allows one or more PDUs to be sent within
the same ULE SNDU. This method is designed for cases where a large
number of small PDUs are directed to the same Network Point of
Attachment (NPA) address. The method may improve transmission
efficiency (by removing duplicated MAC layer overhead). It can also
reduce processing overhead for receivers that are not addressed by
the NPA, since these receivers may then skip several PDUs in one
operation. The method is defined as a generic extension header and
may be used for IPv4 or IPv6 packets. If and when a compression
format is defined for ULE or Ethernet, the method may also be used
in combination with this method.
A third extension header provides an optional timestamp value for an
SNDU. Examples of the use of this timestamp option include
monitoring and benchmarking of ULE and GSE links. Receivers that do
not wish to decode (or do not support) the timestamp extension may
discard the extension and process the remaining PDU or extension
headers.
The appendix includes a summary of key design issues and
considerations based on the GSE Specification defined by the DVB
Technical Module [GSE].
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2. Conventions used in this document
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL",
"SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in
RFC 2119 [RFC2119].
b: bit. For example, one byte consists of 8b.
B: Byte. Groups of bytes are represented in Internet byte order.
BBFrame payload [ETSI-S2]: The data field part of a Baseband frame
that may be used for the communication of data. Typical BBFrames
range in size from 3072 to 58192 bits according to the choice of
modulation format and FEC in use.
DVB: Digital Video Broadcast. A framework and set of
associated standards published by the European Telecommunications
Standards Institute (ETSI) for the transmission of video, audio, and
data.
Encapsulator: A network device that receives PDUs and formats these
into Payload Units (known here as SNDUs) for output in DVB-S or the
Generic Mode of DVB-S2.
GS: Generic Stream [S2].
GSE: Generic Stream Encapsulation [GSE].
MAC: Medium Access Control [IEEE-802.3]. A link layer protocol
defined by the IEEE 802.3 standard (or by Ethernet v2).
MPEG-2: A set of standards specified by the Motion Picture Experts
Group (MPEG), and standardized by the International Standards
Organisation (ISO/IEC 113818-1) [ISO-MPEG], and ITU-T (in H.220).
Next-Header: A Type value indicating an Extension Header [RFC4236].
NPA: Network Point of Attachment [RFC4236]. In this document, refers
to a destination address (resembling an IEEE MAC address) within the
DVB-S/S2 transmission network that is used to identify individual
Receivers or groups of Receivers.
PDU: Protocol Data Unit [RFC4259]. Examples of a PDU include
Ethernet frames, IPv4 or IPv6 datagrams, and other network packets.
PSI: Program Specific Information [ISO-MPEG].
SI Table: Service Information Table [ISO-MPEG]. In this document,
this term describes a table that is been defined by another
standards body to convey information about the services carried on a
DVB carrier.
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SNDU: Subnetwork Data Unit [RFC4259]. In this document this is an
encapsulated PDU sent using ULE or GSE.
Stream: A logical flow from an Encapsulator to a set of Receivers. .
TS: Transport Stream [ISO-MPEG], a method of transmission at the
MPEG-2 level using TS Packets; it represents layer 2 of the ISO/OSI
reference model.
ULE: Unidirectional Link Encapsulation (ULE) [RFC4236]. A scheme
that encapsulates PDUs, into SNDUs that are sent in a series of TS
Packets using a single TS Logical Channel. The encapsulation format
defined by this document shares the same extension format, and basic
processing rules and uses a common IANA Registry.
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3. Description of the Method
In ULE, a Type field value that is less than 1536 Decimal indicates
an Extension Header. This section describes a set of two extension
formats for the ULE encapsulation. The GSE specification is defined
in [GSE] and follows these formats, but as in other SNDU formats,
GSE does not include a per-SNDU CRC and utilises a different SNDU
length calculation [GSE].
3.1 MPEG-2 TS-Concat Extension
>>> IANA Action required, please replace < #NH-TS-CAT> with assigned
value from the Next-Header Registry>>>
The MPEG-2 TS-Concat Extension Header is specified by an IANA
assigned H-Type value of <#NH-TS-CAT>. This is a Mandatory Next-
Header Extension.
The extension is used to transport 1 or more MPEG-2 TS Packets
within a ULE SNDU. The number of TS Packets carried in a specific
SNDU is determined from the size specified by the remainder of the
Payload following the MPEG-2 TS Extension. The number of TS packets
contained in the SNDU is therefore (Length-N-10+D*6) / 188, where N
is the number of bytes associated with Extension Headers that
precede the MPEG-2 TS-Concat Extension (zero if there are none). A
Receiver MUST check that the payload length is correct prior to
processing it. Any mismatch (remainder from the division) MUST
result in discard of all encapsulated PDUs and SHOULD be recorded as
TS-concat size mismatch error.
A value D=0 indicates the presence of a NPA address. In that case
the correct payload length for ULE is (Length-10) / 188, whereas in
case of GSE the correct payload length is (Length-6) / 188.
>>> IANA Action required, please replace < #NH-TS-CAT> with assigned
value from the Next-Header Registry>>>
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0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Length (15b) | Type = 0x <#NH-TS-CAT> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiver Destination NPA Address (6B) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| TS-Packet 1 |
= =
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TS-Packet 2 (if Length > 2*188) |
= =
| etc. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 1: ULE/SNDU Format for a TS-Packet Payload (D=0)
>>> IANA Action required, please replace <#NH-TS-CAT> with assigned
value from the Next-Header Registry>>>
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| Length (15b) | Type =0x <#NH-TS-CAT> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiver Destination NPA Address (6B) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ |
| TS-Packet 1 |
= =
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TS-Packet 2 (if Length > 2*188) |
= =
| etc. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: GSE/SNDU Format for a TS-Packet Payload (D=0)
Note that fragmented GSE SNDUs are protected by a CRC-32 carried in
the final fragment, and that non-fragmented GSE SNDUs are protected
by a CRC-32 in the final bytes of the GS DataField.
A value of D=1, is also permitted and indicates the absence of a NPA
address, as defined in ULE. A similar format is supported in GSE.
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>>> IANA Action required, please replace <#NH-TS-CAT> with assigned
value from the Next-Header Registry>>>
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Length (15b) | Type = 0x<#NH-TS-CAT> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TS-Packet 1 |
= =
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| TS-Packet 2 (if Length > 2*188) |
= =
| etc. |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: ULE/SNDU Format for a TS-Packet Payload (D=1)
The extension may be used to transport one or more MPEG-2 TS Packets
of arbitrary content, interpreted according to [ISO-MPEG]. One
expected use is for the transmission of MPEG-2 SI/PSI signalling.
The use of this format to transfer MPEG-2 clock references (e.g. a
Network Clock Reference, NCR, SI Table) over ULE/GSE framing raises
timing considerations at the encapsulation gateway, including the
need to update/modify the timing information prior to transmission
by the physical layer. These issues are not considered here, but it
is noted that the operation may be simplified by ensuring that all
SNDUs that carry this Extension Header are placed before other data
within the GSE DataField [GSE].
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3.2 PDU-Concat Extension
>>> IANA Action required, please replace <#NH-PDU-CAT> with assigned
value from the Next-Header Registry>>>
The PDU-Concat Extension is specified by an IANA assigned H-Type
value of <#NH-PDU-CAT> This is a Mandatory Next-Header Extension.
It enables a sequence of (usually short) PDUs to be sent within a
single SNDU payload.
The base header contains the Length of the entire SNDU. This carries
the value of the combined length of all PDUs to be encapsulated,
including each set of encapsulation headers. The base header also
caries a 16-bit ULE Type field. Although any Type value specified in
the ULE Next-Header Registry may be assigned to the encapsulated
PDU, all PDUs included in the SNDU payload MUST have a common ULE
Type (i.e. all concatenated PDUs passed by the network layer must be
associated with the same Type value). This simplifies the receiver
design, and reduces the transmission overhead for common use cases.
Each PDU is prefixed by its length in bytes (shown as PDU-Length in
the following diagrams). Encapsulated PDUs are of arbitrary length
(in bytes) and are not necessarily aligned to 16-bit or 32-bit
boundaries within the SNDU (as shown in the figure). The most
significant bit of the first byte MUST be set to zero. The length of
each PDU MUST be less than 32 758 bytes, but will generally be much
smaller.
When the SNDU header indicates the presence of an SNDU Destination
Address field (i.e. D=0), a Network Point of Attachment, NPA, field
directly follows the fourth byte of the SNDU header. NPA destination
addresses are 6 Byte numbers, normally expressed in hexadecimal,
used to identify the Receiver(s) in a transmission network that
should process a received SNDU. When present the Receiver MUST
associate the same specified MAC/NPA address with all PDUs within
the SNDU Payload. This MAC/NPA address MUST also be forwarded with
each PDU, if required by the forwarding interface.
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>>> IANA Action required, please replace <#NH-PDU-CAT> with assigned
value from the Next-Header Registry in the next two figures>>>
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Length (15b) | Type = 0x<#NH-PDU-CAT> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiver Destination NPA Address (6B) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | CONCAT-PDU-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| PDU-Length-1 (15b) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
= PDU-1 =
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| PDU-Length-2 (15b) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
= PDU-2 =
| |
More PDUs as required
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: ULE/SNDU Format for a PDU-Concat Payload (D=0)
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Length (15b) | Type = 0x<#NH-PDU-CAT> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiver Destination NPA Address (6B) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | CONCAT-PDU-Type |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| PDU-Length-1 (15b) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
= PDU-1 =
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| PDU-Length-2 (15b) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
= PDU-2 =
| |
More PDUs as required
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
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Figure 5: GSE/SNDU Format for a PDU-Concat Payload (D=0)
A value of D=1 indicates there is no NPA/MAC address in use. This
field MUST be carried (i.e. D=0) for IP unicast packets destined to
routers that are sent using shared links (i.e., where the same link
connects multiple Receivers). A sender MAY omit this field (D=1) for
a set of packets delivered to a Receiver or group of receivers that
are able to utilise a discriminator field (e.g. the IPv4/IPv6
destination address, or a bridged MAC destination address), which in
combination with the PID value, could be interpreted as a Link-Level
address. A similar format is supported in GSE.
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| Length (15b) | Type = 0x<#NH-PDU-CAT> |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| CONCAT-PDU-Type |0| PDU-Length-1 (15b) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
= PDU-1 =
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|0| PDU-Length-2 (15b) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
= PDU-2 =
| |
More PDUs as required
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: ULE/SNDU Format for a PDU-Concat Payload (D=1)
The Receiver processes this Extension Header by verifying that it
supports the specified CONCAT-PDU Type (unsupported Types MUST be
discarded but the receiver SHOULD record a PDU-Type error). It then
extracts each encapsulated PDU in turn. The Receiver MUST verify the
Length of each PDU. It MUST also ensure the sum of the Lengths of
all processed PDUs is less than the Length specified in the SNDU
base header. A Receiver MUST discard the whole SNDU if the sizes do
not match and this event SHOULD be recorded as a PDU-concat size
mismatch error.
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3.3 Timestamp Extension
The timestamp extension header permits an Encapsulator to add a
timestamp field to an SNDU. This is designed to support monitoring
and measurement of ULE performance over a link to indicate the
quality of an operational ULE link. This may be useful for GSE links
(where significant complexity exists in the scheduling provided by
the lower layers). This extension may be (optionally) checked at the
Receiver.
Possible uses of this extension include:
* Validation of in-sequence ordering per Logical Channel,
* Measurement of one-way delay (when synchronised with the sender)
* Measurement of PDU Jitter introduced by the link,
* PDU loss (with additional information from the sender).
>>> IANA please insert a value for the H-Type from the Optional part
of the Next-Header Registry, and replace <NH-TStamp> in the sentence
below, and the figure following <<<
The Timestamp Extension Header is specified by the IANA-assigned H-
Type of <NH-TStamp>. This extension is an Optional Extension Header
([RFC4326], Section 5).
0 7 15 23 31
+---------------+---------------+---------------+---------------+
| 0x03 | <NH-TStamp> | time stamp HI |
+---------------+---------------+---------------+---------------+
| time stamp LO | Type |
+---------------+---------------+---------------+---------------+
Figure 7 The format of the 32-bit Timestamp Extension Header
Figure 7 shows the format of this extension with a HLEN value of 3
indicating a timestamp of length 4B with a Type field (there is no
implied byte-alignment).
The extension carries a 32-bit value (time stamp HI plus time stamp
LO). The specified resolution is 1 microsecond. The value therefore
indicates the number of 1 microsecond ticks past the hour in
Universal Time when the timestamp option was inserted, right-
justified to the 32-bit field. Systems unable to insert timestamps
at the specified resolution may use an arbitrary (and varying) value
to pad the unused least-significant bits.
The last two bytes carry a 16-bit Type field that indicates the type
of payload carried in the SNDU, or the presence of a further Next-
Header ([RFC4326], Section 4.4).
This is an Optional Extension Header. Receivers that do not
implement, or do not wish to process, the Timestamp Extension MAY
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skip this extension and continue to process the remainder of the
SNDU, forwarding the encapsulated PDU.
4. Summary
This document defines a set of Next_Header Extensions for the
Unidirectional Link Encapsulation (ULE).
5. IANA Considerations
This document requires IANA involvement for the assignment of two
new Next-Header Type values from the IANA ULE Next-Header Registry.
These options are defined for specific use cases envisaged by GSE,
but are compatible with ULE.
The TS-Concat Extension is a Mandatory next-type extension header,
specified in section 3.1 of this document. The value of this next-
header is defined by an IANA assigned H-Type value of <#NH-TS-CAT>.
The PDU-Concat Extension is a Mandatory next-type extension header
specified in section 3.2 of this document. The value of this next-
header is defined by an IANA assigned H-Type value of <#NH-PDU-CAT>.
The Timestamp Extension is an Optional next-type extension header
specified in section 3.3 of this document. The value of this next-
header is defined by an IANA assigned H-Type value of <#NH-TStamp>.
This documents defines format for a HLEN value of 0x3.
6. Acknowledgments
The author gratefully acknowledges the inputs, comments and
assistance offered by the members of the DVB-GBS ad hoc group on S2
encapsulation, in particular contributions on transmission aspects
from Rita Rinaldo, Axel Jahn, and Ulrik De Bie.
7. Security Considerations
No specific security issues are raised within this document.
Additional security control fields may be provided as a part of a
link encryption Extension Header, e.g. to associate a PFU with one
of a set of Security Association (SA) parameters. As a part of the
encryption process, it may also be desirable to authenticate
some/all of the headers. The method of encryption and the way in
which keys are exchanged is beyond the scope of this specification,
as also are the definition of the SA format and that of the related
encryption keys.
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8. References
8.1 Normative References
[RFC2119] Bradner, S., "Key Words for Use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, 1997.
[RFC4236] Fairhurst, G. and B. Collini-Nocker, "Unidirectional
Link Encapsulation (ULE) for transmission of IP datagrams over an
MPEG-2 Transport Stream", RFC 4236, December 2006.
8.2 Informative References
[ETSI-DAT] EN 301 192, "Specifications for Data Broadcasting",
European Telecommunications Standards Institute (ETSI).
[ETSI-S2] EN 302 307, "Digital Video Broadcasting (DVB); Second
generation framing structure, channel coding and modulation systems
for Broadcasting, Interactive Services, News Gathering and other
broadband satellite applications", European Telecommunication
Standards Institute (ETSI).
[GSE] "Generic Stream Encapsulation", Work in Progress, DVB
Technical Module (GBS Group), 2006.
[ID-S2-REQ] "Requirements for transmission of IP datagrams over DVB-
S2", Internet Draft <draft-cantillo-ipdvb-s2encaps-01.rxr>, Work in
Progress.
[ISO-MPEG] ISO/IEC DIS 13818-1:2000, "Information Technology;
Generic Coding of Moving Pictures and Associated Audio Information
Systems", International Standards Organisation (ISO).
[RFC4259] Montpetit, M.-J., Fairhurst, G., Clausen, H., Collini-
Nocker, B., and H. Linder, "A Framework for Transmission of IP
Datagrams over MPEG-2 Networks", RFC 4259, November 2006.
[S2] EN 302 307, "Digital Video Broadcasting (DVB); Second
generation framing structure, channel coding and modulation systems
for Broadcasting, Interactive Services, News Gathering and other
broadband satellite applications", European Telecommunication
Standards Institute (ETSI).
[S2-REQ] GBS0339, "Functional and performance requirements for
IP/S2", DVB-TM (GBS WG).
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[S2-REQ-RCS] "Requirements for S2", Document 529r1, DVB Technical
Module (RCS WG).
9. Authors' Addresses
Godred Fairhurst
Department of Engineering
University of Aberdeen
Aberdeen, AB24 3UE
UK
Email: gorry@erg.abdn.ac.uk
Web: http://www.erg.abdn.ac.uk/users/Gorry
Bernhard Collini-Nocker
Department of Computer Sciences
University of Salzburg
Jakob Haringer Str. 2
5020 Salzburg
Austria
EMail: bnocker@cosy.sbg.ac.at
Web: http://www.cosy.sbg.ac.at/
10. IPR Notices
10.1 Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology described
in this document or the extent to which any license under such
rights might or might not be available; nor does it represent that
it has made any independent effort to identify any such rights.
Information on the procedures with respect to rights in RFC
documents can be found in BCP 78 and BCP 79.
Copies of IPR disclosures made to the IETF Secretariat and any
assurances of licenses to be made available, or the result of an
attempt made to obtain a general license or permission for the use
of such proprietary rights by implementers or users of this
specification can be obtained from the IETF on-line IPR repository
at http://www.ietf.org/ipr.
The IETF invites any interested party to bring to its attention any
copyrights, patents or patent applications, or other proprietary
rights that may cover technology that may be required to implement
this standard. Please address the information to the IETF at ietf-
ipr@ietf.org.
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10.2 Disclaimer of Validity
This document and the information contained herein are provided on
an "AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE
REPRESENTS OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE
IETF TRUST AND THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL
WARRANTIES, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY
WARRANTY THAT THE USE OF THE INFORMATION HEREIN WILL NOT INFRINGE
ANY RIGHTS OR ANY IMPLIED WARRANTIES OF MERCHANTABILITY OR FITNESS
FOR A PARTICULAR PURPOSE.
11. Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
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APPENDIX: DVB-S.2
PDUs, (Ethernet Frames, IP datagrams or other network layer packets)
are encapsulated to form a Subnetwork Data Unit (SNDU) [RFC4236]
associated with a specific Stream at the link layer. The SNDU is
transmitted over an DVB-S2 link by placing it either in a single
BBFrame, or if required, an SNDU may be fragmented into a series of
BBFrames [ID-S2-REQ]. A mode also permits an SNDU to be fragmented
with the remaining fragments sent in a later BBFrame(s), while
preserving the original order of each SNDU sent to a specific
MAC/NPA address over a Stream. Where there is sufficient space, the
method permits a BBFrame to carry more than one SNDU (or part there
of), sometimes known as Packing. All parts comprising an SNDU are
assigned to the same Stream.
In ULE and MPE [ETSI-DAT], each SNDU carries a 32-bit CRC field in
the last four bytes of the SNDU. The purpose of this CRC is to
protect the SNDU (header, and payload) from undetected reassembly
errors and errors introduced by unexpected software / hardware
operation. This also serves to verify the delineation (framing) of
PDUs and may detect the presence of uncorrected errors from the
physical link
When an SNDU is sent over a DVB-S2 subnetwork using GSE, the
Integrity protection is provided by a CRC at the baseband frame
level, using a CRC in the final bytes of the DataField.
Fairhurst Expires July 2007 [page 16]
INTERNET DRAFT Extension Formats for the ULE Encapsulation Mar 2007
[RFC EDITOR NOTE:
This section must be deleted prior to publication]
DOCUMENT HISTORY
Individual Draft 00
This draft complements a study item in the DVB-GBS in this area to
define a Generic Stream Encapsulation (GSE). Comments relating to
this document will be gratefully received by the author(s) and may
also be sent to ip-dvb mailing list at: ip-dvb@erg.abdn.ac.uk
Individual Draft 01
Co-Author Added.
This draft updates the language and format.
This draft fixes problems with the concatenation mode, and defines a
new header format that restricts the use of the Type field so that
all concatenated PDUs MUST have the same Type.
Future versions of this draft may define additional Extension
Headers, proposals and ideas are welcome via the IETF ipdvb mailing
list. Possible extensions include those for encapsulation FEC, Link
parameter negotiation (e.g. for header compression), and support for
ATM/ULE.
Working Group Draft 00
Fixed editorial mistakes from Christian Praehauser and ID style for
WG adoption.
Working Group Draft 01
Corrected contact info for Bernhard.
Added TimeStamp Options
Corrected NITS in draft
[END of RFC EDITOR NOTE]
Fairhurst Expires July 2007 [page 17]
