draft-ietf-ipdvb-ule-02.txt   draft-ietf-ipdvb-ule-03.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, U.K.
Document: draft-ietf-ipdvb-ule-02.txt Bernhard Collini-Nocker Document: draft-ietf-ipdvb-ule-03.txt Bernhard Collini-Nocker
University of Salzburg, A University of Salzburg, A
ipdvb WG ipdvb WG
Category: Draft, Intended Standards Track October 2004 Category: Draft, Intended Standards Track November 2004
Ultra Lightweight Encapsulation (ULE) for transmission of Ultra Lightweight Encapsulation (ULE) for transmission of
IP datagrams over MPEG-2/DVB networks IP datagrams over MPEG-2/DVB networks
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
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Internet-Drafts are draft documents valid for a maximum of Drafts. Internet-Drafts are draft documents valid for a maximum of
six months and may be updated, replaced, or obsoleted by other six months and may be updated, replaced, or obsoleted by other
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/ietf/1id-abstracts.txt 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 TS has been widely accepted not only for providing
digital TV services, but also as a subnetwork technology for digital TV services, but also as a subnetwork technology for
building IP networks. This document describes an Ultra Lightweight building IP networks. This document describes an Ultra Lightweight
Encapsulation (ULE) mechanism for the transport of IPv4 and IPv6 Encapsulation (ULE) mechanism for the transport of IPv4 and IPv6
Datagrams and other network protocol packets directly over ISO MPEG- Datagrams and other network protocol packets directly over ISO MPEG-
2 Transport Streams (TS) as TS Private Data. ULE supports an 2 Transport Streams (TS) as TS Private Data. ULE supports an
extension format that allows it to carry both optional (with an extension format that allows it to carry both optional (with an
explicit extension length) and mandatory (with an implicit extension explicit extension length) and mandatory (with an implicit extension
length) header information to assist in network/Receiver processing length) header information to assist in network/Receiver processing
of a SNDU. of a SNDU.
Expires April 2005 [page 1]
[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:
ip-dvb@erg.abdn.ac.uk ip-dvb@erg.abdn.ac.uk
skipping to change at line 93 skipping to change at page 3, line 4
* 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.
-------------------------------------------------------------------- --------------------------------------------------------------------
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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 145 skipping to change at page 4, line 5
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 December 2004 [page 3]
* 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 192 skipping to change at page 4, line 51
* Re issue as working group draft (filename change) * Re issue as working group draft (filename change)
* Refinement of the text on CRC generation to be unambiguous. * Refinement of the text on CRC generation to be unambiguous.
* 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 * 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)
Working Group ID rev 01 Working Group ID rev 01
Issues addressed: Issues addressed:
* Typographical * Typographical
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* 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-
RCS compatibility)? Requirement to be clarified! Implementation RCS compatibility)? Requirement to be clarified! Implementation
impact to be evaluated! impact to be evaluated!
Current Recommendation: The current spec does not preclude use of Current Recommendation: The current spec does not preclude use of
AF, it simply says that this is not the standard for ULE. The use AF, it simply says that this is not the standard for ULE. The use
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* Verify the minimum value allocated to DIX Ethernet Header Types. * Verify the minimum value allocated to DIX Ethernet Header Types.
Draft updated to align with IEEE Registry assignments. Draft updated to align with IEEE Registry assignments.
-------------------------------------------------------------------- --------------------------------------------------------------------
Working Group ID rev 02 Working Group ID rev 02
Revised IPR disclosure Revised IPR disclosure
Revised copyright notice Revised copyright notice
Section 5 added to ULE to define optional extension headers (see Section 5 added to ULE to define optional Extension Headers (see
xule) xule)
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.
7.2 Changed, New text: <<SNDUs that contain an invalid CRC value MUST Working Group ID rev 03
be discarded, causing the Receiver to processes the next in-sequence
SNDU (if any).>> The rationale is that the this a SNDU-integrity
check - rather than a framing issue. The mantra of being liberal in
what is accepted suggests we discard, but not that we also discard
succeeding SNDUs.
Known issues with this revision of the document: Changes with this revision of the document:
(i) The worked hexadecimal example in the annexe needs to be (i) The worked hexadecimal example in the annexe was reworked to
reworked. include a valid MAC address for an IPv6 unicast packet. -
(ii) The IANA procedures need to be checked with IANA. (BCN)
(iii) Format page breaks in next rev!
[END of RFC EDITOR NOTE] (ii) The IANA procedures revised, based on inputs from IANA to
improve consistency of the term Next-Header and to add the
HLEN field to the IANA registry record for OPTIONAL headers.
(GF)
Expires December 2004 [page 5] (iii) 7.2 Change to revert wording in the second para to MUST enter
IDLE after CRC failure of SNDU check.
(iv) In normal operation, it is expected that any padding appended
to a bridged Ethernet frame SHOULD be removed prior to
forwarding. This requires the sender to be aware of such
Ethernet padding (e.g. LLC). (Made this a SHOULD). (GF)
NiTS:
(v) Format of page Breaks was updated. (GF)
(vi) Check for <- -> sequences of characters. (GF)
(vii) Update refs to add RFC3667 / 3668. (GF)
(viii) Changed text defining M in DSMCC definition to the word Media
(ix) 7.1.1 Range of PP values corrected to 0-181.
(x) Definition of END INDICATOR corrected in section 2 - this is
not a TYPE value, but a LENGTH value.
(xi) Next-Header used throughout the document to replace
next-layer-header, and various other forms of wording.
(xii) In section 7.2, added a ref the section on PP checking
[END of RFC EDITOR NOTE]
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 Field 4.1 Destination Address Present 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: IANA Assigned 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
4.7.3 IPv6 SNDU Encapsulation 4.7.3 IPv6 SNDU Encapsulation
4.7.4 Test SNDU 4.7.4 Test SNDU
5. Extension Headers 5. Extension Headers
5.1 Mandatory Extension Header 5.1 Mandatory Extension Header
5.2 Optional Extension Header 5.2 Optional Extension Header
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12. Authors' Addresses 12. Authors' Addresses
13. IPR Notices 13. IPR Notices
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
ANNEXE A: Informative Appendix - SNDU Packing Examples ANNEXE A: Informative Appendix - SNDU Packing Examples
ANNEXE B: Informative Appendix - SNDU Encapsulation ANNEXE B: Informative Appendix - SNDU Encapsulation
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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-MPEG; 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
skipping to change at line 327 skipping to change at page 9, line 5
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) by adding an encapsulation header and a Subnetwork Data Unit (SNDU) by adding an encapsulation header and
an integrity check trailer. The SNDU is fragmented into a series of an integrity check trailer. The SNDU is fragmented into a series of
TS Packets) that are sent over a single TS Logical Channel. TS Packets) that are sent over a single TS Logical Channel.
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2. Conventions used in this document 2. Conventions used in this document
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-MPEG].
AFC: Adaptation Field Control, a pair of bits carried in the TS AFC: Adaptation Field Control, a pair of bits carried in the TS
Packet header that signal the presence of the Adaptation Field Packet header that signal the presence of the Adaptation Field
and/or TS Packet payload. 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.
DSM-CC: Digital Storage Management Command and Control [ISO-DSMCC]. DSM-CC: Digital Storage Media Command and Control [ISO-DSMCC]. A
A format for transmission of data and control information defined by format for transmission of data and control information defined by
the ISO MPEG-2 standard that is carried in an MPEG-2 Private the ISO MPEG-2 standard that is carried in an MPEG-2 Private
Section. 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 Type value that indicates to the Receiver that END INDICATOR: A value that indicates to the Receiver that there are
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 MAC: Medium Access and Control. The link layer header of the
Ethernet IEEE 802 standard of protocols, consisting of a 6B Ethernet IEEE 802 standard of protocols, consisting of a 6B
destination address, 6B source address, and 2B type field. destination address, 6B source address, and 2B type field.
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) [ISO-MPEG].
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 B
destination address (similar to an Ethernet MAC address) within the destination address (similar to an Ethernet MAC address) within the
MPEG-2 transmission network used to identify individual Receivers or MPEG-2 transmission network used to identify individual Receivers or
groups of Receivers. groups of Receivers.
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 PDU include Ethernet frames, PDU: Protocol Data Unit. Examples of PDU include Ethernet frames,
IPv4 or IPv6 datagrams, and other network packets IPv4 or IPv6 datagrams, and other network packets
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PES: Packetized Elementary Stream of MPEG-2 [ISO-MPEG]. PES: Packetized Elementary Stream of MPEG-2 [ISO-MPEG].
PID: Packet Identifier. A 13 bit field carried in the header of TS PID: Packet Identifier. A 13 bit field carried in the header of TS
Packets. This is used to identify the TS Logical Channel to which a Packets. This is used to identify the TS Logical Channel to which a
TS Packet belongs [ISO-MPEG]. The TS Packets forming the parts of a TS Packet belongs [ISO-MPEG]. The TS Packets forming the parts of a
Table Section, PES, or other payload unit must all carry the same Table Section, PES, or other payload unit must all carry the same
PID value. The all 1s PID value indicates a Null TS Packet PID value. The all 1s PID value indicates a Null TS Packet
introduced to maintain a constant bit rate of a TS Multiplex. introduced to maintain a constant bit rate of a TS Multiplex.
PP: Payload Pointer. An optional one byte pointer that directly PP: Payload Pointer. An optional one byte pointer that directly
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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 as illustrated in the TS HEADER: The 4 byte header of a TS Packet as illustrated in the
introduction. introduction.
TS LOGICAL CHANNEL: Transport Stream Logical Channel, a channel TS LOGICAL CHANNEL: Transport Stream Logical Channel, a channel
identified at the MPEG-2 level [ISO-MPEG]. It exists at level 2 of identified at the MPEG-2 level [ISO-MPEG]. It exists at level 2 of
the ISO/OSI reference model. All packets sent over a TS Logical the ISO/OSI reference model. All packets sent over a TS Logical
Channel carry the same PID value. According to MPEG-2, some TS Channel carry the same PID value. According to MPEG-2, some TS
Logical Channels are reserved for specific signalling purposes. Logical Channels are reserved for specific signalling purposes.
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Other standards (e.g., ATSC, DVB) also reserve specific TS Logical Other standards (e.g., ATSC, DVB) also reserve specific TS Logical
Channels. Channels.
TS MULTIPLEX: A set of MPEG-2 TS Logical Channels sent over a single TS MULTIPLEX: A set of MPEG-2 TS Logical Channels sent over a single
common physical link (i.e. a transmission at a specified symbol common physical link (i.e. a transmission at a specified symbol
rate, FEC setting, and transmission frequency). The same TS Logical rate, FEC setting, and transmission frequency). The same TS Logical
Channel may be repeated over more than one TS Multiplex, for example Channel may be repeated over more than one TS Multiplex, for example
to redistribute the same multicast content to two terrestrial TV to redistribute the same multicast content to two terrestrial TV
transmission cells. transmission cells.
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8b Synchronisation pattern equal 0x47 8b Synchronisation pattern equal 0x47
*1b Transport Error Indicator *1b Transport Error Indicator
*1b Payload Unit Start Indicator (PUSI) *1b Payload Unit Start Indicator (PUSI)
1b Transport Priority 1b Transport Priority
*13b Packet IDentifier (PID) *13b Packet IDentifier (PID)
2b Transport scrambling control 2b Transport scrambling control
*2b Adaptation Field Control (AFC) *2b Adaptation Field Control (AFC)
*4b Continuity Counter (CC) *4b Continuity Counter (CC)
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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 a SNDU MUST be assigned
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The TS Packet Header also carries a two bit Adaptation Field Control The TS Packet Header also carries a two bit Adaptation Field Control
(AFC) value. The purpose of the adaptation field is primarily to (AFC) value. The purpose of the adaptation field is primarily to
extend the TS header for timing and synchronisation information and extend the TS header for timing and synchronisation information and
may be used to also include stuffing bytes before a TS Packet may be used to also include stuffing bytes before a TS Packet
payload. Standard Receivers discard TS Packets with an payload. Standard Receivers discard TS Packets with an
adaptation_field_control field value of '00'. Adaptation Field adaptation_field_control field value of '00'. Adaptation Field
stuffing is NOT used in this encapsulation method, and TS Packets stuffing is NOT used in this encapsulation method, and TS Packets
from a ULE Encapsulator MUST be sent with an AFC value of '01'. from a ULE Encapsulator MUST be sent with an AFC value of '01'.
Receivers MUST discard TS Packets that carry other AFC values. Receivers MUST discard TS Packets that carry other AFC values.
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4. SNDU Format 4. SNDU Format
PDUs (IP packets and bridged Ethernet frames) are encapsulated using PDUs (IP packets and bridged Ethernet frames) are encapsulated using
ULE to form a SNDU. Each SNDU is sent as an MPEG-2 Payload Unit. The ULE to form a SNDU. Each SNDU is sent as an MPEG-2 Payload Unit. The
encapsulation format to be used for PDUs is illustrated below: encapsulation format to be used for PDUs is illustrated below:
< ----------------------------- SNDU ----------------------------- > < ----------------------------- SNDU ----------------------------- >
+-+-------------------------------------------------------+--------+ +-+-------------------------------------------------------+--------+
|D| Length | Type | PDU | CRC-32 | |D| Length | Type | PDU | CRC-32 |
+-+-------------------------------------------------------+--------+ +-+-------------------------------------------------------+--------+
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present (i.e. it is omitted). present (i.e. it is omitted).
By default, the D-bit value MUST be set to a value of 0, except for By default, the D-bit value MUST be set to a value of 0, except for
the transmission of an End Indicator (see 4.3), in which this bit the transmission of an End Indicator (see 4.3), in which this bit
MUST be set to the value of 1. 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 (encapsulated Ethernet frame, IP datagram or other packet) counted
from the byte following the type field up to and including the CRC. from the byte following the Type field, up to and including 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 a 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). It indicates to the Receiver that there are no further value of 1). It indicates to the Receiver that there are no further
SNDUs present within the current TS Packet (see section 6), and that SNDUs present within the current TS Packet (see section 6), and that
no Destination Address Field is present. The value 0xFF has specific no Destination Address Field is present. The value 0xFF has specific
semantics in MPEG-2 framing, where it is used to indicate the semantics in MPEG-2 framing, where it is used to indicate the
presence of Padding. This use resembles [ISO-DSMCC]. presence of Padding. This use resembles [ISO-DSMCC].
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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 a
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 DIX
framework for Ethernet. After specification of IEEE 802.3 [LLC], the framework for Ethernet. After specification of IEEE 802.3 [LLC], the
set of Ethertypes less than 1536 (0x0600), assumed the role of a set of EtherTypes less than 1536 (0x0600), assumed the role of a
length indicator. Ethernet receivers use this feature to length indicator. Ethernet receivers use this feature to
discriminate LLC format frames. Hence any IEEE Ethertype < 1536 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
consideration (section 4.7.5). consideration (section 4.7.5).
The Ethernet LLC mode of identification is not required in ULE, The Ethernet LLC mode of identification is not required in ULE,
since the SNDU format always carries an explicit Length Field, and since the SNDU format always carries an explicit Length Field, and
therefore the procedure in ULE is modified, as below: therefore the procedure in ULE is modified, as below:
The first set of ULE Type Field values comprise the set of values < The first set of ULE Type field values comprise the set of values <
1536. These Type Field values are IANA assigned (see 4.4.1), and 1536. These Type field values are IANA assigned (see 4.4.1), and
indicate the Next-Header. indicate the Next-Header.
The second set of ULE Type Field values comprise the set of values The second set of ULE Type field values comprise the set of values
>= 1536. In ULE, this indicates that the value is identical to the >= 1536. In ULE, this indicates that the value is identical to the
corresponding type codes specified by the IEEE/DIX type assignments corresponding type codes specified by the IEEE/DIX type assignments
for Ethernet and recorded in the IANA EtherType registry. for Ethernet and recorded in the IANA EtherType registry.
4.4.1 Type 1: Next-Layer-Header 4.4.1 Type 1: Next-Header Type Fields
The first part of the Type space corresponds to the values 0 to The first part of the Type space corresponds to the values 0 to 1535
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: The following types are defined in this document:
[XXX IANA ACTION REQUIRED XXX] [XXX IANA ACTION REQUIRED XXX]
0x0000: Test SNDU, discarded by the Receiver. 0x0000: Test SNDU, discarded by the Receiver.
0x0001: Bridged Ethernet Frame (i.e. MAC source address follows) 0x0001: Bridged Ethernet Frame (i.e. MAC source address follows)
0x0100: Padding, ignored by the Receiver. 0x0100: Padding, ignored by the Receiver.
[XXX END OF IANA ACTION REQUIRED XXX] [XXX END OF IANA ACTION REQUIRED XXX]
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 allocation by the IANA. reserved for Next-Header values allocated by the IANA.
Expires December 2004 [page 13] 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 1536 The second part of the Type space corresponds to the values 1536
Decimal (0x600) and 0xFFFF. This set of type assignments follow Decimal (0x600) and 0xFFFF. This set of type assignments follow
DIX/IEEE assignments (but exclude use of this field as a frame DIX/IEEE assignments (but exclude use of this field as a frame
length indicator) [LLC]. All assignments in this space MUST use the length indicator) [LLC]. All assignments in this space MUST use the
values defined for IANA EtherType, the following two Type values are values defined for IANA EtherType, the following two Type values are
used as examples (taken from the IANA Ethertypes registry): used as examples (taken from the IANA EtherTypes registry):
0x0800 : IPv4 Payload 0x0800 : IPv4 Payload
0x86DD : IPv6 Payload 0x86DD : IPv6 Payload
4.5 SNDU Destination Address Field 4.5 SNDU Destination Address Field
The SNDU Destination Address Field is optional (see section 4.1). The SNDU Destination Address Field is optional (see section 4.1).
This field MUST be carried (i.e. D=0) for IP unicast packets This field MUST be carried (i.e. D=0) for IP unicast packets
destined to routers that are sent using shared links (i.e., where destined to routers that are sent using shared links (i.e., where
the same link connects multiple Receivers). A sender MAY omit this the same link connects multiple Receivers). A sender MAY omit this
skipping to change at line 679 skipping to change at page 16, line 5
directly follows the SNDU Type Field. NPA destination addresses are directly follows the SNDU Type Field. NPA destination addresses are
6 Byte numbers, normally expressed in hexadecimal, used to identify 6 Byte numbers, normally expressed in hexadecimal, used to identify
the Receiver(s) in a MPEG-2 transmission network that should process the Receiver(s) in a MPEG-2 transmission network that should process
a received SNDU. The value 0x00:00:00:00:00:00, MUST NOT be used as a received SNDU. The value 0x00:00:00:00:00:00, MUST NOT be used as
a destination address in a SNDU. The least significant bit of the a destination address in a SNDU. The least significant bit of the
first byte of the address is set to 1 for multicast frames, and the first byte of the address is set to 1 for multicast frames, and the
remaining bytes specify the link layer multicast address. The remaining bytes specify the link layer multicast address. The
specific value 0xFF:FF:FF:FF:FF:FF is the link broadcast address, specific value 0xFF:FF:FF:FF:FF:FF is the link broadcast address,
indicating this SNDU is to be delivered to all Receivers. indicating this SNDU is to be delivered to all Receivers.
Expires December 2004 [page 14]
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 0x04C11DB7 in hexadecimal: generator polynomial represented 0x104C11DB7 in hexadecimal:
x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x^1+x^0. x^32+x^26+x^23+x^22+x^16+x^12+x^11+x^10+x^8+x^7+x^5+x^4+x^2+x^1+x^0.
The Encapsulator initialises the CRC-32 accumulator register to the The Encapsulator initialises the CRC-32 accumulator register to the
value 0xFFFF FFFF. It then accumulates a transmit value for the value 0xFFFF FFFF. It then accumulates a transmit value for the
CRC32 that includes all bytes from the start of the SNDU header to CRC32 that includes all bytes from the start of the SNDU header to
the end of the SNDU (excluding the 32-bit trailer holding the CRC- the end of the SNDU (excluding the 32-bit trailer holding the CRC-
32), and places this in the CRC Field. In ULE, the bytes are 32), and places this in the CRC Field. In ULE, the bytes are
processed in order of increasing position within the SNDU, the order processed in order of increasing position within the SNDU, the order
of processing bits is NOT reversed. This use resembles, but is of processing bits is NOT reversed. This use resembles, but is
skipping to change at line 720 skipping to change at page 16, line 45
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 December 2004 [page 15]
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 a SNDU is determined by the combination of the
Destination Address Present bit (D) and the SNDU Type Field. The Destination Address Present 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 a 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 directly preceding the PDU. These are inserted in the SNDU directly preceding the PDU.
The following SNDU Formats are defined here: The following SNDU Formats are defined here:
skipping to change at line 755 skipping to change at page 18, line 21
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
|1| 0x7FFF | |1| 0x7FFF |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= Arbitrary number (>= 0) bytes with value 0xFF = = Arbitrary number (>= 0) bytes with value 0xFF =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 2: SNDU Format for an End Indicator. Figure 2: SNDU Format for an End Indicator.
Expires December 2004 [page 16]
4.7.2 IPv4 SNDU 4.7.2 IPv4 SNDU
IPv4 datagrams are transported using one of the two standard SNDU IPv4 datagrams are transported using one of the two standard SNDU
structures, in which the PDU is placed directly in the SNDU payload. structures, in which the PDU is placed directly in the SNDU payload.
The two encapsulations are shown in figures 3 and 4. (Note that in The two encapsulations are shown in figures 3 and 4. (Note that in
this, and the following figures, the IP datagram payload is of this, and the following figures, the IP datagram payload is of
variable size, and is directly followed by the CRC-32). variable size, and is directly followed by the CRC-32).
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
skipping to change at line 796 skipping to change at page 19, line 19
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= 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).
Expires December 2004 [page 17]
4.7.3 IPv6 SNDU Encapsulation 4.7.3 IPv6 SNDU Encapsulation
IPv6 datagrams are transported using one of the two standard SNDU IPv6 datagrams are transported using one of the two standard SNDU
structures, in which the PDU is placed directly in the SNDU payload. structures, in which the PDU is placed directly in the SNDU payload.
The two encapsulations are shown in figures 5 and 6. The two encapsulations are shown in figures 5 and 6.
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 = 0x086DD |
skipping to change at line 835 skipping to change at page 20, line 5
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= 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 December 2004 [page 18]
4.7.4 Test SNDU 4.7.4 Test SNDU
A Test SNDU is of Type 1 (figure 7). The structure of the Data A Test SNDU is of Type 1 (figure 7). 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at line 886 skipping to change at page 21, line 4
| | EtherType (2B) | | | EtherType (2B) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| | | |
= (Contents of bridged MAC frame) = = (Contents of bridged MAC frame) =
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (CRC-32) | | (CRC-32) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 8: SNDU Format for a Bridged Payload (D=0) Figure 8: SNDU Format for a Bridged Payload (D=0)
Expires December 2004 [page 19]
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) |
skipping to change at line 917 skipping to change at page 21, line 33
Figure 9: SNDU Format for a Bridged Payload (D=1) Figure 9: SNDU Format for a Bridged Payload (D=1)
Note: The final two bytes of the bridging header also carry a Type Note: The final two bytes of the bridging header also carry a Type
field (see section 5). In this special case, the extension mandatory field (see section 5). In this special case, the extension mandatory
header format permits this to carry a LLC Length field, specified by header format permits this to carry a LLC Length field, specified by
IEEE 802 [LLC] rather than an IANA assigned value. IEEE 802 [LLC] rather than an IANA assigned value.
When an NPA address is specified (D=0), Receivers MUST discard all When an NPA address is specified (D=0), Receivers MUST discard all
SNDUs that carry an NPA address that does NOT match their own NPA SNDUs that carry an NPA address that does NOT match their own NPA
address (or a broadcast/mcast address), the payload of the remaining address (or a broadcast/multicast address), the payload of the
SNDUs are processed by the bridging rules that follow. An SNDU remaining SNDUs are processed by the bridging rules that follow. An
without an NPA address (D=1) results in a Receiver performing SNDU without an NPA address (D=1) results in a Receiver performing
bridging processing on the payload of all received SNDUs. bridging processing on the payload of all 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. The EtherType field of a frame is defined according
to Ethernet/LLC [LLC]. 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 will 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. the sender to be aware of such Ethernet padding (e.g. LLC).
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). The Encapsulator MUST check the
LAN-FCS value of all frames received, prior to further processing. LAN-FCS value of all frames received, prior to further processing.
Frames received with an invalid LAN FCS MUST be discarded. After Frames received with an invalid LAN FCS MUST be discarded. After
checking, the LAN FCS is then removed (i.e., it is NOT forwarded in checking, the LAN FCS is then removed (i.e., it is NOT forwarded in
the bridged SNDU). As in other ULE frames, the Encapsulator appends the bridged SNDU). As in other ULE frames, the Encapsulator appends
a CRC-32 to the transmitted SNDU. At the Receiver, an appropriate a CRC-32 to the transmitted SNDU. At the Receiver, an appropriate
LAN-FCS field will be appended to the bridged frame prior to onward LAN-FCS field will be appended to the bridged frame prior to onward
transmission on the Ethernet interface. transmission on the Ethernet interface.
Expires December 2004 [page 20]
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).
Expires December 2004 [page 21]
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 a next-layer-header and is assigned from a separate IANA indicates an Extension Header. These values are assigned from a
registry defined for ULE. separate IANA registry defined for ULE.
The use of a single Type/next-layer-header registry simplifies The use of a single Type/Next-Header field simplifies processing and
processing and eliminates the need to maintain multiple IANA eliminates the need to maintain multiple IANA registries. The cost
registries. The cost is that each extension header requires at least is that each Extension Header requires at least 2 bytes. This is
2 bytes. This is justified, on the basis of simplified processing justified, on the basis of simplified processing and maintaining a
and maintaining a simple lightweight header for the common case when simple lightweight header for the common case when no extensions are
no extensions are present. present.
The 16-bit ULE next-layer-header field is used in place of the Type A ULE Extension Header is identified by a 16-bit value in the Type
value. It is organised as a 5-bit zero prefix, a 3-bit H-LEN field field. It is organised as a 5-bit zero prefix, a 3-bit H-LEN field
and an 8-bit H-Type field, as follows: and an 8-bit H-Type field, as follows:
+----+-----+--------+ +----+-----+--------+
|0000|H-LEN| H-TYPE | |0000|H-LEN| H-TYPE |
+----+-----+--------+ +----+-----+--------+
Figure 10: Structure of ULE Next-Layer-Header Extension Type. Figure 10: Structure of ULE Next-Header Field.
The H-LEN Assignment The H-LEN Assignment is described below:
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 10BX 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.
A H-LEN of zero indicates a Mandatory Extension Header. Each A H-LEN of zero indicates a Mandatory Extension Header. Each
specific Mandatory Extension header has a pre-defined length, that Mandatory Extension Header has a pre-defined length that is not
is not communicated in the H-LEN field. No additional limit is communicated in the H-LEN field. No additional limit is placed on
placed on the maximum length of a Mandatory Extension Header. A the maximum length of a Mandatory Extension Header. A Mandatory
Mandatory Extension header MAY modify the format or encoding of the Extension Header MAY modify the format or encoding of the enclosed
enclosed PDU (e.g. to perform encryption and/or compression). PDU (e.g. to perform encryption and/or compression).
The H-Type is sent in a one byte field which may be either be The H-Type is a one byte field that may be either one of 256
one of 256 Mandatory Header Extensions or one of 256 Optional Mandatory Header Extensions or one of 256 Optional Header
Header Extensions. The set of currently permitted H-Type values Extensions. The set of currently permitted values for both types of
for both types of header extension are defined by an IANA Registry. Extension Headers are defined by an IANA Registry (section 15).
Registry values for Optional Extensions are specified in the form
H=1 (i.e. a decimal number in the range 256-511), but may be used
with an H-Length value in the range 1-5.
The simplest examples of Extension Headers are Test and Padding. Two examples of Extension Headers are the Test_SNDU and the use of
The Test Mandatory Extension Header results in the entire PDU Extension-Padding. The Test-SNDU Mandatory Extension Header results
being discarded. The Padding Optional Extension Header results in the entire PDU being discarded. The Extension-Padding Optional
in the following (if any) option header being ignored. Extension Header results in the following (if any) option header
being ignored (i.e. a total of H-LEN 16-bit words).
Expires December 2004 [page 22] The general format for an SNDU with Extension Headers is:
The general format for an SNDU with extension headers is:
<-------------------------- SNDU ---------------------------> < -------------------------- SNDU ------------------------- >
+---+--------------------------------------------------+--------+ +---+--------------------------------------------------+--------+
|D=1| Length | T1 | H1 | T2 | PDU | CRC-32 | |D=1| Length | T1 | H1 | T2 | PDU | CRC-32 |
+---+--------------------------------------------------+--------+ +---+--------------------------------------------------+--------+
<-ULE base header->< ext 1 > < ULE base header >< ext 1 >
Figure 11: SNDU Encapsulation with one Extension Header Figure 11: SNDU Encapsulation with one Extension Header
Where: Where:
D is the ULE D_bit (in this example D=1, however NPA addresses may D is the ULE D_bit (in this example D=1, however NPA addresses may
also be used in combination with extension headers). also be used in combination with Extension Headers).
T1 is the base header Type field. In this case, specifying a T1 is the base header Type field. In this case, specifying a
next-layer-header value. Next-Header value.
H1 is a set of fields defined for header type T1. There may be 0 H1 is a set of fields defined for header type T1. There may be 0
or more bytes of information for a specific ULE extension header. or more bytes of information for a specific ULE Extension Header.
T2 is the Type field of the next header, i.e. a value > 1535 B T2 is the Type field of the next header, or an EtherType > 1535 B
indicating the Ethertype of the PDU being carried. indicating the type of the PDU being carried.
<-------------------------- SNDU ---------------------------> < -------------------------- SNDU ------------------------- >
+---+---------------------------------------------------+--------+ +---+---------------------------------------------------+--------+
|D=1| Length | T1 | H1 | T2 | H2 | T3 | PDU | CRC-32 | |D=1| Length | T1 | H1 | T2 | H2 | T3 | PDU | CRC-32 |
+---+---------------------------------------------------+--------+ +---+---------------------------------------------------+--------+
<ULE base header-> < ext 1 > < ext 2 > < ULE base header >< ext 1 >< ext 2 >
Figure 12: SNDU Encapsulation with two Extension Headers Figure 12: SNDU Encapsulation with two Extension Headers
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. series. Figure 12 shows an SNDU including two Extension Headers. The
The values of T1 and T2 are both less than 1536 Decimal, each values of T1 and T2 are both less than 1536 Decimal, each indicates
indicating the presence of a next-layer-header rather than a the presence of an Extension Header rather than a directly following
directly following PDU. T3 has a value > 1535 indicating the PDU. T3 has a value > 1535 indicating the EtherType of the PDU being
Ethertype of the PDU being carried. Although an SNDU may contain carried. Although an SNDU may contain an arbitrary number of
an arbitrary number of consecutive extension headers, it is not consecutive Extension Headers, it is not expected that SNDUs will
expected that SNDUs will generally carry a large number. generally carry a large number of extensions.
Expires December 2004 [page 23]
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. (re)multiplexors before it is finally delivered to a Receiver.
skipping to change at line 1099 skipping to change at page 26, line 5
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). It informs the Receiver
that there are no more SNDUs in this TS Packet payload. The End that there are no more SNDUs in this TS Packet payload. The End
Indicator is followed by zero or more unused bytes until the end of Indicator is followed by zero or more unused bytes until the end of
the TS Packet payload. All unused bytes MUST be set to the value of the TS Packet payload. All unused bytes MUST be set to the value of
0xFF, following current practice in MPEG-2 [ISO-DSMCC]. The padding 0xFF, following current practice in MPEG-2 [ISO-DSMCC]. The padding
procedure trades decreased efficiency against improved latency. procedure trades decreased efficiency against improved latency.
Expires December 2004 [page 24]
+-/------------+ +-/------------+
| 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 1148 skipping to change at page 26, line 53
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 require the header of this new a new TS Packet. (The standard rules [ISO-MPEG] require the header
TS Packet to carry a PUSI value of 1, and a Payload Pointer value of of this new TS Packet to carry a PUSI value of 1, and a Payload
0x00.) Pointer value of 0x00.)
(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 a SNDU has one byte
of unused payload, the Encapsulator MUST place the value 0xFF in of unused payload, the Encapsulator MUST place the value 0xFF in
this final byte, and transmit the TS Packet. This rule provides a 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
Expires December 2004 [page 25]
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 a SNDU has exactly
two bytes of unused payload, and the PUSI was NOT already set, the two bytes of unused payload, and the PUSI was NOT already set, the
Encapsulator MUST place the value 0xFFFF in this final two bytes, Encapsulator MUST place the value 0xFFFF in this final two bytes,
skipping to change at line 1182 skipping to change at page 27, line 32
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 require the header of this new TS Packet to carry a standard rules [ISO-MPEG] require the header of this new TS Packet
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 payload 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
skipping to change at line 1219 skipping to change at page 29, line 14
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
Expires December 2004 [page 26]
reassembly, the Receiver may use a buffer to hold the partially reassembly, the Receiver may use a buffer to hold the partially
assembled SNDU, referred to here as the Current SNDU buffer. Other assembled SNDU, referred to here as the Current SNDU buffer. Other
implementations may choose to use other data structures, but MUST implementations may choose to use other data structures, but MUST
provide equivalent operations. provide equivalent operations.
Receipt of a TS Packet with a PUSI value of 1 indicates that the TS Receipt of a TS Packet with a PUSI value of 1 indicates that the TS
Packet contains the start of a new SNDU. It also indicates the Packet contains the start of a new SNDU. It also indicates the
presence of the Payload Pointer (indicating the number of bytes to presence of the Payload Pointer (indicating the number of bytes to
the start of the first SNDU in the TS-Packet currently being the start of the first SNDU in the TS-Packet currently being
reassembled). It is illegal to receive a Payload Pointer value reassembled). It is illegal to receive a Payload Pointer value
skipping to change at line 1247 skipping to change at page 29, line 40
with or without a Destination Address Field (i.e. D=0 and D=1). with or without a Destination Address Field (i.e. D=0 and D=1).
7.1 Idle State 7.1 Idle State
After initialisation, errors, or on receipt of an End Indicator, the After initialisation, errors, or on receipt of an End Indicator, the
Receiver enters the Idle State. In this state, the Receiver discards Receiver enters the Idle State. In this state, the Receiver discards
all TS Packets until it discovers the start of a new SNDU, when it all TS Packets until it discovers the start of a new SNDU, when it
then enters the Reassembly State. Figure 16 outlines these state then enters the Reassembly State. Figure 16 outlines these state
transitions: transitions:
Expires December 2004 [page 27]
+-------+ +-------+
| START | | START |
+---+---+ +---+---+
| |
\/ \/
+----------+ +----------+
\| Idle |/ \| Idle |/
+-------/| State |\-------+ +-------/| State |\-------+
Insufficient | +----+-----+ | Insufficient | +----+-----+ |
unused space | | PUSI set | MPEG-2 TS Error unused space | | PUSI set | MPEG-2 TS Error
skipping to change at line 1265 skipping to change at page 30, line 4
+-------/| State |\-------+ +-------/| State |\-------+
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
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 1 and 182 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 from
the start of the TS Packet payload, before leaving the Idle State. the start of the TS Packet payload, before leaving the Idle State.
It then enters the Reassembly State, and starts reassembly of a new 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. When Current SNDU length equals the value of TS Packet is reached (see also 7.2.1). When Current SNDU length
the Length Field, the Receiver MUST calculate and verify the CRC equals the value of the Length Field, the Receiver MUST calculate
value (section 4.6). SNDUs that contain an invalid CRC value MUST be and verify the CRC value (section 4.6). SNDUs that contain an
discarded, causing the Receiver to processes the next in-sequence invalid CRC value MUST be discarded. Mismatch of the CRC is an error
SNDU (if any). event and SHOULD be recorded as a CRC error. The under-lying
physical-layer processing (e.g. forward error correction coding)
often results in patterns of errors, rather than since bit errors,
so the Receiver needs to be robust to arbitrary patterns of
corruption to the TS Packet and payload, including potential
corruption of the PUSI, PP, and SNDU Length fields. Therefore, a
Receiver SHOULD discard the remaining TS Packet payload (if any)
following a CRC musmatch 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 extensions specified). The SNDU payload is (and process any Type 1 Extension Headers). The SNDU payload is then
then passed to the next protocol layer specified. An SNDU with an passed to the next protocol layer specified. An SNDU with an unknown
unknown Type value < 1536 MUST be discarded. This error event SHOULD Type value < 1536 MUST be discarded. This error event SHOULD be
be recorded as a SNDU type error. recorded as a SNDU type error.
Expires December 2004 [page 28]
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.
(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
skipping to change at line 1344 skipping to change at page 31, line 37
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.
Expires December 2004 [page 29]
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. This flag indicates a transmission carried in the TS Packet header [ISO-MPEG]. This flag indicates a
error for a TS Logical Channel. If the flag is set to a value of transmission error for a TS Logical Channel. If the flag is set to a
one, a transmission error event SHOULD be recorded. Any partially value of one, a transmission error event SHOULD be recorded. Any
received SNDU MUST be discarded. The Receiver then enters the Idle partially received SNDU MUST be discarded. The Receiver then enters
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-MPEG]. 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
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.
skipping to change at line 1382 skipping to change at page 33, line 13
protocol. protocol.
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 capability with
existing implementations. In particular, Optional Extension Headers existing implementations. In particular, Optional Extension Headers
may safely be ignored by drivers that do not implement them, or may safely be ignored by drivers that do not implement them, or
choose not to process them. choose not to process them.
Expires December 2004 [page 30]
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 Patrick Cipiere, Wolgang Fritsche, Hilmar
Linder, Alain Ritoux, and William Stanislaus. Alain also provided Linder, Alain Ritoux, and William Stanislaus. Alain also provided
the original examples of usage. the original examples of usage.
skipping to change at line 1433 skipping to change at page 34, line 37
length error SHOULD be recorded. length error SHOULD be recorded.
ULE supports optional link level encryption of the SNDU payload. ULE supports optional link level encryption of the SNDU payload.
This is as an additional security mechanism to IP, transport or This is as an additional security mechanism to IP, transport or
application layer security - not a replacement [ID-ipdvb-arch]. The application layer security - not a replacement [ID-ipdvb-arch]. The
approach is generic and decouples the encapsulation from future approach is generic and decouples the encapsulation from future
security extensions. The operation provides functions that resemble security extensions. The operation provides functions that resemble
those currently used with the MPE encapsulation. those currently used with the MPE encapsulation.
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
mechanism to perform link encryption . Additional security control method to perform link encryption. Additional security control
fields may be provided as a part of the extension header, e.g. to fields may be provided as a part of the Extension Header, e.g. to
associate an SNDU with one of a set of Security Association (SA) associate an SNDU with one of a set of Security Association (SA)
parameters. As a part of the encryption process, it may also be parameters. As a part of the encryption process, it may also be
desirable to authenticate some/all of the SNDU headers. The method desirable to authenticate some/all of the SNDU headers. The method
of encryption and the way in which keys are exchanged is beyond the of encryption and the way in which keys are exchanged is beyond the
scope of this specification, as also are the definition of the SA scope of this specification, as also are the definition of the SA
format and that of the related encryption keys. format and that of the related encryption keys.
Expires December 2004 [page 31]
11. References 11. References
11.1 Normative References 11.1 Normative References
[ISO-MPEG] ISO/IEC DIS 13818-1 "Information technology -- Generic [ISO-MPEG] ISO/IEC DIS 13818-1 "Information technology -- Generic
coding of moving pictures and associated audio information: coding of moving pictures and associated audio information:
Systems", International Standards Organisation (ISO). Systems", International Standards Organisation (ISO).
[RFC2026] Bradner, S., "The Internet Standards Process - Revision [RFC2026] Bradner, S., "The Internet Standards Process - Revision
3", BCP 9, RFC 2026, BCP 9, 1996. 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
3667, February 2004.
[RFC3668] Bradner, S., "Intellectual Property Rights in IETF
Technology", BCP 79, RFC 3668, February 2004.
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, 1995. Systems Committee (ATSC), Doc. A/53, 1995.
[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.
skipping to change at line 1501 skipping to change at page 36, line 18
[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
Expires December 2004 [page 32]
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).
[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 is a full software implementation", 6: Extensions for DSM-CC", International Standards Organisation
International Standards Organisation (ISO). (ISO).
[ITU-I363] ITU-T I.363.5 B-ISDN ATM Adaptation Layer Specification [ITU-I363] ITU-T I.363.5 B-ISDN ATM Adaptation Layer Specification
Type AAL5, International Standards Organisation (ISO), 1996. Type AAL5, International Standards Organisation (ISO), 1996.
[LLC] "IEEE Logical Link Control" (ANSI/IEEE Std 802.2/ ISO 8802.2), [LLC] "IEEE Logical Link Control" (ANSI/IEEE Std 802.2/ ISO 8802.2),
1985. 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.
skipping to change at line 1545 skipping to change at page 37, line 21
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.cosy.sbg.ac.at/sc/ Web: http://www.scicomp.sbg.ac.at/
Expires December 2004 [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 1592 skipping to change at page 39, line 5
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 December 2004 [page 34]
15. IANA Considerations 15. IANA Considerations
This document will require IANA involvement. This document will require IANA involvement.
The ULE type field defined in this document requires a registry. The The ULE Next-Header type field defined in this document requires a
payload type field defined in this document requires creation of a registry:
new IANA registry:
ULE Next-Protocol-Header registry ULE Next-Header registry
This registry allocates values 0-512 (decimal). This registry allocates values 0-512 (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-Protocol-Header registry. This registry allocates values Next-Header registry. This registry allocates values decimal 0-512
decimal 0-512 (0x0000-0x01FF, hexadecimal). It MUST NOT allocate (0x0000-0x01FF, hexadecimal). It MUST NOT allocate values greater
values greater than 0x01FF (decimal). than 0x01FF (decimal).
It subdivides the Next-Layer-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 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
with the Extension Header. It must also define the need for the
extension and the intended use. The size of the Extension Header
must also be specified.
Assignments made in this document: Assignments made in this document:
0: Test-SNDU Type Name Reference
1: Bridged-SNDU
0: Test-SNDU Section 4.7.4.
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 prior issue of an IETF RFC. Extension Headers for ULE, requiring expert review leading to
prior issue of an IETF RFC. This specification must define the
value, and the name associated with the Extension Header. The
entry must specify range of allowable H-LEN values that are
permitted (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:
256: Padding Type Name H-LEN Reference
256: Extension-Padding 1-5 Section 5.
Expires December 2004 [page 35]
ANNEXE A: Informative Appendix ANNEXE A: Informative Appendix
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-MPEG]. The specification of ULE is provided in
the body of this document. the body of this document.
skipping to change at line 1678 skipping to change at page 41, line 4
+-----+----*-+------+- -+------+-*----+------+- -+------+ +-----+----*-+------+- -+------+-*----+------+- -+------+
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 December 2004 [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 1715 skipping to change at page 42, line 4
+-----+------+------+------+- -+------+------+------+ +-----+------+------+------+- -+------+------+------+
| 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 December 2004 [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 1761 skipping to change at page 43, line 4
| HDR | B002 | ... | B185 | | HDR | B002 | ... | B185 |
+-----+------+- -+------+ +-----+------+- -+------+
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 December 2004 [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
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+ -+------+------+------+ -+------+------+------+- -+------+ + -+------+------+------+ -+------+------+------+- -+------+
+ ... | 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 December 2004 [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 destination MAC address)
SNDU B is 52 bytes (no destination MAC address) SNDU B is 52 bytes (no destination MAC address)
SNDU C is 52 bytes (no destination MAC address) SNDU C is 52 bytes (no destination MAC address)
The sequence comprises 1 TS Packet: The sequence comprises 1 TS Packet:
SNDU SNDU
PP=0 Length PP=0 Length
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| 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 December 2004 [page 40]
ANNEXE B: Informative Appendix - SNDU Encapsulation ANNEXE 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 Present)
ULE Protocol Type : 0x86dd (IPv6) ULE Protocol Type : 0x86dd (IPv6)
Destination ULE NPA Address: 01:02:03:04:05:06 Destination ULE NPA Address: 00:01:02:03:04:05
ULE CRC32 : 0x784679a5 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 01 02 03 04 05 06 60 00 00 00 00 0d 0000: 00 3f 86 dd 00 01 02 03 04 05 60 00 00 00 00 0d
0010: 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
0020: 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
0030: 00 06 80 00 9d 8c 06 38 00 04 00 00 00 00 00 78 0048: 00 06 80 00 9d 8c 06 38 00 04 00 00 00 00 00 47
0040: 46 79 a5 0064: 09 a7 44
>>>> Author Note : This packet is not a valid IPv6 packet since it
has a unicast L3 IP address and a multicast L2 MAC address. A new
packet decode is required. <<<
Expires December 2004 [page 41]
Expires December 2004 [page 42]
 End of changes. 

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