draft-ietf-ipdvb-ule-04.txt   draft-ietf-ipdvb-ule-05.txt 
Internet Engineering Task Force Gorry Fairhurst Internet Engineering Task Force Gorry Fairhurst
Internet Draft University of Aberdeen, U.K. Internet Draft University of Aberdeen
Document: draft-ietf-ipdvb-ule-04.txt Bernhard Collini-Nocker Document: draft-ietf-ipdvb-ule-05.txt Bernhard Collini-Nocker
University of Salzburg, A University of Salzburg
ipdvb WG ipdvb WG
Category: Draft, Intended Standards Track January 2005 Category: Draft, Intended Standards Track February 2005
Ultra Lightweight Encapsulation (ULE) for transmission of Ultra Lightweight Encapsulation (ULE) for transmission of
IP datagrams over MPEG-2/DVB networks IP datagrams over an MPEG-2 Transport Stream
Status of this Draft Status of this Draft
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of RFC 3668. aware will be disclosed, in accordance with Section 6 of RFC 3668.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at line 36 skipping to change at line 36
documents at any time. It is inappropriate to use Internet-Drafts as documents at any time. It is inappropriate to use Internet-Drafts as
reference material or to cite them other than as "work in progress". reference material or to cite them other than as "work in progress".
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/1id-abstracts.html http://www.ietf.org/1id-abstracts.html
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
Abstract Abstract
The MPEG-2 TS has been widely accepted not only for providing The MPEG-2 Transport Stream (TS) has been widely accepted not only
digital TV services, but also as a subnetwork technology for for providing digital TV services, but also as a subnetwork
building IP networks. This document describes an Ultra Lightweight technology for building IP networks.
Encapsulation (ULE) mechanism for the transport of IPv4 and IPv6
Datagrams and other network protocol packets directly over ISO MPEG- This document describes an Ultra Lightweight Encapsulation (ULE)
2 Transport Streams (TS) as TS Private Data. ULE supports an mechanism for the transport of IPv4 and IPv6 Datagrams and other
extension format that allows it to carry both optional (with an network protocol packets directly over the ISO MPEG-2 Transport
explicit extension length) and mandatory (with an implicit extension Stream as TS Private Data. ULE specifies a base encapsulation format
length) header information to assist in network/Receiver processing and supports an extension format that allows it to carry additional
of a SNDU. header information to assist in network/Receiver processing.
Expires July 2005 [page 1] Expires July 2005 [page 1]
Table of Contents Table of Contents
1. Introduction 1. Introduction
2. Conventions used in this document 2. Conventions used in this document
3. Description of method 3. Description of method
4. SNDU Format 4. SNDU Format
4.1 Destination Address Present (D) Field 4.1 Destination Address Absent (D) Field
4.2 Length Field 4.2 Length Field
4.3 End Indicator 4.3 End Indicator
4.4 Type Field 4.4 Type Field
4.4.1 Type 1: Next-Header Type Fields 4.4.1 Type 1: Next-Header Type Fields
4.4.2 Type 2: EtherType Compatible Type Fields 4.4.2 Type 2: EtherType Compatible Type Fields
4.5 SNDU Destination Address Field 4.5 SNDU Destination Address Field
4.6 SNDU Trailer CRC 4.6 SNDU Trailer CRC
4.7 Description of SNDU Formats 4.7 Description of SNDU Formats
4.7.1 End Indicator 4.7.1 End Indicator
4.7.2 IPv4 SNDU Encapsulation 4.7.2 IPv4 SNDU Encapsulation
skipping to change at line 96 skipping to change at line 96
12. Authors' Addresses 12. Authors' Addresses
13. IPR Notices 13. IPR Notices
13.1 Intellectual Property Statement 13.1 Intellectual Property Statement
13.2 Disclaimer of Validity 13.2 Disclaimer of Validity
14. Copyright Statement 14. Copyright Statement
14.1 Intellectual Property Statement 14.1 Intellectual Property Statement
14.2 Disclaimer of Validity 14.2 Disclaimer of Validity
15. IANA Considerations 15. IANA Considerations
15.1 IANA Guidelines 15.1 IANA Guidelines
ANNEXE A: Informative Appendix - SNDU Packing Examples ANNEX A: Informative Appendix - SNDU Packing Examples
ANNEXE B: Informative Appendix - SNDU Encapsulation ANNEX B: Informative Appendix - SNDU Encapsulation
Expires July 2005 [page 2] Expires July 2005 [page 2]
1. Introduction 1. Introduction
This document describes an encapsulation for transport of IP This document describes an encapsulation for transport of IP
datagrams, or other network layer packets, over ISO MPEG-2 Transport datagrams, or other network layer packets, over ISO MPEG-2 Transport
Streams [ISO-MPEG; ID-ipdvb-arch]. It is suited to services based Streams [[ISO-MPEG2; ID-ipdvb-arch]. It is suited to services based
on MPEG-2, for example the Digital Video Broadcast (DVB) on MPEG-2, for example the Digital Video Broadcast (DVB)
architecture, the Advanced Television Systems Committee (ATSC) architecture, the Advanced Television Systems Committee (ATSC)
system [ATSC; ATSC-G], and other similar MPEG-2 based transmission system [ATSC; ATSC-G], and other similar MPEG-2 based transmission
systems. Such systems provide unidirectional (simplex) physical and systems. Such systems provide unidirectional (simplex) physical and
link layer standards. Support has been defined for a wide range of link layer standards. Support has been defined for a wide range of
physical media (e.g. Terrestrial TV [ETSI-DVBT; ATSC-PSIP-TC], physical media (e.g. Terrestrial TV [ETSI-DVBT; ATSC-PSIP-TC],
Satellite TV [ETSI-DVBS; ATSC-S], Cable Transmission [ETSI-DVBC; Satellite TV [ETSI-DVBS; ATSC-S], Cable Transmission [ETSI-DVBC;
ATSC-PSIP-TC]). Bi-directional (duplex) links may also be ATSC-PSIP-TC]). Bi-directional (duplex) links may also be
established using these standards (e.g., DVB defines a range of established using these standards (e.g., DVB defines a range of
return channel technologies, including the use of two-way satellite return channel technologies, including the use of two-way satellite
links [ETSI-RCS] and dial-up modem links [RFC3077]). links [ETSI-RCS] and dial-up modem links [RFC3077]).
Protocol Data Units, PDUs, (Ethernet Frames, IP datagrams or other Protocol Data Units, PDUs, (Ethernet Frames, IP datagrams or other
network layer packets) for transmission over an MPEG-2 Transport network layer packets) for transmission over an MPEG-2 Transport
Multiplex are passed to an Encapsulator. This formats each PDU into Multiplex are passed to an Encapsulator. This formats each PDU into
a SubNetwork Data Unit (SNDU) [RFC3819] by adding an encapsulation a SubNetwork Data Unit (SNDU) by adding an encapsulation header and
header and an integrity check trailer. The SNDU is fragmented into a an integrity check trailer. The SNDU is fragmented into a series of
series of TS Packets) that are sent over a single TS Logical TS Packets that are sent over a single TS Logical Channel.
Channel.
The MPEG-2 specification [ISO-MPEG2] requires conformant TS
Multiplexes to provide Program Specific Information (PSI) for
each stream in the TS Multiplex. Other MPEG-2 based transmission
standards may also define Service Information (SI). This
information may allow Receivers and Re-multiplexors
[draft-ipdvb-arch] to locate a specific ULE Stream (i.e., the PID
value of the TS Logical Channel that carries a ULE Stream). The
conditions under which this information is required, and the
format in which it is to be provided is beyond the scope of
this document. Addressing and mapping issues for ULE over MPEG-2
are also described in [draft-ipdvb-ar].
Expires July 2005 [page 3] Expires July 2005 [page 3]
2. Conventions used in this document 2. Conventions used in this document
The capitalized 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
[RFC2119].
Other terms used in this document are defined below:
Adaptation Field: An optional variable-length extension field of the Adaptation Field: An optional variable-length extension field of the
fixed-length TS Packet header, intended to convey clock references fixed-length TS Packet header, intended to convey clock references
and timing and synchronization information as well as stuffing over and timing and synchronization information as well as stuffing over
an MPEG-2 Multiplex [ISO-MPEG]. an MPEG-2 Multiplex [ISO-MPEG2].
AFC: Adaptation Field Control [ISO_MPEG]. A pair of bits carried in AFC: Adaptation Field Control [ISO_MPEG]. A pair of bits carried in
the TS Packet header that signal the presence of the Adaptation the TS Packet header that signal the presence of the Adaptation
Field and/or TS Packet payload. Field and/or TS Packet payload.
ATSC: Advanced Television Systems Committee [ATSC]. A framework and ATSC: Advanced Television Systems Committee [ATSC]. A framework and
a set of associated standards for the transmission of video, audio, a set of associated standards for the transmission of video, audio,
and data using the ISO MPEG-2 standard. and data using the ISO MPEG-2 standard.
b: bit. For example, one byte consists of 8b.
B: Byte. Groups of bytes are represented in Internet byte order.
DSM-CC: Digital Storage Media Command and Control [ISO-DSMCC]. A DSM-CC: Digital Storage Media Command and Control [ISO-DSMCC]. A
format for transmission of data and control information defined by format for transmission of data and control information in an MPEG-2
the ISO MPEG-2 standard that is carried in an MPEG-2 Private Private Section, defined by the ISO MPEG-2 standard.
Section.
DVB: Digital Video Broadcast [ETSI-DVB]. A framework and set of DVB: Digital Video Broadcast [ETSI-DVB]. A framework and set of
associated standards published by the European Telecommunications associated standards published by the European Telecommunications
Standards Institute (ETSI) for the transmission of video, audio, and Standards Institute (ETSI) for the transmission of video, audio, and
data, using the ISO MPEG-2 Standard. data, using the ISO MPEG-2 Standard.
Encapsulator: A network device that receives PDUs and formats these Encapsulator: A network device that receives PDUs and formats these
into Payload Units (known here as SNDUs) for output as a stream of into Payload Units (known here as SNDUs) for output as a stream of
TS Packets. TS Packets.
End Indicator: A value that indicates to the Receiver that there are End Indicator: A value that indicates to the Receiver that there are
no further SNDUs present within the current TS Packet. no further SNDUs present within the current TS Packet.
MAC: Medium Access and Control. The link layer header of the LLC: Logical Link Control [ISO-8802-2]. A link layer protocol
Ethernet IEEE 802 standard of protocols, consisting of a 6B defined by the IEEE 802 standard, which follows the Ethernet MAC
destination address, 6B source address, and 2B type field (see also Header.
NPA).
MAC: Medium Access Control [IEEE-802.3]. A link layer protocol
defined by the IEEE 802.3 standard (or by Ethernet v2 [DIX]).
MAC Header: The link layer header of the IEEE 802.3 standard [IEEE-
802.3] or Ethernet v2 [DIX]. It consists of a 6B destination
address, 6B source address, and 2B type field (see also NPA, LLC).
Expires July 2005 [page 4]
MPE: Multiprotocol Encapsulation [ETSI-DAT; ATSC-DAT ; ATSC-DATG]. A MPE: Multiprotocol Encapsulation [ETSI-DAT; ATSC-DAT ; ATSC-DATG]. A
scheme that encapsulates PDUs, forming a DSM-CC Table Section. Each scheme that encapsulates PDUs, forming a DSM-CC Table Section. Each
Section is sent in a series of TS Packets using a single TS Logical Section is sent in a series of TS Packets using a single TS Logical
Channel. Channel.
MPEG-2: A set of standards specified by the Motion Picture Experts MPEG-2: A set of standards specified by the Motion Picture Experts
Group (MPEG), and standardized by the International Standards Group (MPEG), and standardized by the International Standards
Organisation (ISO) [ISO-MPEG]. Organisation (ISO/IEC 113818-1) [ISO-MPEG2], and ITU-T (in H.220).
Next-Header: A Type value indicating an Extension Header. Next-Header: A Type value indicating an Extension Header.
NPA: Network Point of Attachment. In this document, refers to a 6 B NPA: Network Point of Attachment. In this document, refers to a 6
destination address (resembling an IEEE MAC address) within the byte destination address (resembling an IEEE MAC address) within the
MPEG-2 transmission network that is used to identify individual MPEG-2 transmission network that is used to identify individual
Receivers or groups of Receivers. Receivers or groups of Receivers.
Expires July 2005 [page 4]
Packing Threshold: A period of time an Encapsulator is willing to Packing Threshold: A period of time an Encapsulator is willing to
defer transmission of a partially filled TS-Packet to accumulate defer transmission of a partially filled TS-Packet to accumulate
more SNDUs, rather than use Padding. After the Packet Threshold more SNDUs, rather than use Padding. After the Packet Threshold
period, the Encapsulator uses Padding to send the partially filled period, the Encapsulator uses Padding to send the partially filled
TS-Packet. TS-Packet.
PDU: Protocol Data Unit. Examples of a PDU include Ethernet frames, PDU: Protocol Data Unit. Examples of a PDU include Ethernet frames,
IPv4 or IPv6 datagrams, and other network packets. IPv4 or IPv6 datagrams, and other network packets.
PES: Packetized Elementary Steam [ISO-MPEG]. A format of MPEG-2 TS PES: Packetized Elementary Steam [ISO-MPEG2]. A format of MPEG-2 TS
packet payload usually used for video or audio information. packet payload usually used for video or audio information.
PID: Packet Identifier [ISO_MPEG]. A 13 bit field carried in the PID: Packet Identifier [ISO-MPEG2]. A 13 bit field carried in the
header of TS Packets. This is used to identify the TS Logical header of TS Packets. This is used to identify the TS Logical
Channel to which a TS Packet belongs [ISO-MPEG]. The TS Packets Channel to which a TS Packet belongs [ISO-MPEG2]. The TS Packets
forming the parts of a Table Section, PES, or other Payload Unit forming the parts of a Table Section, PES, or other Payload Unit
must all carry the same PID value. The all 1s PID value indicates a must all carry the same PID value. The all 1s PID value indicates a
Null TS Packet introduced to maintain a constant bit rate of a TS Null TS Packet introduced to maintain a constant bit rate of a TS
Multiplex. There is no required relationship between the PID values Multiplex. There is no required relationship between the PID values
used for TS Logical Channels transmitted using different TS used for TS Logical Channels transmitted using different TS
Multiplexes. Multiplexes.
PP: Payload Pointer [ISO-MPEG]. An optional one byte pointer that PP: Payload Pointer [ISO-MPEG2]. An optional one byte pointer that
directly follows the TS Packet header. It contains the number of directly follows the TS Packet header. It contains the number of
bytes between the end of the TS Packet header and the start of a bytes between the end of the TS Packet header and the start of a
Payload Unit. The presence of the Payload Pointer is indicated by Payload Unit. The presence of the Payload Pointer is indicated by
the value of the PUSI bit in the TS Packet header. The Payload the value of the PUSI bit in the TS Packet header. The Payload
Pointer is present in DSM-CC, and Table Sections, it is not present Pointer is present in DSM-CC, and Table Sections, it is not present
in TS Logical Channels that use the PES-format. in TS Logical Channels that use the PES-format.
Private Section: A syntactic structure constructed in accordance Private Section: A syntactic structure constructed in accordance
with Table 2-30 of [ISO-MPEG]. The structure may be used to identify with Table 2-30 of [ISO-MPEG2]. The structure may be used to
private information (i.e. not defined by [ISO-MPEG]) relating to one identify private information (i.e. not defined by [ISO-MPEG2])
or more elementary streams, or a specific MPEG-2 program, or the relating to one or more elementary streams, or a specific MPEG-2
entire Transport Stream. Other Standards bodies, e.g. ETSI, ATSC, program, or the entire Transport Stream. Other Standards bodies,
have defined sets of table structures using the private_section e.g. ETSI, ATSC, have defined sets of table structures using the
structure. A Private Section is transmitted as a sequence of TS private_section structure. A Private Section is transmitted as a
Packets using a TS Logical Channel. A TS Logical Channel may carry
sections from more than one set of tables.
PSI: Program Specific Information [ISO-MPEG]. PSI is used to convey Expires July 2005 [page 5]
sequence of TS Packets using a TS Logical Channel. A TS Logical
Channel may carry sections from more than one set of tables.
PSI: Program Specific Information [ISO-MPEG2]. PSI is used to convey
information about services carried in a TS Multiplex. It is carried information about services carried in a TS Multiplex. It is carried
in one of four specifically identified table section constructs in one of four specifically identified table section constructs
[ISO-MPEG], see also SI Table. [ISO-MPEG2], see also SI Table.
PSI: Program Specific Information [ISO-MPEG]. Tables used to convey PSI: Program Specific Information [ISO-MPEG2]. Tables used to convey
information about the service carried in a TS Multiplex. The set of information about the service carried in a TS Multiplex. The set of
PSI tables is defined by MPEG-2 [ISO-MPEG]. See also SI Table. PSI tables is defined by MPEG-2 [ISO-MPEG2]. See also SI Table.
PU: Payload Unit. A sequence of bytes sent using a TS. Examples of PU: Payload Unit. A sequence of bytes sent using a TS. Examples of
Payload Units include: an MPEG-2 Table Section or a ULE SNDU. Payload Units include: an MPEG-2 Table Section or a ULE SNDU.
Expires July 2005 [page 5] PUSI: Payload_Unit_Start_Indicator [ISO-MPEG2]. A single bit flag
PUSI: Payload_Unit_Start_Indicator [ISO-MPEG]. A single bit flag
carried in the TS Packet header. A PUSI value of zero indicates that carried in the TS Packet header. A PUSI value of zero indicates that
the TS Packet does not carry the start of a new Payload Unit. A PUSI the TS Packet does not carry the start of a new Payload Unit. A PUSI
value of one indicates that the TS Packet does carry the start of a value of one indicates that the TS Packet does carry the start of a
new Payload Unit. In ULE, a PUSI bit set to 1 also indicates the new Payload Unit. In ULE, a PUSI bit set to 1 also indicates the
presence of a one byte Payload Pointer (PP). presence of a one byte Payload Pointer (PP).
Receiver: An equipment that processes the signal from a TS Multiplex Receiver: Equipment that processes the signal from a TS Multiplex
and performs filtering and forwarding of encapsulated PDUs to the and performs filtering and forwarding of encapsulated PDUs to the
network-layer service (or bridging module when operating at the link network-layer service (or bridging module when operating at the link
layer). layer).
SI Table: Service Information Table [ISO-MPEG]. In this document, SI Table: Service Information Table [ISO-MPEG2]. In this document,
this term describes a table that is used to convey information about this term describes a table that is been defined by another
the services carried in a TS Multiplex, that has been defined by standards body to convey information about the services carried in a
another standards body. A Table may consist of one or more Table TS Multiplex. A Table may consist of one or more Table Sections,
Sections, however all sections of a particular SI Table must be however all sections of a particular SI Table must be carried over a
carried over a single TS Logical Channel [ISO-MPEG]. single TS Logical Channel [ISO-MPEG2].
SNDU: Subnetwork Data Unit [RFC3819]. An encapsulated PDU sent as an SNDU: Subnetwork Data Unit. An encapsulated PDU sent as an MPEG-2
MPEG-2 Payload Unit. Payload Unit.
Table Section: A Payload Unit carrying all or a part of an SI or PSI Table Section: A Payload Unit carrying all or a part of an SI or PSI
Table [ISO-MPEG]. Table [ISO-MPEG2].
TS: Transport Stream [ISO-MPEG], a method of transmission at the TS: Transport Stream [ISO-MPEG2], a method of transmission at the
MPEG-2 level using TS Packets; it represents level 2 of the ISO/OSI MPEG-2 level using TS Packets; it represents layer 2 of the ISO/OSI
reference model. See also TS Logical Channel and TS Multiplex. reference model. See also TS Logical Channel and TS Multiplex.
TS Header: The 4 byte header of a TS Packet [ISO-MPEG]. Expires July 2005 [page 6]
TS Header: The 4 byte header of a TS Packet [ISO-MPEG2]. Each 188B
TS Packet incorporates a 4B header with the following fields (those
referenced within this document are marked with *):
Field Length Name/Purpose
(in bits)
8b Synchronisation pattern equal 0x47
*1b Transport Error Indicator
*1b Payload Unit Start Indicator (PUSI)
1b Transport Priority
*13b Packet IDentifier (PID)
2b Transport scrambling control
*2b Adaptation Field Control (AFC)
*4b Continuity Counter (CC)
TS Logical Channel: Transport Stream Logical Channel. In this TS Logical Channel: Transport Stream Logical Channel. In this
document, this term identifies a channel at the MPEG-2 level [ISO- document, this term identifies a channel at the MPEG-2 level
MPEG]. It exists at level 2 of the ISO/OSI reference model. All [ISO-MPEG2]. This exists at level 2 of the ISO/OSI reference model.
packets sent over a TS Logical Channel carry the same PID value All packets sent over a TS Logical Channel carry the same PID
(this value is unique within a specific TS Multiplex). According to value (this value is unique within a specific TS Multiplex). The
MPEG-2, some TS Logical Channels are reserved for specific term "Stream" is defined in MPEG-2 [ISO-MPEG2]. This describes the
signalling purposes. Other standards (e.g., ATSC, DVB) also reserve content carried by a specific TS Logical Channel (see, ULE Stream).
specific TS Logical Channels. Some PID values are reserved (by MPEG-2) for specific signalling.
Other standards (e.g., ATSC, DVB) also reserve specific PID values.
TS Multiplex: In this document, this term defines a set of MPEG-2 TS TS Multiplex: In this document, this term defines a set of MPEG-2 TS
Logical Channels sent over a single lower layer connection. This may Logical Channels sent over a single lower layer connection. This may
be a common physical link (i.e. a transmission at a specified symbol be a common physical link (i.e. a transmission at a specified symbol
rate, FEC setting, and transmission frequency) or an encapsulation rate, FEC setting, and transmission frequency) or an encapsulation
provided by another protocol layer (e.g. Ethernet, or RTP over IP). provided by another protocol layer (e.g. Ethernet, or RTP over IP).
The same TS Logical Channel may be repeated over more than one TS The same TS Logical Channel may be repeated over more than one TS
Multiplex (possibly associated with a different PID value) [ID- Multiplex (possibly associated with a different PID value) [ID-
ipdvb-arch], for example to redistribute the same multicast content ipdvb-arch], for example to redistribute the same multicast content
to two terrestrial TV transmission cells. to two terrestrial TV transmission cells.
Expires July 2005 [page 6]
TS Packet: A fixed-length 188B unit of data sent over a TS Multiplex TS Packet: A fixed-length 188B unit of data sent over a TS Multiplex
[ISO-MPEG]. Each TS Packet carries a 4B header, plus optional [ISO-MPEG2]. Each TS Packet carries a 4B header, plus optional
overhead including an Adaptation Field, encryption details and time overhead including an Adaptation Field, encryption details and time
stamp information to synchronise a set of related TS Logical stamp information to synchronise a set of related TS Logical
Channels. The 188B TS Packet incorporates a 4B header with the Channels.
following fields (those referenced within this document are marked
with *):
Field Length Name/Purpose
(in bits)
8b Synchronisation pattern equal 0x47 ULE Stream: An MPEG-2 TS Logical Channel that carries only ULE
*1b Transport Error Indicator encapsulated PDUs. ULE Streams may be identified by definition of
*1b Payload Unit Start Indicator (PUSI) a stream_type in SI/PSI [ISO_MPEG2].
1b Transport Priority
*13b Packet IDentifier (PID)
2b Transport scrambling control
*2b Adaptation Field Control (AFC)
*4b Continuity Counter (CC)
Expires July 2005 [page 7] Expires July 2005 [page 7]
3. Description of the Method 3. Description of the Method
PDUs (IP packets, Ethernet frames or packets from other network PDUs (IP packets, Ethernet frames or packets from other network
protocols) are encapsulated to form a Subnetwork Data Unit (SNDU). protocols) are encapsulated to form a Subnetwork Data Unit (SNDU).
The SNDU is transmitted over an MPEG-2 transmission network by The SNDU is transmitted over an MPEG-2 transmission network by
placing it either in the payload of a single TS Packet, or if placing it either in the payload of a single TS Packet, or if
required, an SNDU may be fragmented into a series of TS Packets. required, an SNDU may be fragmented into a series of TS Packets.
Where there is sufficient space, the method permits a single TS Where there is sufficient space, the method permits a single TS
Packet to carry more than one SNDU (or part there of), sometimes Packet to carry more than one SNDU (or part there of), sometimes
known as Packing. All TS Packets comprising a SNDU MUST be assigned known as Packing. All TS Packets comprising an SNDU MUST be assigned
the same PID, and therefore form a part of the same TS Logical the same PID, and therefore form a part of the same TS Logical
Channel. Channel.
The ULE encapsulation is limited to TS private streams only. The The ULE encapsulation is limited to TS private streams only. The
header of each TS Packet carries a one bit Payload Unit Start header of each TS Packet carries a one bit Payload Unit Start
Indicator (PUSI) field. The PUSI identifies the start of a payload Indicator (PUSI) field. A PUSI field with a value of 1 indicates the
unit (SNDU) within the MPEG-2 TS Packet payload. The semantics of presence of at least one Payload Unit (SNDU) within the TS Packet
the PUSI bit are defined for PES and PSI packets [ISO-MPEG]; for payload. The semantics of the PUSI bit are defined for PES and PSI
private data, its use is not defined in the MPEG-2 Standard. In ULE, packets [ISO-MPEG2]; for private data, its use is not defined in the
although being private data, the operation follows that of PSI MPEG-2 Standard. In ULE, although being private data, the operation
packets. Hence, the following PUSI values are defined: follows that of PSI packets. Hence, the following PUSI values are
defined:
0: The TS Packet does NOT contain the start of a SNDU, but 0: The TS Packet does NOT contain the start of an SNDU, but
contains the continuation, or end of a SNDU; contains the continuation, or end of an SNDU;
1: The TS Packet contains the start of a SNDU, and a one byte 1: The TS Packet contains the start of an SNDU, and a one byte
Payload Pointer follows the last byte of the TS Packet header. Payload Pointer follows the last byte of the TS Packet header.
If a Payload Unit (SNDU) finishes before the end of a TS Packet If a Payload Unit (SNDU) finishes before the end of a TS Packet
payload, but it is not intended to start another Payload Unit, a payload, but it is not intended to start another Payload Unit, a
stuffing procedure fills the remainder of the TS Packet payload with stuffing procedure fills the remainder of the TS Packet payload with
bytes with a value 0xFF [ISO-MPEG2], known as Padding. bytes with a value 0xFF [ISO-MPEG2], known as Padding.
A Receiver processing MPEG-2 Table Sections that receives a value of A Receiver processing MPEG-2 Table Sections that receives a value of
0xFF in place of the table_id field, interprets this as 0xFF in place of the table_id field, interprets this as
Padding/Stuffing and silently discards the remainder of the TS Padding/Stuffing and silently discards the remainder of the TS
skipping to change at line 363 skipping to change at line 397
to include stuffing bytes before a TS Packet payload. Adaptation to include stuffing bytes before a TS Packet payload. Adaptation
Field stuffing is NOT used in this encapsulation method, and TS Field stuffing is NOT used in this encapsulation method, and TS
Packets from a ULE Encapsulator MUST be sent with an AFC value of Packets from a ULE Encapsulator MUST be sent with an AFC value of
'01'. For TS Logical Channels supporting ULE, Receivers MUST discard '01'. For TS Logical Channels supporting ULE, Receivers MUST discard
TS Packets that carry other AFC values. TS Packets that carry other AFC values.
Expires July 2005 [page 8] Expires July 2005 [page 8]
4. SNDU Format 4. SNDU Format
PDUs (IP packets and bridged Ethernet frames) are encapsulated using PDUs are encapsulated using ULE to form an SNDU. (Each SNDU is an
ULE to form a SNDU. (Each SNDU is an MPEG-2 Payload Unit.) The MPEG-2 Payload Unit.) The encapsulation format to be used for PDUs
encapsulation format to be used for PDUs is illustrated below: is illustrated below:
< ----------------------------- SNDU ----------------------------- > < ----------------------------- SNDU ----------------------------- >
+-+-------------------------------------------------------+--------+ +-+-------------------------------------------------------+--------+
|D| Length | Type | PDU | CRC-32 | |D| Length | Type | PDU | CRC-32 |
+-+-------------------------------------------------------+--------+ +-+-------------------------------------------------------+--------+
Figure 1: SNDU Encapsulation Figure 1: SNDU Encapsulation
All multi-byte values in ULE (including Length, Type, and All multi-byte values in ULE (including Length, Type, and
Destination fields) are transmitted in network byte order (most Destination fields) are transmitted in network byte order (most
significant byte first). The most significant bit of each byte is significant byte first). The most significant bit of each byte is
placed in the left-most position of the 8-bit field. Appendix A placed in the left-most position of the 8-bit field. Appendix A
provides informative examples of usage. provides informative examples of usage.
4.1 Destination Address Present (D) Field 4.1 Destination Address Absent (D) Field
The most significant bit of the Length Field carries the value of The most significant bit of the Length Field carries the value of
the Destination Address Present Field, the D-bit. A value of 0 the Destination Address Absent Field, the D-bit. A value of 0
indicates the presence of the Destination Address Field (see section indicates the presence of the Destination Address Field (see section
4.5). A value of 1 indicates that a Destination Address Field is not 4.5). A value of 1 indicates that a Destination Address Field is not
present (i.e. it is omitted). present.
By default, the D-bit value SHOULD be set to a value of 0 (see 4.5), By default, the D-bit value SHOULD be set to a value of 0 (see 4.5),
except for the transmission of an End Indicator (see 4.3), for which except for the transmission of an End Indicator (see 4.3), for which
this bit MUST be set to the value of 1. this bit MUST be set to the value of 1.
4.2 Length Field 4.2 Length Field
A 15-bit value that indicates the length, in bytes, of the SNDU A 15-bit value that indicates the length, in bytes, of the SNDU
(encapsulated Ethernet frame, IP datagram or other packet) counted counted from the byte following the Type field, up to and including
from the byte following the Type field, up to and including the CRC. the CRC. Note the special case described in 4.3.
Note the special case described in 4.3.
4.3 End Indicator 4.3 End Indicator
When the first two bytes of a SNDU have the value 0xFFFF, this When the first two bytes of an SNDU have the value 0xFFFF, this
denotes an End Indicator (i.e., all 1s length combined with a D-bit denotes an End Indicator (i.e., all 1s length combined with a D-bit
value of 1). This indicates to the Receiver that there are no value of 1). This indicates to the Receiver that there are no
further SNDUs present within the current TS Packet (see section 6), further SNDUs present within the current TS Packet (see section 6),
and that no Destination Address Field is present. The value 0xFF has and that no Destination Address Field is present. The value 0xFF has
specific semantics in MPEG-2 framing, where it is used to indicate specific semantics in MPEG-2 framing, where it is used to indicate
the presence of Padding. This use resembles [ISO-DSMCC]. the presence of Padding. This use resembles [ISO-DSMCC].
Expires July 2005 [page 9] Expires July 2005 [page 9]
4.4 Type Field 4.4 Type Field
The 16-bit Type field indicates the type of payload carried in a The 16-bit Type field indicates the type of payload carried in an
SNDU, or the presence of a Next-Header. The set of values that may SNDU, or the presence of a Next-Header. The set of values that may
be assigned to this field is divided into two parts, similar to the be assigned to this field is divided into two parts, similar to the
allocations for Ethernet. allocations for Ethernet.
EtherTypes were originally specified by Xerox under the DIX EtherTypes were originally specified by Xerox under the Ethernet v2
framework for Ethernet. After specification of IEEE 802.3 [LLC], the Specification [DIX]. After specification of IEEE 802.3 [IEEE 802.3;
set of EtherTypes less than 1536 (0x0600), assumed the role of a ISO-8802-2], the set of EtherTypes less than 1536 (0x0600), assumed
length indicator. Ethernet receivers use this feature to the role of a length indicator. Ethernet receivers use this feature
discriminate LLC format frames. Hence any IEEE EtherType < 1536 to discriminate LLC format frames. Hence any IEEE EtherType < 1536
indicates an LLC frame, and the actual value indicates the length of indicates an LLC frame, and the actual value indicates the length of
the LLC frame. the LLC frame.
There is a potential ambiguous case when a Receiver receives a PDU There is a potential ambiguous case when a Receiver receives a PDU
with two length fields: The Receiver would need to validate the with two length fields: The Receiver would need to validate the
actual length and the Length field and ensure that inconsistent actual length and the Length field and ensure that inconsistent
values are not propagated by the network. Specification of two values are not propagated by the network. Specification of two
independent length fields is therefore undesirable. In the ULE independent length fields is therefore undesirable. In the ULE
header, this is avoided in the SNDU header by including only one header, this is avoided in the SNDU header by including only one
length value, but bridging of LLC frames re-introduces this length value, but bridging of LLC frames re-introduces this
skipping to change at line 455 skipping to change at line 488
type assignments for Ethernet and recorded in the IANA EtherType type assignments for Ethernet and recorded in the IANA EtherType
registry. registry.
4.4.1 Type 1: Next-Header Type Fields 4.4.1 Type 1: Next-Header Type Fields
The first part of the Type space corresponds to the values 0 to 1535 The first part of the Type space corresponds to the values 0 to 1535
Decimal. These values may be used to identify link-specific Decimal. These values may be used to identify link-specific
protocols and/or to indicate the presence of Extension Headers that protocols and/or to indicate the presence of Extension Headers that
carry additional optional protocol fields (e.g. a bridging carry additional optional protocol fields (e.g. a bridging
encapsulation). Use of these values is co-ordinated by an IANA encapsulation). Use of these values is co-ordinated by an IANA
registry. registry. The following types are defined in this document:
Expires July 2005 [page 10]
The following types are defined in this document:
[XXX IANA ACTION REQUIRED XXX]
0x0000: Test SNDU, discarded by the Receiver.
0x0001: Bridged Ethernet Frame (i.e. MAC source address follows)
0x0100: Padding, ignored by the Receiver.
[XXX END OF IANA ACTION REQUIRED XXX] 0x0000: Test SNDU (see 5.1)
0x0001: Bridged Frame (see 5.2)
0x0100: Extension-Padding (see 5.3)
Expires July 2005 [page 10]
The remaining values within the first part of the Type space are The remaining values within the first part of the Type space are
reserved for Next-Header values allocated by the IANA. reserved for Next-Header values allocated by the IANA.
4.4.2 Type 2: EtherType Compatible Type Fields 4.4.2 Type 2: EtherType Compatible Type Fields
The second part of the Type space corresponds to the values between The second part of the Type space corresponds to the values between
0x600 (1536 decimal) and 0xFFFF. This set of type assignments 0x600 (1536 decimal) and 0xFFFF. This set of type assignments
follow DIX/IEEE assignments (but exclude use of this field as a follow DIX/IEEE assignments (but exclude use of this field as a
frame length indicator) [LLC]. All assignments in this space MUST frame length indicator). All assignments in this space MUST use the
use the values defined for IANA EtherType, the following two Type values defined for IANA EtherType, the following two Type values are
values are used as examples (taken from the IANA EtherTypes used as examples (taken from the IANA EtherTypes registry):
registry):
0x0800 : IPv4 Payload 0x0800: IPv4 Payload (see 4.7.2)
0x86DD : IPv6 Payload 0x86DD: IPv6 Payload (see 4.7.3)
4.5 SNDU Destination Address Field 4.5 SNDU Destination Address Field
The SNDU Destination Address Field is optional (see 4.1). This field The SNDU Destination Address Field is optional (see 4.1). This field
MUST be carried (i.e. D=0) for IP unicast packets destined to 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 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 connects multiple Receivers). A sender MAY omit this field (D=1) for
an IP unicast packet and/or multicast packets delivered to Receivers an IP unicast packet and/or multicast packets delivered to Receivers
that are able to utilise a discriminator field (e.g. the IPv4/IPv6 that are able to utilise a discriminator field (e.g. the IPv4/IPv6
destination address), which in combination with the PID value, could destination address, or a bridged MAC destination address), which in
be interpreted as a Link-Level address. combination with the PID value, could be interpreted as a Link-Level
address.
When the SNDU header indicates the presence of a SNDU Destination When the SNDU header indicates the presence of an SNDU Destination
Address field (i.e. D=0), a Network Point of Attachment, NPA, field Address field (i.e. D=0), a Network Point of Attachment, NPA, field
directly follows the fourth byte of the SNDU header. NPA directly follows the fourth byte of the SNDU header. NPA destination
destination addresses are 6 Byte numbers, normally expressed in addresses are 6 Byte numbers, normally expressed in hexadecimal,
hexadecimal, used to identify the Receiver(s) in a MPEG-2 used to identify the Receiver(s) in a MPEG-2 transmission network
transmission network that should process a received SNDU. The value that should process a received SNDU. The value 0x00:00:00:00:00:00,
0x00:00:00:00:00:00, MUST NOT be used as a destination address in a MUST NOT be used as a destination address in an SNDU. The least
SNDU. The least significant bit of the first byte of the address is significant bit of the first byte of the address is set to 1 for
set to 1 for multicast frames, and the remaining bytes specify the multicast frames, and the remaining bytes specify the link layer
link layer multicast address. The specific value 0xFF:FF:FF:FF:FF:FF multicast address. The specific value 0xFF:FF:FF:FF:FF:FF is the
is the link broadcast address, indicating this SNDU is to be link broadcast address, indicating this SNDU is to be delivered to
delivered to all Receivers. all Receivers.
IPv4 packets carrying an IPv4 subnetwork broadcast address need to
be delivered to all systems with the same network prefix. When a
SNDU Destination Address is present (D=0) the value MUST be set to
the NPA link broadcast address (0xFF:FF:FF:FF:FF:FF).
When the PDU is an IP multicast packet and an SNDU Destination
Address is present (D=0), the IP group destination address of the
multicast packet MUST be mapped to the multicast SNDU Destination
Address (following the method used to generate a destination MAC
address in Ethernet). The method for mapping IPv4 multicast
Expires July 2005 [page 11] Expires July 2005 [page 11]
addresses is specified in [RFC1112]. The method for mapping IPv6
multicast addresses is specified in [RFC2464].
4.6 SNDU Trailer CRC 4.6 SNDU Trailer CRC
Each SNDU MUST carry a 32-bit CRC field in the last four bytes of Each SNDU MUST carry a 32-bit CRC field in the last four bytes of
the SNDU. This position eases CRC computation by hardware. The CRC- the SNDU. This position eases CRC computation by hardware. The CRC-
32 polynomial is to be used. Examples where this polynomial is also 32 polynomial is to be used. Examples where this polynomial is also
employed include Ethernet, DSM-CC section syntax [ISO-DSMCC] and employed include Ethernet, DSM-CC section syntax [ISO-DSMCC] and
AAL5 [ITU3563]. This is a 32 bit value calculated according to the AAL5 [ITU3563]. This is a 32 bit value calculated according to the
generator polynomial represented 0x104C11DB7 in hexadecimal: generator polynomial represented 0x104C11DB7 in hexadecimal:
skipping to change at line 550 skipping to change at line 590
that includes the computed CRC-32 value. that includes the computed CRC-32 value.
The primary purpose of this CRC is to protect the SNDU (header, and The primary purpose of this CRC is to protect the SNDU (header, and
payload) from undetected reassembly errors and errors introduced by payload) from undetected reassembly errors and errors introduced by
unexpected software / hardware operation while the SNDU is in unexpected software / hardware operation while the SNDU is in
transit across the MPEG-2 subnetwork and during processing at the transit across the MPEG-2 subnetwork and during processing at the
encapsulation gateway and/or the Receiver. It may also detect the encapsulation gateway and/or the Receiver. It may also detect the
presence of uncorrected errors from the physical link (however, presence of uncorrected errors from the physical link (however,
these may also be detected by other means, e.g. section 7.3). these may also be detected by other means, e.g. section 7.3).
Expires July 2005 [page 12]
4.7 Description of SNDU Formats 4.7 Description of SNDU Formats
The format of a SNDU is determined by the combination of the The format of an SNDU is determined by the combination of the
Destination Address Present bit (D) and the SNDU Type Field. The Destination Address Absent bit (D) and the SNDU Type Field. The
simplest encapsulation places a PDU directly into a SNDU payload. simplest encapsulation places a PDU directly into an SNDU payload.
Some Type 1 encapsulations may require additional header fields. Some Type 1 encapsulations may require additional header fields.
These are inserted in the SNDU following the NPA destination address These are inserted in the SNDU following the NPA destination address
and directly preceding the PDU. and directly preceding the PDU.
The following SNDU Formats are defined here: The following SNDU Formats are defined here:
End Indicator: The Receiver should enter the Idle State (4.7.1). End Indicator: The Receiver should enter the Idle State (4.7.1).
IPv4 SNDU: The payload is a complete IPv4 datagram (4.7.2) IPv4 SNDU: The payload is a complete IPv4 datagram (4.7.2)
Expires July 2005 [page 12]
IPv6 SNDU: The payload is a complete IPv6 datagram (4.7.3). IPv6 SNDU: The payload is a complete IPv6 datagram (4.7.3).
Test SNDU: The payload will be discarded by the Receiver (5.1). Test SNDU: The payload will be discarded by the Receiver (5.1).
Bridged SNDU: The payload carries a bridged MAC or LLC frame (5.2). Bridged SNDU: The payload carries a bridged MAC frame (5.2).
Other formats may be defined through relevant assignments in the Other formats may be defined through relevant assignments in the
IEEE and IANA registries. IEEE and IANA registries.
4.7.1 End Indicator 4.7.1 End Indicator
The format of the End Indicator is shown in figure 2. This format The format of the End Indicator is shown in figure 2. This format
MUST carry a D-bit value of 1. MUST carry a D-bit value of 1.
0 1 2 3 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 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| 0x7FFF | |1| 0x7FFF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= Arbitrary number (>= 0) bytes with value 0xFF = = A sequence of zero or more bytes with a value 0xFF filling =
| | | the remainder of the TS Packet Payload |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SNDU Format for an End Indicator. Figure 2: Format for a ULE End Indicator.
Expires July 2005 [page 13]
4.7.2 IPv4 SNDU 4.7.2 IPv4 SNDU
IPv4 datagrams are directly transported using one of the two IPv4 datagrams are directly transported using one of the two
standard SNDU structures, in which the PDU is placed directly in the standard SNDU structures, in which the PDU is placed directly in the
SNDU payload. The two encapsulations are shown in figures 3 and 4. SNDU payload. The two encapsulations are shown in figures 3 and 4.
(Note that in this, and the following figures, the IP datagram (Note that in this, and the following figures, the IP datagram
payload is of variable size, and is directly followed by the CRC- payload is of variable size, and is directly followed by the CRC-
32). 32).
0 1 2 3 0 1 2 3
skipping to change at line 616 skipping to change at line 656
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
= IPv4 datagram = = IPv4 datagram =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) | | (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 3: SNDU Format for an IPv4 Datagram using L2 filtering (D=0). Figure 3: SNDU Format for an IPv4 Datagram using L2 filtering (D=0).
Expires July 2005 [page 13]
0 1 2 3 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 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 = 0x0800 | |1| Length (15b) | Type = 0x0800 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= IPv4 datagram = = IPv4 datagram =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) | | (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 4: SNDU Format for an IPv4 Datagram using L3 filtering (D=1). Figure 4: SNDU Format for an IPv4 Datagram using L3 filtering (D=1).
4.7.3 IPv6 SNDU Encapsulation 4.7.3 IPv6 SNDU Encapsulation
IPv6 datagrams are directly transported using one of the two IPv6 datagrams are directly transported using one of the two
standard SNDU structures, in which the PDU is placed directly in the standard SNDU structures, in which the PDU is placed directly in the
SNDU payload. The two encapsulations are shown in figures 5 and 6. SNDU payload. The two encapsulations are shown in figures 5 and 6.
Expires July 2005 [page 14]
0 1 2 3 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 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 = 0x086DD | |0| Length (15b) | Type = 0x86DD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiver Destination NPA Address (6B) | | Receiver Destination NPA Address (6B) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
= IPv6 datagram = = IPv6 datagram =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) | | (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 5: SNDU Format for an IPv6 Datagram using L2 filtering (D=0). Figure 5: SNDU Format for an IPv6 Datagram using L2 filtering (D=0).
0 1 2 3 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 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 = 0x086DD | |1| Length (15b) | Type = 0x86DD |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= IPv6 datagram = = IPv6 datagram =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) | | (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: SNDU Format for an IPv6 Datagram using L3 filtering (D=1) Figure 6: SNDU Format for an IPv6 Datagram using L3 filtering (D=1)
Expires July 2005 [page 14] Expires July 2005 [page 15]
5. Extension Headers 5. Extension Headers
This section describes an extension format for the ULE This section describes an extension format for the ULE
encapsulation. In ULE, a Type field value less than 1536 Decimal encapsulation. In ULE, a Type field value less than 1536 Decimal
indicates an Extension Header. These values are assigned from a indicates an Extension Header. These values are assigned from a
separate IANA registry defined for ULE. separate IANA registry defined for ULE.
The use of a single Type/Next-Header field simplifies processing and The use of a single Type/Next-Header field simplifies processing and
eliminates the need to maintain multiple IANA registries. The cost eliminates the need to maintain multiple IANA registries. The cost
is that each Extension Header requires at least 2 bytes. This is is that each Extension Header requires at least 2 bytes. This is
skipping to change at line 707 skipping to change at line 747
0 Indicates a Mandatory Extension Header 0 Indicates a Mandatory Extension Header
1 Indicates an Optional Extension Header of length 2B 1 Indicates an Optional Extension Header of length 2B
2 Indicates an Optional Extension Header of length 4B 2 Indicates an Optional Extension Header of length 4B
3 Indicates an Optional Extension Header of length 6B 3 Indicates an Optional Extension Header of length 6B
4 Indicates an Optional Extension Header of length 8B 4 Indicates an Optional Extension Header of length 8B
5 Indicates an Optional Extension Header of length 10B 5 Indicates an Optional Extension Header of length 10B
>=6 the combined H-LEN and H-TYPE values indicate the EtherType >=6 the combined H-LEN and H-TYPE values indicate the EtherType
of a PDU that directly follows this Type field. of a PDU that directly follows this Type field.
The H-LEN value indicates the total number of bytes in an Optional
Extension Header (including the 2B Type field).
A H-LEN of zero indicates a Mandatory Extension Header. Each A H-LEN of zero indicates a Mandatory Extension Header. Each
Mandatory Extension Header has a pre-defined length that is not Mandatory Extension Header has a pre-defined length that is not
communicated in the H-LEN field. No additional limit is placed on communicated in the H-LEN field. No additional limit is placed on
the maximum length of a Mandatory Extension Header. A Mandatory the maximum length of a Mandatory Extension Header. A Mandatory
Extension Header MAY modify the format or encoding of the enclosed Extension Header MAY modify the format or encoding of the enclosed
PDU (e.g. to perform encryption and/or compression). PDU (e.g. to perform encryption and/or compression).
The H-Type is a one byte field that is either one of 256 Mandatory The H-Type is a one byte field that is either one of 256 Mandatory
Header Extensions or one of 256 Optional Header Extensions. The set Header Extensions or one of 256 Optional Header Extensions. The set
of currently permitted values for both types of Extension Headers of currently permitted values for both types of Extension Headers
are defined by an IANA Registry (section 15). Registry values for are defined by an IANA Registry (section 15). Registry values for
Optional Extensions are specified in the form H=1 (i.e. a decimal Optional Extensions are specified in the form H=1 (i.e. a decimal
Expires July 2005 [page 16]
number in the range 256-511), but may be used with an H-Length value number in the range 256-511), but may be used with an H-Length value
in the range 1-5 (see example in 5.3). in the range 1-5 (see example in 5.3).
Expires July 2005 [page 15]
Two examples of Extension Headers are the Test_SNDU and the use of Two examples of Extension Headers are the Test_SNDU and the use of
Extension-Padding. The Test-SNDU Mandatory Extension Header results Extension-Padding. The Test-SNDU Mandatory Extension Header results
in the entire PDU being discarded. The Extension-Padding Optional in the entire PDU being discarded. The Extension-Padding Optional
Extension Header results in the following (if any) option header Extension Header results in the following (if any) option header
being ignored (i.e. a total of H-LEN 16-bit words). being ignored (i.e. a total of H-LEN 16-bit words).
The general format for an SNDU with Extension Headers is: The general format for an SNDU with Extension Headers is:
< -------------------------- SNDU ------------------------- > < -------------------------- SNDU ------------------------- >
+---+--------------------------------------------------+--------+ +---+--------------------------------------------------+--------+
skipping to change at line 766 skipping to change at line 810
Using this method, several Extension Headers MAY be chained in Using this method, several Extension Headers MAY be chained in
series. Figure 12 shows an SNDU including two Extension Headers. The series. Figure 12 shows an SNDU including two Extension Headers. The
values of T1 and T2 are both less than 1536 Decimal, each indicates values of T1 and T2 are both less than 1536 Decimal, each indicates
the presence of an Extension Header, rather than a directly the presence of an Extension Header, rather than a directly
following PDU. T3 has a value > 1535 indicating the EtherType of the following PDU. T3 has a value > 1535 indicating the EtherType of the
PDU being carried. Although an SNDU may contain an arbitrary number PDU being carried. Although an SNDU may contain an arbitrary number
of consecutive Extension Headers, it is not expected that SNDUs will of consecutive Extension Headers, it is not expected that SNDUs will
generally carry a large number of extensions. generally carry a large number of extensions.
Expires July 2005 [page 16] Expires July 2005 [page 17]
5.1 Test SNDU 5.1 Test SNDU
A Test SNDU (figure 10) is of Type 1. The structure of the Data A Test SNDU (figure 10) is of a Mandatory Extension Header of Type
1. This header must be the final (or only) extension header
specified in the header chain of a SNDU. The structure of the Data
portion of this SNDU is not defined by this document. All Receivers portion of this SNDU is not defined by this document. All Receivers
MAY record reception in a log file, but MUST then discard any Test MAY record reception in a log file, but MUST then discard any Test
SNDUs. The D-bit MAY be set in a TEST SNDU. SNDUs. The D-bit MAY be set in a TEST SNDU.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|D| Length (15b) | Type = 0x0000 | |D| Length (15b) | Type = 0x0000 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= Data (not forwarded by a Receiver) = = Data (not forwarded by a Receiver) =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) | | (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 10: SNDU Format for a Test SNDU Figure 10: SNDU Format for a Test SNDU
5.2 Bridge Frame SNDU Encapsulation 5.2 Bridge Frame SNDU Encapsulation
A bridged SNDU is of Type 1. The payload includes MAC address and A bridged SNDU is a Mandatory Extension Header of Type 1. It must be
Ether-Type fields together with the contents of a bridged MAC frame. the final (or only) extension header specified in the header chain
The SNDU has the format shown in figures 11 and 12. of a SNDU. The payload includes MAC address and EtherType [DIX] or
LLC Length [ISO-8802-2] fields together with the contents of a
bridged MAC frame. The SNDU has the format shown in figures 11 and
12.
When an NPA address is specified (D=0), Receivers MUST discard all
SNDUs that carry an NPA destination address that does NOT match
their own NPA address (or a broadcast/multicast address), the
payload of the remaining SNDUs are processed by the bridging rules
that follow. An SNDU without an NPA address (D=1) results in a
Receiver performing bridging processing on the payload of all
received SNDUs.
A Gateway MAY also use this encapsulation format to directly
communicate network protocol packets that require the LLC
encapsulation [ISO-8802-2]. To do this, it constructs an SNDU with a
Bridge Extension Header containing the intended destination MAC
address, the MAC source address of the Gateway, and the LLC-Length.
The PDU comprises an LLC header followed by the required payload.
The Gateway MAY choose to suppress the NPA address (see 4.5).
Expires July 2005 [page 18]
0 1 2 3 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 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 = 0x0001 | |0| Length (15b) | Type = 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Receiver Destination NPA Address (6B) | | Receiver Destination NPA Address (6B) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| MAC Destination Address (6B) | | MAC Destination Address (6B) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Source Address (6B) | | MAC Source Address (6B) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | EtherType (2B) | | | EtherType/LLC-Length (2B) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= (Contents of bridged MAC frame) = = (Contents of bridged MAC frame) =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) | | (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 11: SNDU Format for a Bridged Payload (D=0) Figure 11: SNDU Format for a Bridged Payload (D=0)
Expires July 2005 [page 17]
0 1 2 3 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 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 = 0x0001 | |1| Length (15b) | Type = 0x0001 |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| MAC Destination Address (6B) | | MAC Destination Address (6B) |
+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| MAC Source Address (6B) | | MAC Source Address (6B) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| EtherType (2B) | | | EtherType/LLC-Length (2B) | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ + +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +
| | | |
= (Contents of bridged MAC frame) = = (Contents of bridged MAC frame) =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) | | (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 12: SNDU Format for a Bridged Payload (D=1) Figure 12: SNDU Format for a Bridged Payload (D=1)
Note: The final two bytes of the bridging header also carry a Type The EtherType/LLC-Length field of a frame is defined according to
field (see section 5). In this special case, the extension mandatory IEEE 802.3 [IEEE-802.3; ISO-8802-2] (see section 5).
header format permits this to carry a LLC Length field, specified by
IEEE 802 [LLC] rather than an IANA assigned value.
When an NPA address is specified (D=0), Receivers MUST discard all In this special case, the extension mandatory header format permits
SNDUs that carry an NPA destination address that does NOT match this field may be interpreted as either an EtherType [DIX] or an LLC
their own NPA address (or a broadcast/multicast address), the
payload of the remaining SNDUs are processed by the bridging rules Expires July 2005 [page 19]
that follow. An SNDU without an NPA address (D=1) results in a Length field, specified by IEEE 802 [IEEE-802.3] rather a value
Receiver performing bridging processing on the payload of all assigned in the ULE Next Header Registry maintained by the IANA.
received SNDUs.
The MAC addresses in the frame being bridged SHOULD be assigned The MAC addresses in the frame being bridged SHOULD be assigned
according to the rules specified by the IEEE and may denote unknown, according to the rules specified by the IEEE and may denote unknown,
unicast, broadcast, and multicast link addresses. These MAC unicast, broadcast, and multicast link addresses. These MAC
addresses denote the intended recipient in the destination LAN, and addresses denote the intended recipient in the destination LAN, and
therefore have a different function to the NPA addresses carried in therefore have a different function to the NPA addresses carried in
the SNDU header. The EtherType field of a frame is defined according the SNDU header.
to Ethernet/LLC [LLC].
A frame Type < 1536 for a bridged frame, introduces a LLC Length A frame Type < 1536 for a bridged frame, introduces a LLC Length
field. The Receiver MUST check this length and discard any frame field. The Receiver MUST check this length and discard any frame
with a length greater than permitted by the SNDU payload size. with a length greater than permitted by the SNDU payload size.
In normal operation, it is expected that any padding appended to the In normal operation, it is expected that any padding appended to the
Ethernet frame SHOULD be removed prior to forwarding. This requires Ethernet frame SHOULD be removed prior to forwarding. This requires
the sender to be aware of such Ethernet padding (e.g. LLC). the sender to be aware of such Ethernet padding (e.g. [DIX; IEEE-
802.3]).
Expires July 2005 [page 18]
Ethernet frames received at the Encapsulator for onward transmission Ethernet frames received at the Encapsulator for onward transmission
over ULE carry a Local Area Network Frame Check sequence, LAN FCS, over ULE carry a Local Area Network Frame Check sequence, LAN FCS,
field (e.g. CRC-32 for Ethernet). The Encapsulator MUST check the field (e.g. CRC-32 for Ethernet [DIX; IEEE-802.3]). The Encapsulator
LAN-FCS value of all frames received, prior to further processing. MUST check the LAN-FCS value of all frames received, prior to
Frames received with an invalid LAN FCS MUST be discarded. After further processing. Frames received with an invalid LAN FCS MUST be
checking, the LAN FCS is then removed (i.e., it is NOT forwarded in discarded. After checking, the LAN FCS is then removed (i.e., it is
the bridged SNDU). As in other ULE frames, the Encapsulator appends NOT forwarded in the bridged SNDU). As in other ULE frames, the
a CRC-32 to the transmitted SNDU. At the Receiver, an appropriate Encapsulator appends a CRC-32 to the transmitted SNDU. At the
LAN-FCS field will be appended to the bridged frame prior to onward Receiver, an appropriate LAN-FCS field will be appended to the
transmission on the Ethernet interface. bridged frame prior to onward transmission on the Ethernet
interface.
This design is readily implemented using existing network interface This design is readily implemented using existing network interface
cards, and does not introduce an efficiency cost by transmitting two cards, and does not introduce an efficiency cost by transmitting two
integrity check fields for bridged frames. However, it also integrity check fields for bridged frames. However, it also
introduces the possibility that a frame corrupted within the introduces the possibility that a frame corrupted within the
processing performed at an Encapsulator and/or Receiver may not be processing performed at an Encapsulator and/or Receiver may not be
detected by the final recipient(s) (i.e. such corruption would not detected by the final recipient(s) (i.e. such corruption would not
normally result in an invalid LAN FCS). normally result in an invalid LAN FCS).
5.3 Extension-Padding Optional Extension Header 5.3 Extension-Padding Optional Extension Header
The Extension-Padding Optional Extension Header is specified by an The Extension-Padding Optional Extension Header is specified by an
IANA assigned H-Type value of 0x100. As in other Optional IANA assigned H-Type value of 0x100. As in other Optional
Extensions, the total length of the extension is indicated by the H- Extensions, the total length of the extension is indicated by the H-
LEN field (specified in 16-bit words). The extension field is formed LEN field (specified in 16-bit words). The extension field is formed
of a group of 1-5 16-bit fields. of a group of 1 to 5 16-bit fields.
For this specific option, only the last 16-bit word has an assigned For this specific option, only the last 16-bit word has an assigned
value, the sender SHOULD set the remaining values to 0x0000. The value, the sender SHOULD set the remaining values to 0x0000. The
last 16-bit field forms the Next-Header Type field. A Receiver MUST last 16-bit field forms the Next-Header Type field. A Receiver MUST
interpret the Type field, but MUST ignore any other fields of this interpret the Type field, but MUST ignore any other fields of this
Extension Header. Extension Header.
Expires July 2005 [page 19] Expires July 2005 [page 20]
6. Processing at the Encapsulator 6. Processing at the Encapsulator
The Encapsulator forms the PDUs queued for transmission into SNDUs The Encapsulator forms the PDUs queued for transmission into SNDUs
by adding a header and trailer to each PDU (section 4). It then by adding a header and trailer to each PDU (section 4). It then
segments the SNDU into a series of TS Packet payloads (figure 9). segments the SNDU into a series of TS Packet payloads (figure 9).
These are transmitted using a single TS Logical Channel over a TS These are transmitted using a single TS Logical Channel over a TS
Multiplex. The TS Multiplex may be processed by a number of MPEG-2 Multiplex. The TS Multiplex may be processed by a number of MPEG-2
(re)multiplexors before it is finally delivered to a Receiver [ID- (re)multiplexors before it is finally delivered to a Receiver [ID-
ipdvb-arch]. ipdvb-arch].
skipping to change at line 928 skipping to change at line 990
|Header| |CRC-32| |Header| |CRC-32|
+------+--------------------------------+------+ +------+--------------------------------+------+
/ / \ \ / / \ \
/ / \ \ / / \ \
/ / \ \ / / \ \
+--------+---------+ +--------+---------+ +--------+---------+ +--------+---------+ +--------+---------+ +--------+---------+
|MPEG-2TS| MPEG-2 |...|MPEG-2TS| MPEG-2 |...|MPEG-2TS| MPEG-2 | |MPEG-2TS| MPEG-2 |...|MPEG-2TS| MPEG-2 |...|MPEG-2TS| MPEG-2 |
| Header | Payload | | Header | Payload | | Header | Payload | | Header | Payload | | Header | Payload | | Header | Payload |
+--------+---------+ +--------+---------+ +--------+---------+ +--------+---------+ +--------+---------+ +--------+---------+
Figure 13: Encapsulation of a SNDU into a series of TS Packets Figure 13: Encapsulation of an SNDU into a series of TS Packets
6.1 SNDU Encapsulation 6.1 SNDU Encapsulation
When an Encapsulator has not previously sent a TS Packet for a When an Encapsulator has not previously sent a TS Packet for a
specific TS Logical Channel, or after an Idle period, it starts to specific TS Logical Channel, or after an Idle period, it starts to
send a SNDU in the first available TS Packet. This first TS Packet send an SNDU in the first available TS Packet. This first TS Packet
generated MUST carry a PUSI value of 1. It MUST also carry a Payload generated MUST carry a PUSI value of 1. It MUST also carry a Payload
Pointer value of zero indicating the SNDU starts in the first Pointer value of zero indicating the SNDU starts in the first
available byte of the TS Packet payload. available byte of the TS Packet payload.
The Encapsulation MUST ensure that all TS Packets set the MPEG-2 The Encapsulation MUST ensure that all TS Packets set the MPEG-2
Continuity Counter carried in the TS Packet header, according to Continuity Counter carried in the TS Packet header, according to
[ISO-MPEG]. This value MUST be incremented by one (modulo 16) for [ISO-MPEG2]. This value MUST be incremented by one (modulo 16) for
each successive fragment/complete SNDU sent using a TS Logical each successive fragment/complete SNDU sent using a TS Logical
Channel. Channel.
An Encapsulator MAY decide not to immediately send another SNDU, An Encapsulator MAY decide not to immediately send another SNDU,
even if space is available in a partially filled TS Packet. This even if space is available in a partially filled TS Packet. This
procedure is known as Padding (figure 11). It informs the Receiver procedure is known as Padding (figure 11). The End Indicator informs
that there are no more SNDUs in this TS Packet payload. The End the Receiver that there are no more SNDUs in this TS Packet payload.
Indicator is followed by zero or more unused bytes until the end of The End Indicator is followed by zero or more unused bytes until the
the TS Packet payload. All unused bytes MUST be set to the value of end of the TS Packet payload. All unused bytes MUST be set to the
0xFF, following current practice in MPEG-2 [ISO-DSMCC]. The Padding value of 0xFF, following current practice in MPEG-2 [ISO-DSMCC]. The
procedure trades decreased efficiency against improved latency. Padding procedure trades decreased efficiency against improved
latency.
Expires July 2005 [page 20] Expires July 2005 [page 21]
+-/------------+ +-/------------+
| SubNetwork | | SubNetwork |
| DU 3 | | DU 3 |
+-/------------+ +-/------------+
\ \ \ \
\ \ \ \
\ \ \ \
+--------+--------+--------+----------+ +--------+--------+--------+----------+
|MPEG-2TS| End of | 0xFFFF | Unused | |MPEG-2TS| End of | 0xFFFF | Unused |
| Header | SNDU 3 | | Bytes | | Header | SNDU 3 | | Bytes |
skipping to change at line 1003 skipping to change at line 1066
Figure 15: A TS Packet with the end of SNDU 1, followed by SNDU 2. Figure 15: A TS Packet with the end of SNDU 1, followed by SNDU 2.
6.2 Procedure for Padding and Packing 6.2 Procedure for Padding and Packing
Five possible actions may occur when an Encapsulator has completed Five possible actions may occur when an Encapsulator has completed
encapsulation of an SNDU: encapsulation of an SNDU:
(i) If the TS Packet has no remaining space, the Encapsulator (i) If the TS Packet has no remaining space, the Encapsulator
transmits this TS Packet. It starts transmission of the next SNDU in transmits this TS Packet. It starts transmission of the next SNDU in
a new TS Packet. (The standard rules [ISO-MPEG] require the header a new TS Packet. (The standard rules [ISO-MPEG2] require the header
of this new TS Packet to carry a PUSI value of 1, and a Payload of this new TS Packet to carry a PUSI value of 1, and a Payload
Pointer value of 0x00.) Pointer value of 0x00.)
Expires July 2005 [page 21] Expires July 2005 [page 22]
(ii) If the TS Packet carrying the final part of a SNDU has one byte (ii) If the TS Packet carrying the final part of an SNDU has one
of unused payload, the Encapsulator MUST place the value 0xFF in byte of unused payload, the Encapsulator MUST place the value 0xFF
this final byte, and transmit the TS Packet. This rule provides a in this final byte, and transmit the TS Packet. This rule provides a
simple mechanism to resolve the complex behaviour that may arise simple mechanism to resolve the complex behaviour that may arise
when the TS Packet has no PUSI set. To send another SNDU in the when the TS Packet has no PUSI set. To send another SNDU in the
current TS Packet, would otherwise require the addition of a Payload current TS Packet, would otherwise require the addition of a Payload
Pointer that would consume the last remaining byte of TS Packet Pointer that would consume the last remaining byte of TS Packet
payload. The behaviour follows similar practice for other MPEG-2 payload. The behaviour follows similar practice for other MPEG-2
payload types [ISO-DSMCC]. The Encapsulator MUST start transmission payload types [ISO-DSMCC]. The Encapsulator MUST start transmission
of the next SNDU in a new TS Packet. (The standard rules require the of the next SNDU in a new TS Packet. (The standard rules require the
header of this new TS Packet to carry a PUSI value of 1 and a header of this new TS Packet to carry a PUSI value of 1 and a
Payload Pointer value of 0x00.) Payload Pointer value of 0x00.)
(iii) If the TS Packet carrying the final part of a SNDU has exactly (iii) If the TS Packet carrying the final part of an SNDU has
two bytes of unused payload, and the PUSI was NOT already set, the exactly two bytes of unused payload, and the PUSI was NOT already
Encapsulator MUST place the value 0xFFFF in this final two bytes, set, the Encapsulator MUST place the value 0xFFFF in this final two
providing an End Indicator (section 4.3), and transmit the TS bytes, providing an End Indicator (section 4.3), and transmit the TS
Packet. This rule prevents fragmentation of the SNDU Length Field Packet. This rule prevents fragmentation of the SNDU Length Field
over two TS Packets. The Encapsulator MUST start transmission of the over two TS Packets. The Encapsulator MUST start transmission of the
next SNDU in a new TS Packet. (The standard rules require the header next SNDU in a new TS Packet. (The standard rules require the header
of this new TS Packet to carry a PUSI value of 1 and a Payload of this new TS Packet to carry a PUSI value of 1 and a Payload
Pointer value of 0x00.) Pointer value of 0x00.)
(iv) If the TS Packet has more than two bytes of unused payload, the (iv) If the TS Packet has more than two bytes of unused payload, the
Encapsulator MAY transmit this partially full TS Packet but MUST Encapsulator MAY transmit this partially full TS Packet but MUST
first place the value 0xFF in all remaining unused bytes (i.e. first place the value 0xFF in all remaining unused bytes (i.e.
setting an End Indicator followed by Padding). The Encapsulator MUST setting an End Indicator followed by Padding). The Encapsulator MUST
start transmission of the next SNDU in a new TS Packet. (The start transmission of the next SNDU in a new TS Packet. (The
standard rules [ISO-MPEG] require the header of this new TS Packet standard rules [ISO-MPEG2] require the header of this new TS Packet
to carry a PUSI value of 1 and a Payload Pointer value of 0x00.) to carry a PUSI value of 1 and a Payload Pointer value of 0x00.)
(v) If at least two bytes are available for payload data in the TS (v) If at least two bytes are available for SNDU data in the TS
Packet payload (i.e. three bytes if the PUSI was NOT previously set, Packet payload (i.e. three bytes if the PUSI was NOT previously set,
and two bytes if it was previously set), the Encapsulator MAY and two bytes if it was previously set), the Encapsulator MAY
encapsulate further queued PDUs, by starting the next SNDU in the encapsulate further queued PDUs, by starting the next SNDU in the
next available byte of the current TS Packet payload. The PUSI MUST next available byte of the current TS Packet payload. The PUSI MUST
be set. When the Encapsulator packs further SNDUs into a TS Packet be set. When the Encapsulator packs further SNDUs into a TS Packet
where the PUSI has NOT already been set, this requires the PUSI to where the PUSI has NOT already been set, this requires the PUSI to
be updated (set to 1) and an 8-bit Payload Pointer MUST be inserted be updated (set to 1) and an 8-bit Payload Pointer MUST be inserted
in the first byte directly following the TS Packet header. The value in the first byte directly following the TS Packet header. The value
MUST be set to the position of the byte following the end of the MUST be set to the position of the byte following the end of the
first SNDU in the TS Packet payload. If no further PDUs are first SNDU in the TS Packet payload. If no further PDUs are
available, an Encapsulator MAY wait for additional PDUs to fill the available, an Encapsulator MAY wait for additional PDUs to fill the
incomplete TS Packet. The maximum period of time an Encapsulator can incomplete TS Packet. The maximum period of time an Encapsulator can
wait, known as the Packing Threshold, MUST be bounded and SHOULD be wait, known as the Packing Threshold, MUST be bounded and SHOULD be
configurable in the Encapsulator. If sufficient additional PDUs are configurable in the Encapsulator. If sufficient additional PDUs are
NOT received to complete the TS Packet within the Packing Threshold, NOT received to complete the TS Packet within the Packing Threshold,
the Encapsulator MUST insert an End Indicator (using rule iv). the Encapsulator MUST insert an End Indicator (using rule iv).
Use of the Packing method (v) by an Encapsulator is optional, and Use of the Packing method (v) by an Encapsulator is optional, and
may be determined on a per-session, per-packet, or per-SNDU basis. may be determined on a per-session, per-packet, or per-SNDU basis.
Expires July 2005 [page 22] Expires July 2005 [page 23]
When a SNDU is less than the size of a TS Packet payload, a TS When an SNDU is less than the size of a TS Packet payload, a TS
Packet may be formed that carries a PUSI value of one and also an Packet may be formed that carries a PUSI value of one and also an
End Indicator (using rule iv). End Indicator (using rule iv).
Expires July 2005 [page 23] Expires July 2005 [page 24]
7. Receiver Processing 7. Receiver Processing
A Receiver tunes to a specific TS Multiplex and sets a receive A Receiver tunes to a specific TS Multiplex and sets a receive
filter to accept all TS Packets with a specific PID. These TS filter to accept all TS Packets with a specific PID. These TS
Packets are associated with a specific TS Logical Channel and are Packets are associated with a specific TS Logical Channel and are
reassembled to form a stream of SNDUs. A single Receiver may be reassembled to form a stream of SNDUs. A single Receiver may be
able to receive multiple TS Logical Channels, possibly using a range able to receive multiple TS Logical Channels, possibly using a range
of TS Multiplexes. In each case, reassembly MUST be performed of TS Multiplexes. In each case, reassembly MUST be performed
independently for each TS Logical Channel. To perform this independently for each TS Logical Channel. To perform this
skipping to change at line 1120 skipping to change at line 1183
Insufficient | +----+-----+ | Insufficient | +----+-----+ |
unused space | | PUSI set | MPEG-2 TS Error unused space | | PUSI set | MPEG-2 TS Error
or | \/ | or or | \/ | or
End Indicator| +----------+ | SNDU Error End Indicator| +----------+ | SNDU Error
| |Reassembly| | | |Reassembly| |
+--------| State |--------+ +--------| State |--------+
+----------+ +----------+
Figure 16: Receiver state transitions Figure 16: Receiver state transitions
Expires July 2005 [page 24] Expires July 2005 [page 25]
7.1.1 Idle State Payload Pointer Checking 7.1.1 Idle State Payload Pointer Checking
A Receiver in the Idle State MUST check the PUSI value in the header A Receiver in the Idle State MUST check the PUSI value in the header
of all received TS Packets. A PUSI value of 1 indicates the presence of all received TS Packets. A PUSI value of 1 indicates the presence
of a Payload Pointer. Following a loss of synchronisation, values of a Payload Pointer. Following a loss of synchronisation, values
between 0 and 181 are permitted, in which case the Receiver MUST between 0 and 181 are permitted, in which case the Receiver MUST
discard the number of bytes indicated by the Payload Pointer from discard the number of bytes indicated by the Payload Pointer
the start of the TS Packet payload, before leaving the Idle State. (counted from the first byte of the TS Packet payload field, and
It then enters the Reassembly State, and starts reassembly of a new excluding the PP field itself), before leaving the Idle State. It
then enters the Reassembly State, and starts reassembly of a new
SNDU at this point. SNDU at this point.
7.2 Processing of a Received SNDU 7.2 Processing of a Received SNDU
When in the Reassembly State, the Receiver reads a 2 byte SNDU When in the Reassembly State, the Receiver reads a 2 byte SNDU
Length Field from the TS Packet payload. If the value is less than Length Field from the TS Packet payload. If the value is less than
or equal to 4, or equal to 0xFFFF, the Receiver discards the Current or equal to 4, or equal to 0xFFFF, the Receiver discards the Current
SNDU and the remaining TS Packet payload and returns to the Idle SNDU and the remaining TS Packet payload and returns to the Idle
State. Receipt of an invalid Length Field is an error event and State. Receipt of an invalid Length Field is an error event and
SHOULD be recorded as an SNDU length error. SHOULD be recorded as an SNDU length error.
If the Length of the Current SNDU is greater than 4, the Receiver If the Length of the Current SNDU is greater than 4, the Receiver
accepts bytes from the TS Packet payload to the Current SNDU buffer accepts bytes from the TS Packet payload to the Current SNDU buffer
until either Length bytes in total are received, or the end of the until either Length bytes in total are received, or the end of the
TS Packet is reached (see also 7.2.1). When Current SNDU length TS Packet is reached (see also 7.2.1). When Current SNDU length
equals the value of the Length Field, the Receiver MUST calculate equals the value of the Length Field, the Receiver MUST calculate
and verify the CRC value (see 4.6). SNDUs that contain an invalid and verify the CRC value (see 4.6). SNDUs that contain an invalid
CRC value MUST be discarded. Mismatch of the CRC is an error event CRC value MUST be discarded. Mismatch of the CRC is an error event
and SHOULD be recorded as a CRC error. The under-lying physical-* and SHOULD be recorded as a CRC error. The under-lying physical-
layer processing (e.g. forward error correction coding) often layer processing (e.g. forward error correction coding) often
results in patterns of errors, rather than since bit errors, so the results in patterns of errors, rather than single bit errors, so the
Receiver needs to be robust to arbitrary patterns of corruption to Receiver needs to be robust to arbitrary patterns of corruption to
the TS Packet and payload, including potential corruption of the the TS Packet and payload, including potential corruption of the
PUSI, PP, and SNDU Length fields. Therefore, a Receiver SHOULD PUSI, PP, and SNDU Length fields. Therefore, a Receiver SHOULD
discard the remaining TS Packet payload (if any) following a CRC discard the remaining TS Packet payload (if any) following a CRC
mismatch and return to the Idle State. mismatch and return to the Idle State.
When the Destination Address is present (D=0), the Receiver accepts When the Destination Address is present (D=0), the Receiver accepts
SNDUs that match one of a set of addresses specified by the Receiver SNDUs that match one of a set of addresses specified by the Receiver
(this includes the NPA address of the Receiver, the NPA broadcast (this includes the NPA address of the Receiver, the NPA broadcast
address and any required multicast NPA addresses). The Receiver MUST address and any required multicast NPA addresses). The Receiver MUST
silently discard an SNDU with an unmatched address. silently discard an SNDU with an unmatched address.
After receiving a valid SNDU, the Receiver MUST check the Type Field After receiving a valid SNDU, the Receiver MUST check the Type Field
(and process any Type 1 Extension Headers). The SNDU payload is then (and process any Type 1 Extension Headers). The SNDU payload is then
passed to the next protocol layer specified. An SNDU with an unknown passed to the next protocol layer specified. An SNDU with an unknown
Type value < 1536 MUST be discarded. This error event SHOULD be Type value < 1536 MUST be discarded. This error event SHOULD be
recorded as a SNDU type error. recorded as an SNDU type error.
Expires July 2005 [page 26]
The Receiver then starts reassembly of the next SNDU. This MAY The Receiver then starts reassembly of the next SNDU. This MAY
directly follow the previously reassembled SNDU within the TS Packet directly follow the previously reassembled SNDU within the TS Packet
payload. payload.
Expires July 2005 [page 25]
(i) If the Current SNDU finishes at the end of a TS Packet payload, (i) If the Current SNDU finishes at the end of a TS Packet payload,
the Receiver MUST enter the Idle State. the Receiver MUST enter the Idle State.
(ii) If only one byte remains unprocessed in the TS Packet payload (ii) If only one byte remains unprocessed in the TS Packet payload
after completion of the Current SNDU, the Receiver MUST discard this after completion of the Current SNDU, the Receiver MUST discard this
final byte of TS Packet payload. It then enters the Idle State. It final byte of TS Packet payload. It then enters the Idle State. It
MUST NOT record an error when the value of the remaining byte is MUST NOT record an error when the value of the remaining byte is
identical to 0xFF. identical to 0xFF.
(iii) If two or more bytes of TS Packet payload data remain after (iii) If two or more bytes of TS Packet payload data remain after
completion of the Current SNDU, the Receiver accepts the next 2 completion of the Current SNDU, the Receiver accepts the next 2
bytes and examines if this is an End Indicator. When an End bytes and examines if this is an End Indicator. When an End
Indicator is received, a Receiver MUST silently discard the Indicator is received, a Receiver MUST silently discard the
remainder of the TS Packet payload and transition to the Idle State. remainder of the TS Packet payload and transition to the Idle State.
Otherwise this is the start of the next Packed SNDU, and the Otherwise this is the start of the next Packed SNDU and the Receiver
Receiver continues by processing this SNDU. continues by processing this SNDU (provided that the TS Packet has a
PUSI value of 1, see 7.2.1, otherwise the Receiver has detected a
delimiting error and MUST discard all remaining bytes in the TS
Packet payload and transitions to the Idle State).
7.2.1 Reassembly Payload Pointer Checking 7.2.1 Reassembly Payload Pointer Checking
A Receiver that has partially received a SNDU (in the Current SNDU A Receiver that has partially received an SNDU (in the Current SNDU
buffer) MUST check the PUSI value in the header of all subsequent TS buffer) MUST check the PUSI value in the header of all subsequent TS
Packets with the same PID (i.e. same TS Logical Channel). If it Packets with the same PID (i.e. same TS Logical Channel). If it
receives a TS Packet with a PUSI value of 1, it MUST then verify the receives a TS Packet with a PUSI value of 1, it MUST then verify the
Payload Pointer. If the Payload Pointer does NOT equal the number of Payload Pointer. If the Payload Pointer does NOT equal the number of
bytes remaining to complete the Current SNDU, i.e., the difference bytes remaining to complete the Current SNDU, i.e., the difference
between the SNDU Length field and the number of reassembled bytes, between the SNDU Length field and the number of reassembled bytes,
the Receiver has detected a delimiting error. the Receiver has detected a delimiting error.
Following a delimiting error, the Receiver MUST discard the Following a delimiting error, the Receiver MUST discard the
partially assembled SNDU (in the Current SNDU buffer), and SHOULD partially assembled SNDU (in the Current SNDU buffer), and SHOULD
record a reassembly error. It MUST then re-enter the Idle State. record a reassembly error. It MUST then re-enter the Idle State.
7.3 Other Error Conditions 7.3 Other Error Conditions
The Receiver SHOULD check the MPEG-2 Transport Error Indicator The Receiver SHOULD check the MPEG-2 Transport Error Indicator
carried in the TS Packet header [ISO-MPEG]. This flag indicates a carried in the TS Packet header [ISO-MPEG2]. This flag indicates a
transmission error for a TS Logical Channel. If the flag is set to a transmission error for a TS Logical Channel. If the flag is set to a
value of one, a transmission error event SHOULD be recorded. Any value of one, a transmission error event SHOULD be recorded. Any
partially received SNDU MUST be discarded. The Receiver then enters partially received SNDU MUST be discarded. The Receiver then enters
the Idle State. the Idle State.
The Receiver MUST check the MPEG-2 Continuity Counter carried in the The Receiver MUST check the MPEG-2 Continuity Counter carried in the
TS Packet header [ISO-MPEG]. If two (or more) successive TS Packets TS Packet header [ISO-MPEG2]. If two (or more) successive TS Packets
within the same TS Logical Channel carry the same Continuity Counter within the same TS Logical Channel carry the same Continuity Counter
Expires July 2005 [page 27]
value, the duplicate TS Packets MUST be silently discarded. If the value, the duplicate TS Packets MUST be silently discarded. If the
received value is NOT identical to that in the previous TS Packet, received value is NOT identical to that in the previous TS Packet,
and it does NOT increment by one for successive TS Packets (modulo and it does NOT increment by one for successive TS Packets (modulo
16), the Receiver has detected a continuity error. Any partially 16), the Receiver has detected a continuity error. Any partially
received SNDU MUST be discarded. A continuity counter error event received SNDU MUST be discarded. A continuity counter error event
SHOULD be recorded. The Receiver then enters the Idle State. SHOULD be recorded. The Receiver then enters the Idle State.
Expires July 2005 [page 26]
Note that an MPEG2-2 Transmission network is permitted to carry Note that an MPEG2-2 Transmission network is permitted to carry
duplicate TS Packets [ISO-MPEG], which are normally detected by the duplicate TS Packets [ISO-MPEG2], which are normally detected by the
MPEG-2 Continuity Counter. A Receiver that does not perform the MPEG-2 Continuity Counter. A Receiver that does not perform the
above Continuity Counter check, would accept duplicate copies of TS above Continuity Counter check, would accept duplicate copies of TS
Packets to the reassembly procedure. In most cases, the SNDU CRC-32 Packets to the reassembly procedure. In most cases, the SNDU CRC-32
integrity check will result in discard of these SNDUs, leading to integrity check will result in discard of these SNDUs, leading to
unexpected PDU loss, however in some cases, duplicate PDUs (fitting unexpected PDU loss, however in some cases, duplicate PDUs (fitting
into one TS Packet) could pass undetected to the next layer into one TS Packet) could pass undetected to the next layer
protocol. protocol.
Expires July 2005 [page 27] Expires July 2005 [page 28]
8. Summary 8. Summary
This document defines an Ultra Lightweight Encapsulation (ULE) to This document defines an Ultra Lightweight Encapsulation (ULE) to
perform efficient and flexible support for IPv4 and IPv6 network perform efficient and flexible support for IPv4 and IPv6 network
services over networks built upon the MPEG-2 Transport Stream (TS). services over networks built upon the MPEG-2 Transport Stream (TS).
The encapsulation is also suited to transport of other protocol The encapsulation is also suited to transport of other protocol
packets and bridged Ethernet frames. packets and bridged Ethernet frames.
ULE also provides an Extension Header format and defines an ULE also provides an Extension Header format and defines an
associated IANA registry for efficient and flexible support of both associated IANA registry for efficient and flexible support of both
mandatory and optional SNDU headers. This allows for future mandatory and optional SNDU headers. This allows for future
extension of the protocol, while providing backwards capability with extension of the protocol, while providing backwards compatibility
existing implementations. In particular, Optional Extension Headers with existing implementations. In particular, Optional Extension
may safely be ignored by Receiver drivers that do not implement Headers may safely be ignored by Receiver drivers that do not
them, or choose not to process them. implement them, or choose not to process them.
9. Acknowledgments 9. Acknowledgments
This draft is based on a previous draft authored by: Horst D. This draft is based on a previous draft authored by: Horst D.
Clausen, Bernhard Collini-Nocker, Hilmar Linder, and Gorry Clausen, Bernhard Collini-Nocker, Hilmar Linder, and Gorry
Fairhurst. The authors wish to thank the members of the ip-dvb Fairhurst. The authors wish to thank the members of the ip-dvb
mailing list for their input provided. In particular, the many mailing list for their input provided. In particular, the many
comments received from Patrick Cipiere, Wolgang Fritsche, Hilmar comments received from Art Allison, Carstsen Borman, Patrick
Linder, Alain Ritoux, and William Stanislaus. Alain also provided Cipiere, Wolgang Fritsche, Hilmar Linder, Alain Ritoux, and
the original examples of usage. William Stanislaus. Alain also provided the original examples of
usage.
Expires July 2005 [page 28] Expires July 2005 [page 29]
10. Security Considerations 10. Security Considerations
The security considerations for ULE resemble those that arise when The security considerations for ULE resemble those that arise when
the existing Multi-Protocol Encapsulation (MPE) is used. ULE does the existing Multi-Protocol Encapsulation (MPE) is used. ULE does
not add specific new threats that will impact the security of the not add specific new threats that will impact the security of the
general Internet. general Internet.
There is a known security issue with un-initialised stuffing bytes. There is a known security issue with un-initialised stuffing bytes.
In ULE, these bytes are set to 0xFF (normal practice in MPEG-2). In ULE, these bytes are set to 0xFF (normal practice in MPEG-2).
skipping to change at line 1288 skipping to change at line 1357
exposes the traffic to potentially undetected corruption while being exposes the traffic to potentially undetected corruption while being
processed by the Encapsulator and/or Receiver. processed by the Encapsulator and/or Receiver.
There is a potential security issue when a Receiver receives a PDU There is a potential security issue when a Receiver receives a PDU
with two length fields: The Receiver would need to validate the with two length fields: The Receiver would need to validate the
actual length and the Length Field and ensure that inconsistent actual length and the Length Field and ensure that inconsistent
values are not propagated by the network. In direct encapsulation of values are not propagated by the network. In direct encapsulation of
IPv4/IPv6 in ULE, this is avoided by including only one SNDU Length IPv4/IPv6 in ULE, this is avoided by including only one SNDU Length
Field. However, this issue still arises in bridged LLC frames, and Field. However, this issue still arises in bridged LLC frames, and
frames with a LLC Length greater than the SNDU payload size MUST be frames with a LLC Length greater than the SNDU payload size MUST be
discarded, and a SNDU payload length error SHOULD be recorded. discarded, and an SNDU payload length error SHOULD be recorded.
A ULE Mandatory Extension Header may in future be used to define a A ULE Mandatory Extension Header may in future be used to define a
method to perform link encryption of the SNDU payload. This is as an method to perform link encryption of the SNDU payload. This is as an
additional security mechanism to IP, transport or application layer additional security mechanism to IP, transport or application layer
security - not a replacement [ID-ipdvb-arch]. The approach is security - not a replacement [ID-ipdvb-arch]. The approach is
generic and decouples the encapsulation from future security generic and decouples the encapsulation from future security
extensions. The operation provides functions that resemble those extensions. The operation provides functions that resemble those
currently used with the MPE encapsulation. currently used with the MPE encapsulation.
Additional security control fields may be provided as a part of this Additional security control fields may be provided as a part of this
link encryption Extension Header, e.g. to associate an SNDU with one link encryption Extension Header, e.g. to associate an SNDU with one
of a set of Security Association (SA) parameters. As a part of the of a set of Security Association (SA) parameters. As a part of the
encryption process, it may also be desirable to authenticate encryption process, it may also be desirable to authenticate
some/all of the SNDU headers. The method of encryption and the way some/all of the SNDU headers. The method of encryption and the way
in which keys are exchanged is beyond the scope of this in which keys are exchanged is beyond the scope of this
specification, as also are the definition of the SA format and that specification, as also are the definition of the SA format and that
of the related encryption keys. of the related encryption keys.
Expires July 2005 [page 29] Expires July 2005 [page 30]
11. References 11. References
11.1 Normative References 11.1 Normative References
[ISO-MPEG] ISO/IEC DIS 13818-1 "Information technology -- Generic [ISO-MPEG2] ISO/IEC IS 13818-1 "Information technology -- Generic
coding of moving pictures and associated audio information: coding of moving pictures and associated audio information -- Part
Systems", International Standards Organisation (ISO). 1: Systems", International Standards Organisation (ISO), 2000.
[RFC2026] Bradner, S., "The Internet Standards Process - Revision
3", BCP 9, RFC 2026, BCP 9, 1996.
[RFC2119] Bradner, S., "Key Words for Use in RFCs to Indicate [RFC2119] Bradner, S., "Key Words for Use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, 1997. Requirement Levels", BCP 14, RFC 2119, 1997.
[RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78, RFC [RFC3667] Bradner, S., "IETF Rights in Contributions", BCP 78, RFC
3667, February 2004. 3667, February 2004.
[RFC3668] Bradner, S., "Intellectual Property Rights in IETF [RFC3668] Bradner, S., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3668, February 2004. Technology", BCP 79, RFC 3668, February 2004.
[RFC1112] Deering, S., "Host extensions for IP multicasting", STD 5,
RFC 1112, August 1989.
[RFC2464] Crawford, M., "Transmission of IPv6 Packets over Ethernet
Networks", RFC 2464, December 1998.
11.2 Informative References 11.2 Informative References
[ID-ipdvb-arch] "Requirements for transmission of IP datagrams over [ID-ipdvb-arch] "Requirements for transmission of IP datagrams over
MPEG-2 networks", Internet Draft, Work in Progress. MPEG-2 networks", Internet Draft, Work in Progress.
[ATSC] A/53, "ATSC Digital Television Standard", Advanced Television [ATSC] A/53, "ATSC Digital Television Standard", Advanced Television
Systems Committee (ATSC), Doc. A/53 Rev.C, 2004 Systems Committee (ATSC), Doc. A/53 Rev.C, 2004
[ATSC-DAT] A/90, "ATSC Data Broadcast Standard", Advanced Television [ATSC-DAT] A/90, "ATSC Data Broadcast Standard", Advanced Television
Systems Committee (ATSC), Doc. A/090, 2000. Systems Committee (ATSC), Doc. A/090, 2000.
[ATSC-DATG] A/91, "Recommended Practice: Implementation Guidelines [ATSC-DATG] A/91, "Recommended Practice: Implementation Guidelines
for the ATSC Data Broadcast Standard", Advanced Television Systems for the ATSC Data Broadcast Standard", Advanced Television Systems
Committee (ATSC), Doc. A/91, 2001. Committee (ATSC), Doc. A/91, 2001.
[ATSC-G] A/54, "Guide to the use of the ATSC Digital Television [ATSC-G] A/54, "Guide to the use of the ATSC Digital Television
Standard", Advanced Television Systems Committee (ATSC), Doc. A/54, Standard", Advanced Television Systems Committee (ATSC), Doc. A/54,
1995. 1995.
[ATSC-PSIP-TC] A/65A, "Program and System Information Protocol for [ATSC-PSIP-TC] A/65B Program and System Information Protocol for
Terrestrial Broadcast and Cable", Advanced Television Systems Terrestrial Broadcast and Cable", Advanced Television Systems
Committee (ATSC), Doc. A/65A, 23 Dec 1997, Rev. A, 2000. Committee The(ATSC), Doc. A/65B, 18 March 2003.
[ATSC-S] A/80, "Modulation and Coding Requirements for Digital TV [ATSC-S] A/80, "Modulation and Coding Requirements for Digital TV
(DTV) Applications over Satellite", Advanced Television Systems (DTV) Applications over Satellite", Advanced Television Systems
Committee (ATSC), Doc. A/80, 1999. Committee (ATSC), Doc. A/80, 1999.
[CLC99] Clausen, H., Linder, H., and Collini-Nocker, B., "Internet Expires July 2005 [page 31]
over Broadcast Satellites", IEEE Commun. Mag. 1999, pp.146-151. [DIX] Digital Equipment Corp, Intel Corp, Xerox Corp, "Ethernet
Local Area Network Specification" Version 2.0, November 1982.
Expires July 2005 [page 30]
[ETSI-DAT] EN 301 192 "Specifications for Data Broadcasting", [ETSI-DAT] EN 301 192 "Specifications for Data Broadcasting",
European Telecommunications Standards Institute (ETSI). European Telecommunications Standards Institute (ETSI).
[ETSI-DVBC] EN 300 800 "Digital Video Broadcasting (DVB); DVB [ETSI-DVBC] EN 300 800 "Digital Video Broadcasting (DVB); DVB
interaction channel for Cable TV distribution systems (CATV)", interaction channel for Cable TV distribution systems (CATV)",
European Telecommunications Standards Institute (ETSI). European Telecommunications Standards Institute (ETSI).
[ETSI-DVBS] EN 301 421 "Digital Video Broadcasting (DVB); Modulation [ETSI-DVBS] EN 301 421 "Digital Video Broadcasting (DVB); Modulation
and Coding for DBS satellite systems at 11/12 GHz", European and Coding for DBS satellite systems at 11/12 GHz", European
Telecommunications Standards Institute (ETSI). Telecommunications Standards Institute (ETSI).
[ETSI-DVBT] EN 300 744 "Digital Video Broadcasting (DVB); Framing [ETSI-DVBT] EN 300 744 "Digital Video Broadcasting (DVB); Framing
structure, channel coding and modulation for digital terrestrial structure, channel coding and modulation for digital terrestrial
television (DVB-T)", European Telecommunications Standards Institute television (DVB-T)", European Telecommunications Standards Institute
(ETSI). (ETSI).
[ETSI-RCS] ETSI 301 791 "Digital Video Broadcasting (DVB); [ETSI-RCS] ETSI 301 791 "Digital Video Broadcasting (DVB);
Interaction Channel for Satellite Distribution Systems", European Interaction Channel for Satellite Distribution Systems", European
Telecommunications Standards Institute (ETSI). Telecommunications Standards Institute (ETSI).
[IEEE-802.3] IEEE 802.3 "Local and metropolitan area networks:
Specific requirements Part 3: Carrier sense multiple access with
collision detection (CSMA/CD) access method and physical layer
specifications", IEEE Computer Society, (also ISO/IEC 8802-3).
[ISO-DSMCC] ISO/IEC IS 13818-6 "Information technology -- Generic [ISO-DSMCC] ISO/IEC IS 13818-6 "Information technology -- Generic
coding of moving pictures and associated audio information -- Part coding of moving pictures and associated audio information -- Part
6: Extensions for DSM-CC", International Standards Organisation 6: Extensions for DSM-CC", International Standards Organisation
(ISO). (ISO).
[ITU-I363] ITU-T I.363.5 B-ISDN ATM Adaptation Layer Specification [ISO-8802-2] ISO/IEC 8802.2 "Logical Link Control", International
Type AAL5, International Standards Organisation (ISO), 1996. Standards Organisation (ISO), 1998.
[LLC] "IEEE Logical Link Control" (ANSI/IEEE Std 802.2/ ISO 8802.2),
1985.
[RFC3077] E. Duros, W. Dabbous, H. Izumiyama, Y. Zhang, "A Link [RFC3077] E. Duros, W. Dabbous, H. Izumiyama, Y. Zhang, "A Link
Layer Tunneling Mechanism for Unidirectional Links", RFC3077, Layer Tunneling Mechanism for Unidirectional Links", RFC3077,
Proposed Standard, 2001. Proposed Standard, 2001.
[RFC3309] Stone, J., R. Stewart, D. Otis. "Stream Control [RFC3309] Stone, J., R. Stewart, D. Otis. "Stream Control
Transmission Protocol (SCTP) Checksum Change". RFC3095, Proposed Transmission Protocol (SCTP) Checksum Change". RFC3095, Proposed
Standard, 2001. Standard, 2001.
[RFC3819] Karn, P., Bormann, C., Fairhurst, G., Grossman, D., Expires July 2005 [page 32]
Ludwig, R., Mahdavi, J., Montenegro, G., Touch, J., and L. Wood,
"Advice for Internet Subnetwork Designers", BCP 89, RFC 3819, July
2004.
Expires July 2005 [page 31]
12. Authors' Addresses 12. Authors' Addresses
Godred Fairhurst Godred Fairhurst
Department of Engineering Department of Engineering
University of Aberdeen University of Aberdeen
Aberdeen, AB24 3UE Aberdeen, AB24 3UE
UK UK
Email: gorry@erg.abdn.ac.uk Email: gorry@erg.abdn.ac.uk
Web: http://www.erg.abdn.ac.uk/users/Gorry Web: http://www.erg.abdn.ac.uk/users/Gorry
Bernhard Collini-Nocker Bernhard Collini-Nocker
Department of Scientific Computing Department of Scientific Computing
University of Salzburg University of Salzburg
Jakob Haringer Str. 2 Jakob Haringer Str. 2
5020 Salzburg 5020 Salzburg
Austria Austria
Email: bnocker@cosy.sbg.ac.at Email: bnocker@cosy.sbg.ac.at
Web: http://www.scicomp.sbg.ac.at/ Web: http://www.scicomp.sbg.ac.at/
Expires July 2005 [page 32] Expires July 2005 [page 33]
13. IPR Notices 13. IPR Notices
13.1 Intellectual Property Statement 13.1 Intellectual Property Statement
The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
Intellectual Property Rights or other rights that might be claimed Intellectual Property Rights or other rights that might be claimed
to pertain to the implementation or use of the technology described to pertain to the implementation or use of the technology described
in this document or the extent to which any license under such in this document or the extent to which any license under such
rights might or might not be available; nor does it represent that rights might or might not be available; nor does it represent that
it has made any independent effort to identify any such rights. it has made any independent effort to identify any such rights.
skipping to change at line 1469 skipping to change at line 1538
THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED THE INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE. WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
14. Copyright Statement 14. Copyright Statement
Copyright (C) The Internet Society (2004). This document is Copyright (C) The Internet Society (2004). This document is
subject to the rights, licenses and restrictions contained in subject to the rights, licenses and restrictions contained in
BCP 78, and except as set forth therein, the authors retain all BCP 78, and except as set forth therein, the authors retain all
their rights. their rights.
Expires July 2005 [page 33] Expires July 2005 [page 34]
15. IANA Considerations 15. IANA Considerations
This document will require IANA involvement. This document will require IANA involvement.
The ULE Next-Header type field defined in this document requires The ULE Next-Header type field defined in this document requires
creation of a registry: creation of a registry:
ULE Next-Header registry ULE Next-Header registry
This registry allocates values 0-512 (decimal). This registry allocates values 0-511 (decimal).
15.1 IANA Guidelines 15.1 IANA Guidelines
The following contains the IANA guidelines for management of the ULE The following contains the IANA guidelines for management of the ULE
Next-Header registry. This registry allocates values 0-512 decimal Next-Header registry. This registry allocates values 0-511 decimal
(0x0000-0x01FF, hexadecimal). It MUST NOT allocate values greater (0x0000-0x01FF, hexadecimal). It MUST NOT allocate values greater
than 0x01FF (decimal). than 0x01FF (decimal).
It subdivides the Next-Header registry in the following way: It subdivides the Next-Header registry in the following way:
1) 0-255 (decimal) IANA assigned values indicating Mandatory 1) 0-255 (decimal) IANA assigned values indicating Mandatory
Extension Headers (or link-dependent type fields) for ULE, Extension Headers (or link-dependent type fields) for ULE,
requiring expert review leading to prior issue of an IETF RFC. requiring expert review leading to prior issue of an IETF RFC.
This specification must define the value, and the name associated This specification MUST define the value, and the name associated
with the Extension Header. It must also define the need for the with the Extension Header, together with the procedure for
extension and the intended use. The size of the Extension Header processing the Extension Header. It MUST also define the need for
must also be specified. the extension and the intended use. The total size of the
Extension Header MUST be specified.
Assignments made in this document: Assignments made in this document:
Type Name Reference Type Name Reference
0: Test-SNDU Section 4.7.4. 0: Test-SNDU Section 4.7.4.
1: Bridged-SNDU Section 4.7.5. 1: Bridged-SNDU Section 4.7.5.
2) 256-511 (decimal) IANA assigned values indicating Optional 2) 256-511 (decimal) IANA assigned values indicating Optional
Extension Headers for ULE, requiring expert review leading to Extension Headers for ULE, requiring expert review leading to
prior issue of an IETF RFC. This specification must define the prior issue of an IETF RFC. This specification MUST define the
value, and the name associated with the Extension Header. The value, and the name associated with the Extension Header, together
entry must specify range of allowable H-LEN values that are with the procedure for processing the Extension Header. The entry
permitted (in the range 1-5). It must also define the need for the MUST specify range of allowable H-LEN values that are permitted
extension and the intended use. (in the range 1-5). It MUST also define the need for the extension
and the intended use.
Assignments made in this document: Assignments made in this document:
Type Name H-LEN Reference Type Name H-LEN Reference
256: Extension-Padding 1-5 Section 5. 256: Extension-Padding 1-5 Section 5.
Expires July 2005 [page 34] Expires July 2005 [page 35]
ANNEXE A: Informative Appendix - SNDU Packing Examples
ANNEX A: Informative Appendix - SNDU Packing Examples
This appendix provides some examples of use. The appendix is This appendix provides some examples of use. The appendix is
informative. It does not provide a description of the protocol. The informative. It does not provide a description of the protocol. The
examples provide the complete TS Packet sequence for some sample examples provide the complete TS Packet sequence for some sample
encapsulated IP packets. encapsulated IP packets.
The specification of the TS Packet header operation and field values The specification of the TS Packet header operation and field values
is provided in [ISO-MPEG]. The specification of ULE is provided in is provided in [ISO-MPEG2]. The specification of ULE is provided in
the body of this document. the body of this document.
The key below is provided for the following examples. The key below is provided for the following examples.
HDR 4B TS Packet Header HDR 4B TS Packet Header
PUSI Payload Unit Start Indicator PUSI Payload Unit Start Indicator
PP Payload Pointer PP Payload Pointer
*** TS Packet Payload Pointer (PP) *** TS Packet Payload Pointer (PP)
Example A.1: Two 186B PDUs. Example A.1: Two 186B PDUs.
SNDU A is 200 bytes (including destination MAC address) SNDU A is 200 bytes (including the ULE destination NPA address)
SNDU B is 200 bytes (including destination MAC address) SNDU B is 200 bytes (including the ULE destination NPA address)
The sequence comprises 3 TS Packets: The sequence comprises 3 TS Packets:
SNDU SNDU
PP=0 Length PP=0 Length
+-----+------+------+------+- -+------+ +-----+------+------+------+- -+------+
| HDR | 0x00 | 0x00 | 0xC4 | ... | A182 | | HDR | 0x00 | 0x00 | 0xC4 | ... | A182 |
+-----+----*-+-*----+------+- -+------+ +-----+----*-+-*----+------+- -+------+
PUSI=1 * * PUSI=1 * *
***** *****
skipping to change at line 1567 skipping to change at line 1639
PUSI=1 * * PUSI=1 * *
************************* *************************
End Stuffing End Stuffing
CRC for A Indicator Bytes CRC for A Indicator Bytes
+-----+------+- -+------+----+----+- -+----+ +-----+------+- -+------+----+----+- -+----+
| HDR | B166 | ... | B199 |0xFF|0xFF| ... |0xFF| | HDR | B166 | ... | B199 |0xFF|0xFF| ... |0xFF|
+-----+------+- -+------+----+----+- -+----+ +-----+------+- -+------+----+----+- -+----+
PUSI=0 PUSI=0
Expires July 2005 [page 35] Expires July 2005 [page 36]
Example A.2: Usage of last byte in a TS-Packet Example A.2: Usage of last byte in a TS-Packet
SNDU A is 183 bytes SNDU A is 183 bytes
SNDU B is 182 bytes SNDU B is 182 bytes
SNDU C is 181 bytes SNDU C is 181 bytes
SNDU D is 185 bytes SNDU D is 185 bytes
The sequence comprises 4 TS Packets: The sequence comprises 4 TS Packets:
SNDU SNDU
skipping to change at line 1604 skipping to change at line 1676
| HDR | 0x00 | 0x00 | 0x61 | ... | C180 | 0x00 | 0x65 | | HDR | 0x00 | 0x00 | 0x61 | ... | C180 | 0x00 | 0x65 |
+-----+---*--+-*----+------+- -+------+------+------+ +-----+---*--+-*----+------+- -+------+------+------+
PUSI=1 * * PUSI=1 * *
****** Unused ****** Unused
byte byte
+-----+------+- -+------+------+ +-----+------+- -+------+------+
| HDR | D002 | ... | D184 | 0xFF | | HDR | D002 | ... | D184 | 0xFF |
+-----+------+- -+------+------+ +-----+------+- -+------+------+
PUSI=0 PUSI=0
Expires July 2005 [page 36] Expires July 2005 [page 37]
Example A.3: Large SNDUs Example A.3: Large SNDUs
SNDU A is 732 bytes SNDU A is 732 bytes
SNDU B is 284 bytes SNDU B is 284 bytes
The sequence comprises 6 TS Packets: The sequence comprises 6 TS Packets:
SNDU SNDU
PP=0 Length PP=0 Length
+-----+------+------+------+- -+------+ +-----+------+------+------+- -+------+
skipping to change at line 1650 skipping to change at line 1722
+-----+------+- -+------+ +-----+------+- -+------+
PUSI=0 PUSI=0
End Stuffing End Stuffing
Indicator Bytes Indicator Bytes
+-----+------+- -+------+------+------+- -+------+ +-----+------+- -+------+------+------+- -+------+
| HDR | B186 | ... | B283 | 0xFF | 0xFF | ... | 0xFF | | HDR | B186 | ... | B283 | 0xFF | 0xFF | ... | 0xFF |
+-----+------+- -+------+------+------+- -+------+ +-----+------+- -+------+------+------+- -+------+
PUSI=0 PUSI=0
Expires July 2005 [page 37] Expires July 2005 [page 38]
Example A.4: Packing of SNDUs Example A.4: Packing of SNDUs
SNDU A is 200 bytes SNDU A is 200 bytes
SNDU B is 60 bytes SNDU B is 60 bytes
SNDU C is 60 bytes SNDU C is 60 bytes
The sequence comprises two TS Packets: The sequence comprises two TS Packets:
SNDU SNDU
PP=0 Length PP=0 Length
skipping to change at line 1691 skipping to change at line 1763
+ ... | B59 | 0x00 | 0x38 |...| C59 | 0xFF | 0xFF |...| 0xFF | + ... | B59 | 0x00 | 0x38 |...| C59 | 0xFF | 0xFF |...| 0xFF |
+ -+------+-+----+------+ -+------+-+----+------+- -+------+ + -+------+-+----+------+ -+------+-+----+------+- -+------+
+ + + + + + + + + +
+ + ++++++++ + + + ++++++++ +
+ + + + + + + +
++++++++++++++++ ++++++++++++++++++++++ ++++++++++++++++ ++++++++++++++++++++++
*** TS Packet Payload Pointer (PP) *** TS Packet Payload Pointer (PP)
+++ ULE Length Indicator +++ ULE Length Indicator
Expires July 2005 [page 38] Expires July 2005 [page 39]
Example A.5: Three 44B PDUs. Example A.5: Three 44B PDUs.
SNDU A is 52 bytes (no destination MAC address) SNDU A is 52 bytes (no ULE destination NPA address)
SNDU B is 52 bytes (no destination MAC address) SNDU B is 52 bytes (no ULE destination NPA address)
SNDU C is 52 bytes (no destination MAC address) SNDU C is 52 bytes (no ULE destination NPA address)
The sequence comprises 1 TS Packet: The sequence comprises 1 TS Packet:
SNDU SNDU
PP=0 Length PP=0 Length
+-----+------+------+------+- -+-----+------+-----+- -+-----+- +-----+------+------+------+- -+-----+------+-----+- -+-----+-
| HDR | 0x00 | 0x80 | 0x34 | ... | A51 |0x80 | 0x34 | ... | B51 | .. | HDR | 0x00 | 0x80 | 0x34 | ... | A51 |0x80 | 0x34 | ... | B51 | ..
+-----+----*-+-*----+------+- -+-----+-*----+-----+- -+-----+- +-----+----*-+-*----+------+- -+-----+-*----+-----+- -+-----+-
PUSI=1 * * PUSI=1 * *
***** *****
End Stuffing End Stuffing
Indicator bytes Indicator bytes
-----+------+- -+-----+---------+- -+------+ -----+------+- -+-----+---------+- -+------+
... 0x80 | 0x34 | ... | C51 |0xFF|0xFF| | 0xFF | ... 0x80 | 0x34 | ... | C51 |0xFF|0xFF| | 0xFF |
-*---+------+- -+-----+---------+- -+------+ -*---+------+- -+-----+---------+- -+------+
Expires July 2005 [page 39] Expires July 2005 [page 40]
ANNEXE B: Informative Appendix - SNDU Encapsulation ANNEX B: Informative Appendix - SNDU Encapsulation
An example of ULE encapsulation carrying an ICMPv6 packet generated An example of ULE encapsulation carrying an ICMPv6 packet generated
by ping6. by ping6.
ULE SNDU Length : 63 decimal ULE SNDU Length : 63 decimal
D-bit value : 0 (NPA Present) D-bit value : 0 (NPA destination address present)
ULE Protocol Type : 0x86dd (IPv6) ULE Protocol Type : 0x86dd (IPv6)
Destination ULE NPA Address: 00:01:02:03:04:05 Destination ULE NPA Address: 00:01:02:03:04:05
ULE CRC32 : 0x4709a744 ULE CRC32 : 0x4709a744
Source IPv6: 2001:660:3008:1789::5 Source IPv6: 2001:660:3008:1789::5
Destination IPv6: 2001:660:3008:1789::6 Destination IPv6: 2001:660:3008:1789::6
SNDU contents (including CRC-32): SNDU contents (including CRC-32):
0000: 00 3f 86 dd 00 01 02 03 04 05 60 00 00 00 00 0d 0000: 00 3f 86 dd 00 01 02 03 04 05 60 00 00 00 00 0d
0016: 3a 40 20 01 06 60 30 08 17 89 00 00 00 00 00 00 0016: 3a 40 20 01 06 60 30 08 17 89 00 00 00 00 00 00
0032: 00 05 20 01 06 60 30 08 17 89 00 00 00 00 00 00 0032: 00 05 20 01 06 60 30 08 17 89 00 00 00 00 00 00
0048: 00 06 80 00 9d 8c 06 38 00 04 00 00 00 00 00 47 0048: 00 06 80 00 9d 8c 06 38 00 04 00 00 00 00 00 47
0064: 09 a7 44 0064: 09 a7 44
Expires July 2005 [page 40] Expires July 2005 [page 41]
[RFC EDITOR NOTE: [RFC EDITOR NOTE:
This section must be deleted prior to publication] This section must be deleted prior to publication]
DOCUMENT HISTORY DOCUMENT HISTORY
Draft 00 Draft 00
This draft is intended as a study item for proposed future work by This draft is intended as a study item for proposed future work by
the IETF in this area. Comments relating to this document will be the IETF in this area. Comments relating to this document will be
gratefully received by the author(s) and the ip-dvb mailing list at: gratefully received by the author(s) and the ip-dvb mailing list at:
skipping to change at line 1759 skipping to change at line 1831
-------------------------------------------------------------------- --------------------------------------------------------------------
DRAFT 01 (Protocol update) DRAFT 01 (Protocol update)
* Padding sequence modified to 0xFFFF, this change aligns with other * Padding sequence modified to 0xFFFF, this change aligns with other
usage by MPEG-2 streams. Treatment remains the same as specified for usage by MPEG-2 streams. Treatment remains the same as specified for
ULE. ULE.
* SDNU Format updated to include R-bit (reserved). * SDNU Format updated to include R-bit (reserved).
* Procedure for TS Packet carrying the final part of a SNDU with * Updated procedure for TS Packet carrying the final part of an SNDU
either less than two bytes of unused payload updated. with either less than two bytes of unused payload updated.
* A Receiver MUST silently discard the remainder of a TS Packet * A Receiver MUST silently discard the remainder of a TS Packet
payload when two or less bytes remain unprocessed following the end payload when two or less bytes remain unprocessed following the end
of a SNDU, irrespective of the PUSI value in the received TS Packet. of an SNDU, irrespective of the PUSI value in the received TS
It MUST NOT record an error when the value of the remaining byte(s) Packet. It MUST NOT record an error when the value of the remaining
is identical to 0xFF or 0xFFFF. The Receiver MUST then wait for a byte(s) is identical to 0xFF or 0xFFFF. The Receiver MUST then wait
TS Packet with a PUSI value set to 1. for a TS Packet with a PUSI value set to 1.
* Payload Pointer description updated. * Payload Pointer description updated.
* CRC Calculation added. * CRC Calculation added.
* Decapsulator processing revised. * Decapsulator processing revised.
* Type field split into two. * Type field split into two.
* References updated. * References updated.
* Security considerations added (first draft). * Security considerations added (first draft).
* Appendix added with examples. * Appendix added with examples.
-------------------------------------------------------------------- --------------------------------------------------------------------
Expires July 2005 [page 41] Expires July 2005 [page 42]
DRAFT - 02 (Improvement of clarity) DRAFT - 02 (Improvement of clarity)
* Corrected CRC-32 to follow standard practice in DSM-CC. * Corrected CRC-32 to follow standard practice in DSM-CC.
* Removed LLC frame type, now redundant by Bridge-Type (==1) * Removed LLC frame type, now redundant by Bridge-Type (==1)
* Defined D-bit to use the reserved bit field (R ) - Gorry, Alain, * Defined D-bit to use the reserved bit field (R ) - Gorry, Alain,
Bernhard Bernhard
* Changes to description of minimum payload length. Gorry * Changes to description of minimum payload length. Gorry
skipping to change at line 1836 skipping to change at line 1908
sections, since this is not a concern for deployment: Length field sections, since this is not a concern for deployment: Length field
usage and padding initialisation. usage and padding initialisation.
* Changed wording: All multi-byte values in ULE (including Length, * Changed wording: All multi-byte values in ULE (including Length,
Type, and Destination fields) are transmitted in network byte order Type, and Destination fields) are transmitted in network byte order
(most significant byte first). old NiT from Alain, now fixed. (most significant byte first). old NiT from Alain, now fixed.
* Frame byte size in diagrams now updated to -standard- format, and * Frame byte size in diagrams now updated to -standard- format, and
D bit action corrected, as requested by Alain. D bit action corrected, as requested by Alain.
Expires July 2005 [page 42] Expires July 2005 [page 43]
* Frame format diagrams, redrawn to 32-bit format below: * Frame format diagrams, redrawn to 32-bit format below:
0 1 2 3 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 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
* Additional diagram requested by Alain for D=0 bridging (added, and * Additional diagram requested by Alain for D=0 bridging (added, and
subsequent figures renumbered). subsequent figures renumbered).
* Diagrams of encapsulation process, redrawn for clarity (no change * Diagrams of encapsulation process, redrawn for clarity (no change
to meaning). Gorry. to meaning). Gorry.
skipping to change at line 1886 skipping to change at line 1958
* Revised CC processing at Encapsulator (B C-N/GF/A.Allison) * Revised CC processing at Encapsulator (B C-N/GF/A.Allison)
* Revised CC processing at Receiver (from List: A.Allison; et al ) * Revised CC processing at Receiver (from List: A.Allison; et al )
* Corrections to length/PP field in Examples (M Sooriyabandara, * Corrections to length/PP field in Examples (M Sooriyabandara,
Alain) Alain)
* Corrections to pointer in Example 3 SNDU C (M Jose-Montpetit) * Corrections to pointer in Example 3 SNDU C (M Jose-Montpetit)
* Section 4.5 only SHARED routed links require D=0 * Section 4.5 only SHARED routed links require D=0
* Packing Threshold defined * Packing Threshold defined
* Next-Layer-Header defined (Now called Next-Header) * Next-Layer-Header defined (Now called Next-Header)
* Addition of Appendix B (to aide verification of SNDFU format) * Addition of Appendix B (to aide verification of SNDFU format)
Expires July 2005 [page 43] Expires July 2005 [page 44]
Working Group ID rev 01 Working Group ID rev 01
Issues addressed: Issues addressed:
* Typographical * Typographical
* Types > 1500 should be passed to the next higher protocol (Hilmar) * Types > 1500 should be passed to the next higher protocol (Hilmar)
* The second part of the Type space corresponds to the values 1500 * The second part of the Type space corresponds to the values 1500
COMMENT: ~Range should be 1536 Decimal Decimal to 0xFFFF. COMMENT: ~Range should be 1536 Decimal Decimal to 0xFFFF.
* IANA has already defined IP and IPv6 types - corrected text! * IANA has already defined IP and IPv6 types - corrected text!
Added more security considerations (-01d). Added more security considerations (-01d).
* Should we allow an Adaptation Field within ULE (request for DVB- * Should we allow an Adaptation Field within ULE (request for DVB-
skipping to change at line 1926 skipping to change at line 1998
Correction of figure numbering. Correction of figure numbering.
Correction to capitalisation in Transport Stream definition of fields Correction to capitalisation in Transport Stream definition of fields
Inserted space character after 1536 in line 2 of 4.4.2 Inserted space character after 1536 in line 2 of 4.4.2
Replaced } with ] after ISO_DSMCC Replaced } with ] after ISO_DSMCC
Replace reference to section 6.3 with section 7.3 at end of section Replace reference to section 6.3 with section 7.3 at end of section
4.6. 4.6.
Reference in 4.7.4 was changed to refer to figure 7 (not 6). Reference in 4.7.4 was changed to refer to figure 7 (not 6).
Note added after figure 9. Note added after figure 9.
Expires July 2005 [page 44] Expires July 2005 [page 45]
Working Group ID rev 03 Working Group ID rev 03
Changes with this revision of the document: Changes with this revision of the document:
(i) The worked hexadecimal example in the annexe was reworked to (i) The worked hexadecimal example in the annexe was reworked to
include a valid MAC address for an IPv6 unicast packet. - include a valid MAC address for an IPv6 unicast packet. -
(BCN) (BCN)
(ii) The IANA procedures revised, based on inputs from IANA to (ii) The IANA procedures revised, based on inputs from IANA to
improve consistency of the term Next-Header and to add the improve consistency of the term Next-Header and to add the
skipping to change at line 1959 skipping to change at line 2031
(vi) Check for <- -> sequences of characters. (GF) (vi) Check for <- -> sequences of characters. (GF)
(vii) Update refs to add RFC3667 / 3668. (GF) (vii) Update refs to add RFC3667 / 3668. (GF)
(viii) Changed text defining M in DSMCC definition to the word Media (viii) Changed text defining M in DSMCC definition to the word Media
(ix) 7.1.1 Range of PP values corrected to 0-181. (ix) 7.1.1 Range of PP values corrected to 0-181.
(x) Definition of END INDICATOR corrected in section 2 - this is (x) Definition of END INDICATOR corrected in section 2 - this is
not a TYPE value, but a LENGTH value. not a TYPE value, but a LENGTH value.
(xi) Next-Header used throughout the document to replace (xi) Next-Header used throughout the document to replace
next-layer-header, and various other forms of wording. next-layer-header, and various other forms of wording.
(xii) In section 7.2, added a ref the section on PP checking (xii) In section 7.2, added a ref the section on PP checking
Expires July 2005 [page 45]
Working Group ID rev 04 Working Group ID rev 04
This rev followed WGLC comments, which are defined in the ipdvb This rev followed WGLC comments, which are defined in the ipdvb
mailing list. Important changes included: mailing list. Important changes included:
(i) This text was moved to an appendix (i) This text was moved to an appendix
(ii) ToC was updated and section headers made consistent (ii) ToC was updated and section headers made consistent
(iii) Revised definition text (iii) Revised definition text
(iv) Improved clarity with respect to terms defined in ISO 18181-1 (iv) Improved clarity with respect to terms defined in ISO 13818-1
(v) Bridging and Extension-Padding formats move to section 5 (v) Bridging and Extension-Padding formats move to section 5
(vi) Clarification of the NPA in packet headers (vi) Clarification of the NPA in packet headers
(vii) Clarification of placement of NPA address with extension headers. (vii) Clarification of placement of NPA address with extension
headers.
[END of RFC EDITOR NOTE] Issues address in rev-05:
These revisions were made following a second WGLC and invited cross-
area IETF review of the Spec.
NiTS corrected:
Expires July 2005 [page 46] Expires July 2005 [page 46]
Abstract shortened.
Added separate references to Ethernet v2; LLC; and 802.3
Added RFC2119 Boilerplate for definitions of capitilised words.
Corrected English and 63 typos
Specified explicitly that Test & Bridge Extension Headers must be
the last in the extension chain (no other headers may follow)
7.1.1. para 1 - changed PP processing description to specify where
to count the number of bytes that were pointed to
Corrected the range 0-512 in the IANA Guidelines (should be 0-511).
Fixed NPA to consistently refer to the ULE destination address.
Specific Issues:
1) The reviewer suggested the title was confusing. A proposed new
Title is:
Ultra Lightweight Encapsulation (ULE) for transmission of
IP datagrams over an MPEG-2 Transport Stream
2) The reviewer suggested that the name of the D field was changed,
to make the meaning more obvious. The new name is Destination
Address Absent field, rather than the Destination Address
Present field. The semantics of the D-bit do not change.
3) The reviewer asked for a description of how to send an LLC frame
- in Section 4. This was added to the section on bridging.
4) The reviewer mentioned that we had NOT defined the values needed
for mapping addresses... I'm not sure this was an over-sight, but
This was an oversight, the new text was added to the end of the
description in section 4.5. Also added references to [RFC1112]
[RFC2464].
5) Added text on the need for data descriptors.
6) Removed reference to RFC3819 which was either ambiguous in the
definition of SNDU.
7) In final clause of 7.2 (Receiver processing) the last sentence
was extended by a bracketed clause to deal with the case when there
was excess data and no PUSI set).
(iii) If two or more bytes of TS Packet payload data remain after
completion of the Current SNDU, the Receiver accepts the next 2
bytes and examines if this is an End Indicator. When an End
Indicator is received, a Receiver MUST silently discard the
remainder of the TS Packet payload and transition to the Idle State.
Otherwise this is the start of the next Packed SNDU and the Receiver
continues by processing this SNDU (provided that the TS Packet has a
PUSI value of 1, see 7.2.1, otherwise the Receiver has detected a
delimiting error and MUST discard all remaining bytes in the TS
Packet payload and transitions to the Idle State).
Expires July 2005 [page 47]
8) Revised IANA procedures to REQUIRE a definition of the PROCEDURE
when defining an extension header.
[END of RFC EDITOR NOTE]
Expires July 2005 [page 48]
 End of changes. 

This html diff was produced by rfcdiff 1.23, available from http://www.levkowetz.com/ietf/tools/rfcdiff/