Internet Engineering Task Force Gorry Fairhurst
Internet Draft University of Aberdeen
Document: draft-fair-ipdvb-ar-03.txt Marie-Jose Montpetit
June 2005 Motorola
Hidetaka Izumiyama
Wishnet
Category: Informational Expires June 2005
Address Resolution for IP datagrams over MPEG-2 networks
Status of this Memo
By submitting this Internet-Draft, each author represents that any
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Copyright (C) The Internet Society (2005). This document is subject
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Abstract
This document describes the current mechanisms to bind IPv4/IPv6
addresses and flows to MPEG-2 Transport Streams (TS)and how these
methods interact with well known protocols for address management
like DHCP, ARP, NAT and DNS. For MPEG-2 subnetworks like any
other IP networks methods are required to signal IPv4/v6
addresses to the link receivers and transmitters; this is known
as Address Resolution (AR), or Neighbour Discovery (ND). Although
AR is often associated with Ethernet [RFC803], it is essential
to the operation of any L2 network. In MPEG-2 networks, an IP
address must be associated with a Packet ID (PID) and specific
transmission multiplex either statically or via the use of some
specific tables. Address resolution complements the higher
layer resource discovery tools that are used to advertise
IP sessions. In this document the different mechanisms for
address resolution for MPEG-2 networking as well as their usage
are reviewed.
Table of Contents
1. Introduction
2. Convention used in the document
3. Address Resolution Requirement
4. MPEG-2 Address Resolution
5. Mapping IP addresses to NPA/MAC addresses
6. Conclusions and Recommendations
7. Security Considerations
8. Acknowledgements
9. References
10. Author's Addresses
11. IPR Notices
12. Copyright Statements
13. IANA Considerations
Document History
-00 This draft is intended as a study item for proposed future
work by the IETF in this area.
-01 Review of initial content, major edit and refinement of
concepts
-02 fairly important review; took out all new protocol reference;
added one author; added contribution on real implementation
-02 Added content to respond to 61st IETF comments;
refined ID goals; rewrote section 4.2 and 4.3; added cable
information.
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1. Introduction
The MPEG-2 stream is defined in the specification ISO/IEC 138181.
It provides a time-division multiplexed (TDM) stream that may
contain audio, video and data information. Each frame, known as
an MPEG-2 TS Packet, contains 4 bytes of header and 188 bytes of
data. The standard also defines the Transport Stream (TS)
packet. Each MPEG-2 TS Packet is associated with one Transport
Stream (TS) and is identified by a 13 bit Packet ID PID) carried
in the MPEG-2 TS Packet header.
The standard also defines a MPEG-2 control plane that may be used
to transmit control information. For example, specific
transmission information is sent to the senders/receivers using
System Information (SI) Tables (ETSI-SI, ETSI-SI1], or Program
Specific Information (PSI)Tables. The standard also allows
Defining tables that can be used to carry IP and PID information
about the transported stream. MPEG-2 address resolution assigns
IP addresses to particular transmission multiplexes, and within
a multiplex to a specific PID. The protocol signals this mapping
to the other communicating devices. In some address resolution
schemes, this address space is sub-divided into logical contexts
known as Platforms or Sections. One use of this sub-division is
to associate a separate context with each IP service provider that
shares a common MPEG-2 TS (uses the same PID).
MPEG-2 Receivers may optionally be assigned a Network Point of
Attachment (NPA) to uniquely identify the L2 node within the
MPEG-2 transmission network. An example of an NPA is the IEEE
Medium Access Control(MAC) address. Where such addresses are
used, these must also be signalled by the address resolution
procedure. Finally, address resolution may need to signal the
format of the data being transmitted. For example, the
encapsulation used or any compression scheme that was used at
the sender [ID-IPDVB-ARCH].
This document describes current mechanisms and their usage to
signal the TS Multiplex, the PID, and (if used) the MAC address
or platform ID associated with each IP address or flow to the
network layer at the sender and receiver. As will be seen below
this can, for example, be implemented via descriptors sent in
MPEG-2 SI tables via one or more new SI tables, or in-band
by a protocol using a data channel similarly to the IPv4 Address
Resolution Protocol, ARP, or IPv6 Neighbour Discovery (ND)
protocol.
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2. Conventions used in this document
AIT: Application Information Table specified by the Multimedia
Home Platform (MHP) specifications [ETSI-MHP]. This table may
carry IPv4/IPv6 to MPEG-2 TS address resolution information.
ATSC: Advanced Television Systems Committee [ATSC]. A set of
framework and associated standards for the transmission of video,
audio, and data, using the ISO MPEG-2 standard.
DVB: Digital Video Broadcast [ETSI-DVB]. A set of framework and
associated standards for the transmission of video, audio, and
data, using the ISO MPEG-2 standard.
DVB-RCS: Digital Video Broadcast Return Channel via Satellite.
A bi-directional IPv4/IPv6 service employing low-cost Receivers.
INT: Internet/MAC Notification Table. A uni-directional
addressing resolution mechanism using SI and/or PSI Tables.
MAC: Medium Access and Control of the Ethernet IEEE 802 standard
of protocols (see also NPA).
MHP: Multimedia Home Platform. An integrated MPEG-2 multimedia
receiver, that may (in some cases) support IPv4/IPv6 services.
MMT: Multicast Mapping Table (proprietary extension to DVB-RCS).
MPE: Multiprotocol Encapsulation [ETSI-DAT, ETSI-DAT1]. A scheme
that encapsulates Ethernet frames or IP Packets, creating a
DSM-CC Section. The Section will be sent in a series of TS Packets
over a TS Logical Channel.
MPEG-2: A set of standards specified by the Motion Picture Experts
Group (MPEG), and standardized by the International Standards
Organisation (ISO/IEC 113818-1) [ISO-MPEG2], and ITU-T (in H.220).
NPA: Network Point of Attachment. Addresses primarily used for
station (receiver) identification within a local network (e.g.
IEEE MAC address).
NPA: Network Point of Attachment. In this document, refers to a 6
byte destination address (resembling an IEEE MAC address) within
the MPEG-2 transmission network that is used to identify individual
Receivers or groups of Receivers.
PID: Packet Identifier[ISO-MPEG2]. A 13 bit field carried in the
header of TS Packets. This is used to identify the TS Logical
Channel to which a TS Packet belongs [ISO-MPEG2]. The TS Packets
forming the parts of a Table Section, PES, or other Payload Unit
must all carry the same PID value.
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The all 1s PID value indicates a Null TS Packet introduced
to maintain a constant bit rate of a TS Multiplex. There is no
required relationship between the PID values used for TS Logical
Channels transmitted using different TS Multiplexes.
PRIVATE SECTION: A syntactic structure constructed in accordance
with Table 2-30 of [ISO-MPEG2]. The structure may be used to
identify private information (i.e. not defined by [ISO-MPEG2])
relating to one or more elementary streams, or a specific MPEG-2
program, or the entire Transport Stream. Other Standards bodies,
e.g. ETSI, ATSC, have defined sets of table structures using the
private_section structure. A Private Section is transmitted as a
sequence of TS Packets using a TS Logical Channel. A TS Logical
Channel may carry sections from more than one set of tables.
PSI: Program Specific Information [ISO-MPEG2]. PSI is used to
convey information about services carried in a TS Multiplex.
It is carried in one of four specifically identified table
section constructs [ISO-MPEG2], see also SI Table.
RECEIVER (in the UDL context): A router or a host that has receive
only connectivity to a UDL.
SI TABLE: Service Information Table. In this document, the term is
used to describe any table used to convey information about the
service carried in a TS Multiplex (e.g. [ISO-MPEG]). SI tables are
carried in MPEG-2 private sections.
TS: Transport Stream [ISO-MPEG], a method of transmission at the
MPEG-2 level using TS Packets; it represents level 2 of the
ISO/OSI reference model.
See also TS Logical Channel and TS Multiplex.
TS LOGICAL CHANNEL: Transport Stream Logical Channel. In this
document, this term identifies a channel at the MPEG-2 level [ISO-
MPEG2]. It exists at level 2 of the ISO/OSI reference model. All
packets sent over a TS Logical Channel carry the same PID value
(this value is unique within a specific TS Multiplex). According to
MPEG-2, some TS Logical Channels are reserved for specific
signalling. Other standards (e.g., ATSC, DVB) also reserve specific
TS Logical Channels.
TS MULTIPLEX: In this document, this term defines a set of MPEG-2 TS
Logical Channels sent over a single lower layer connection. This may
be a common physical link (i.e. a transmission at a specified symbol
rate, FEC setting, and transmission frequency) or an encapsulation
provided by another protocol layer (e.g. Ethernet, or RTP over IP).
The same TS Logical Channel may be repeated over more than one TS
Multiplex (possibly associated with a different PID value) [ID-
ipdvb-arch], for example to redistribute the same multicast content
to two terrestrial TV transmission cells.
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TS PACKET: A fixed-length 188B unit of data sent over a TS
Multiplex [ISO-MPEG2]. Each TS Packet carries a 4B header,
plus optional overhead including an Adaptation Field, encryption
details and time stamp information to synchronise a set of
related TS Logical Channels.
UDL: Unidirectional link: A one-way transmission IP over DVB link,
e.g., a broadcast satellite link.
3. Address Resolution Requirements
The general IP over MPEG-2 AR requirements are summarized below;
These requirements are generic, enable the usage of network layer
protocols and will be used to evaluate existing approaches:
- Use SI tables for non-static allocation to promote AR scaling.
- Provide mechanisms to install AR information at the server
(unsolicited registration).
- Provide incremental table updates or purging of stale information.
- Support address scoping.
- Provide security associations to authenticate the AR information.
The MPEG IP address resolution is independent of encapsulation
and supports existing IP over MPEG-2 (e.g., MPE [ETSI-DAT,
ETSI-DAT1]) and also any IETF encapsulation that may be defined
[ID-IPDVB-ARCH].
A MPEG-2 Transmission Network may support multiple IP networks.
If this is the case, it is important to recognise the context
(scope) within which an address is resolved, to prevent packets
from one addressed scope leaking into other scopes. Examples of
overlapping IP address assignments include:
(i) Private unicast addresses (e.g. in IPv4, 10/8 prefix;
172.16/12 prefix; 192.168/16 prefix) should be confined to
one addressed area.
(ii) Some multicast addresses, (e.g., the scoped multicast
addresses sometimes used in private networks). These are
only valid within an addressed area (examples for IPv4
include; 239/8; 224.0.0/24; 224.0.1/24). Similar cases
exist for some IPv6 multicast addresses.
(iii) Scoped multicast addresses. Forwarding of these addresses
is controlled by the scope associated with the address.
IP packets with these addresses must not be allowed to travel
outside their intended scope, and may cause unexpected behaviour
if allowed to do so.
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In addition, overlapping address assignments can arise when using
Level 2 Network Point of Attachment (NPA) addresses [ID-IPDVB-
ARCH]:
(i) The NPA address must be unique within the addressed area.
IEEE MAC addresses used in Ethernet LANs are globally
unique. If the NPA addresses are not globally unique,
the same NPA address may be re-used by receivers in
different addressed areas.
(ii) The NPA broadcast address (all 1 MAC address). Traffic
with this address should be confined to one addressed area.
(iii) Other non-IP protocols may also view sets of MAC multicast
addresses as link-local, and may produce unexpected results
if distributed across several private networks.
3.1 Unicast Support
Reception of unicast packets destined for another addressed area
may lead to an increase in the rate of received packets by systems
connected via the network. IP end hosts normally filter received
unicast IP packets based on their assigned IP address.
Reception of the additional network traffic may contribute to
Processing load but should not lead to unexpected protocol
behaviour. It does however introduce a potential Denial of Service
(DoS) opportunity.
When the Receiver acts as an IP router, the receipt of such packet
may lead to unexpected protocol behaviour. This also provides a
security vulnerability since arbitrary packets may be passed to
the IP layer.
3.2 Multicast Support
There are specific issues concerning IPv4 and IPv6 multicast over
MPEG-2 Transmission Networks:
(i) Mapping IP multicast groups to the underlying MPEG-2 TS
Logical Channel (PID) and the MPEG-2 TS Multiplex.
(ii) Provide signalling information to allow a receiver to
locate an IP multicast flow within an MPEG-2 TS Multiplex.
(iii) Determining group membership (e.g. utilising IGMP/MLD).
Appropriate procedures need to be specified to identify the
correct action when the same multicast group is available on
separate TS Logical Channels. This could arise when different end
hosts act as senders to contribute IP packets with the same IP
group destination address.
Another different case arises when a receiver may potentially
receive more than one copy of the same packet. In some cases,
these may be sent in different TS Logical Channels, or even
different TS Multiplexes. In this case, at the IP level, the
host/router may be unaware of this duplication.
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The primary goal of multicast support will be efficient filtering
of IP-multicast packets by the receiver, and the mapping of IPv4
and IPv6 multicast addresses onto the associated PID value and TS
Multiplex. The design should permit a large number of active
multicast groups, and should minimise the processing load at the
receiver when filtering and forwarding IP multicast packets. For
example, schemes that may be easily implemented in hardware would
be beneficial, since these may relieve the drivers and operating
systems from discarding unwanted multicast traffic.
4. MPEG-2 Address Resolution
In this section, current MPEG-2 address resolution mechanisms are
reviewed.
4.1 Static configuration.
The static mapping option (IP addresses or flows statically mapped
to PIDs) is the equivalent to signalling "out-of-band". The
application programmer, installing engineer, or user receives the
mapping via some outside means (not in the MPEG-2 TS). This is
useful for testing, experimental networks, small subnetworks and
closed domains.
A single "well-known" PID is a specialisation of this. This is the
scheme used by the well known DOCSIS protocol in cable modems.
This results in all IP traffic to be placed into the specified TS
stream. Section or MAC filtering may be used to differentiate
subnetworks.
4.2 Table-Based Address Resolution
The information about the set of MPEG-2 TS streams carried
over a TS Multiplex can be distributed via tables that are
assigned a specific and well-known set of PIDs. This design
requires access to and processing of the SI table
information [ETSI-SI, ETSI-SI1]. This scheme reflects
the complexity of delivering and co-ordinating the various TS
stream associated with multimedia TV. Because of its historical
usage, there is no direct support for IP mechanisms for
identification of the TS multiplex and PID in use for a particular
IP address. It is also important to highlight that a PID value is
unidirectional and does not define a virtual channel in the
ATM sense.
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A TS multiplex may provide PID information for IP services by
integrating additional information into the existing MPEG-2 tables,
or to define additional tables specific to the IP service. This
has a dual advantage:
(i) IP specific information can be obtained directly.
(ii) The mechanism uses an already standardised mechanism.
Examples of current implementations of systems for allowing
a MPEG-2 receiver to identify the appropriate PID and multiplex
used to transmit traffic to a specific IP address include:
(i) IP/MAC Notification Table (INT) in the DVB Data standard
[ETS_DAT]. This provides uni-directional address
resolution of IPv4/IPv6 multicast addresses to MPEG-2
TS.
(ii) Application Information Table (AIT) in the Multimedia
Home Platform (MHP) specifications [ETSI-MHP].
(iii) Multicast Mapping Table (MMT) an MPEG-2 Table employed
by some DVB-RCS systems to provide uni-directional
address resolution of IPv4 multicast addresses to MPEG-2
TS.
The MMT and AIT are used for specific applications. The INT is
DVB standardised and more general purpose. It supports both IPv4
and IPv6 and can be used in combination with the other tables. It
is the favoured choice of some members of the DVB community for
address management and is briefly described below.
4.2.1 IP/MAC Notification Table (INT) and its usage
The INT provides a mechanism for carrying information about the
location of IP/MAC flows within DVB networks. An IP/MAC Platform
represents a set of IP/MAC streams and/or receiver devices. Such a
Platform may span several transport streams within one or multiple
DVB networks and represents a single IP network with a harmonized
address space (i.e. one without address conflicts). The IP/MAC
Platform concept allows for the coexistence of several
non-harmonized IP/MAC address spaces on the same DVB network.
The INT allows "subnets" and fully specified single destination
addresses to make signalling bandwidth efficient and flexible as
required. The "subnet mask" (also for IPv6) can be given in full
form or in slash notation (e.g. /127), this supports IPv6
prefixes.
Multicast addresses can be given with or without source (address
or range), although if source address is given then only the slash
notation can be used for prefixes/subnets.
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In addition to identification and security descriptors the
following descriptors are used for address binding in INT tables:
(i) target_MAC_address_descriptor: The descriptor used to
describe a single or group of MAC addresses (and
their mask).
(ii) target_MAC_address_range_descriptor: May be used to
setup filters.
(iii) target_IP_address_descriptor: The descriptor
describing a single or group of IPv4 unicast or
multicast addresses (and their mask).
(iv) target_IP_slash_descriptor: Allows definition and
announcement of an IPv4 subnet.
(v) target_IP_source_slash_descriptor: Uses source and
destination addresses to target a single or group of
devices; could be used to define flows.
(vi) IP/MAC stream_location_descriptor: This descriptor
directly locates the IP/MAC stream in a DVB network.
The following descriptors provide corresponding functions for IPv6
addresses:
target_IPv6_address_descriptor
target_IPv6_slash_descriptor
and target_IPv6_source_slash_descriptor
In addition, the ISP_access_mode_descriptor allows definition if
the access to the ISP is done via an alternative non-DVB network
(hence another address is necessary).
The INT provides a set of descriptors to manage addressing in a
DVB network. Its drawbacks are that while the IP/MAC concept is
general enough there is still a need to manage the addressing
(and the traffic) at the PID level. It currently is defined only
for Multi-Protocol Encapsulation (MPE) and would need extension to
support other schemes. In addition the use of a centralized
management prevents the implementation of a more dynamic
scheme.
4.2.2 Multicast Mapping Table (MMT) and its usage
The Multicast Mapping Table (MMT) is an example employing an MPEG-2
level control table to communicate a set of multicast addresses and
their associated PID value. This table allows a DVB-RCS Forward
Link Subsystem (FLSS) to specify the mapping and Return Channel
Satellite Terminals (RCSTs) to determine the PID values are being
used by the traffic that need to be received. The MMT is not
currently a part of the DVB-RCS specification.
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4.2.3 Application Information Table (AIT) and its usage
The DVB Multimedia Home Platform (MHP) specification does not define
a specific AR function. However, the MHP Standard specifies an
Application Information Table (AIT) that each MHP Receiver monitors
to receive a variety of control information. The AIT is a DSMCC
format table that provides information about data broadcasts, the
required activation state of applications carried by a broadcast
stream, etc. This information allows the broadcaster to request that
the receiver change the activation state of an application, and to
direct applications to receive specific multicast packet flows
(using IPv4 or IPv6 routing descriptors. In MHP, AR is not seen as
specific function, but a part of a wider configuration and control
function.
4.2.4 Comparison of table based approaches
All tables meet the specified requirements of the groups that
created them and all have their strength: the INT in terms of
flexibility and extensibility, the MMT in its simplicity, the AIT in
its extensibility. However, they exhibit scalability constraints,
encourage the development of technology specific solutions and do
not fully adopt IP-centric approaches that would enable easier use
of the MPEG-2 bearer as a link technology within the wider Internet.
5. Mapping IP addresses to NPA/MAC addresses
This section reviews IETF protocols that may be used to assign and
manage the mapping of IP addresses to/from NPA/MAC addresses.
Two IETF-defined protocols for mapping IP addresses to NPA/MAC
addresses are ARP and ND for IPv4 and IPv6 respectively. Both
protocols are normally used in a bi-directional mode, although
both also permit unsolicited transmission of mappings, which could
potentially be used in a uni-directional environment.
The use of ARP does not raise specific issues with the MPEG-2
Table-based AR for MPEG-2 Transmission Network Virtual Logical
Channels, since ARP uses only broadcast and unicast addresses.
The use of ND requires a multicast mapping of the set of
addresses used by ND to one or more MPEG-2 Transmission Network
Virtual Logical Channels.
<<< Some text is required to describe operational experience >>>
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5.1 Link Layer Support
This section considers two layer 2 issues that need to be
considered. One is the code-point to be used at L2 and the
other is the efficiency of encapsulation for transmission
to utilise the AR method. The table below summarises the
options for both MPE and ULE encapsulations.
+------------------------------+--------+----------------------+
| | PDU |L2 Frame Header Fields|
| L2 Encapsulation |overhead+----------------------+
| |[bytes] |src mac|dst mac| type |
+------------------------------+--------+-------+-------+------+
|a. ULE without dst MAC address| 8 | - | - | x |
|b. ULE with dst MAC address | 14 | - | x | x |
|c. MPE without LLC/SNAP | 16 | - | x | - |
|d. MPE with LLC/SNAP | 24 | - | x | x |
|e. ULE with Bridging extension| 22 | x | x | x |
|f. ULE with Bridging & NPA | 28 | x | x | x |
|g. MPE+LLC/SNAP+Bridging | 38 | x | x | x |
+------------------------------+--------+-------+-------+------+
Table of L2 support and overhead (x=supported, -=not supported)
a. ULE with no dst MAC/NPA address
<< to be written>>
b. ULE with dst MAC/NPA address
The IPv4 Address Resolution Protocol (ARP) [RFC826] uses
an IANA-assigned EtherType and is supported with ULE [IP-IPDVB-ULE].
The ND protocol of IPv6 [RFC2461] may be used.
<< More info on use of ND is required, noting that in one
form of header there is no MAC src address>>
c. MPE without LLC/SNAP
MPE does not provide an IANA-assigned EtherType and therefore
can not support the Address Resolution Protocol (ARP) [RFC826].
The ND protocol of IPv6 [RFC2461] may be used.
<< More info on use of ND is required, noting that in one form
of header there is no MAC src address>>
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d. MPE with LLC/SNAP
The LLC/SNAP format of MPE provides an IANA-assigned EtherType and
therefore may support the Address Resolution Protocol (ARP)
[RFC826]. There is no specification to define how this is
performed. In its simplest form, no MAC source address is present
in the L2 frame.
LLC/SNAP format MPE frames may optionally carry and IEEE bridging
header [LLC]. This header supplies both a MAC source and destination
address, at the expense of larger encapsulation overhead.
The ND protocol of IPv6 [RFC2461] may be used.
<< More info on the use of ND is required, noting that in one form
of header there is no MAC src address>>
5.2 Impact on Network Protocols when using Bi-directional
Transmission
<<< Other real implementation experience is requested: >>>
<<< Please send any experience to ipdvb list >>>
<<< text on DHCP, L2TP, PPoE, etc to be added by
other volunteers >>>
5.3 Impact on Network Protocols when using Uni-directional
Transmission
The IP over DVB link is basically a Uni-Directional broadcast
(UDL). ARP and ND do not work in their normal form over
such links, because these protocols assume the bi-directional
layer 2 connectivity. The UDL receiver cannot send any response
to a querier over the UDL link.
To solve this, we propose to use the UDLR (RFC3077)link layer
tunneling mechanism. UDLR emulates the UDL as a
bi-directional broadcast type link at the datalink layer. The
uni-directional functionality is hidden to IP and upper layer
protocols.
This section introduces how to use UDLR link layer tunneling
mechanisms to use ARP and ND on Uni-Directional DVB links
and shows the results of the evaluation of the combinations
of UDLR and various IP over DVB encapsulation protocols.
<<< Will be completed later, inputs required from WG >>>
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5.4 Cable Networks
Cable networks use different transmission schemes for the upstream
and downstream transmission. They do not usually employ table based
approaches for address resolution. Until the deployment of DOCSIS
and EuroDOCSIS most address resolution schemes in cable networks
for IP traffic have been proprietary and are still used for
some STB requiring interaction. In last case it is the role of
specific headend equipment to act as gateways between
cable set-top boxes and the Internet. These gateways receive STB
layer 2 information and allocate IP addresses; there is no
use of inband tables.
The information is sent (on the downstream) to the STBs as
IP/Ethernet encapsulated as MPEG frames on a well known PID.
DOCSIS uses only one PID. On the upstream, traffic is handled
just like any Ethernet frames and not as IP/Ethernet over MPEG-2.
While this approach is widespread, other roprietary schemes are
still used.
In the DOCSIS world, Cable Modem Terminal Systems (CMTSs) act as
DHCP servers and allocate IP addresses to DOCSIS modems and STBs.
DOCSIS acts as an Ethernet bridge between the Cable Modem and the
CMTS. The CMTS transparently proxies DHCP requests on behalf of a
DHCP server on the network. The DHCP option is "giadd" (Gateway
Internet Address)also called a "helper address", which is usually
the address of a real DHCP server. From the point of view of
modems and attached devices, it appears that the CMTS (default
gateway/router)is also the DHCP server.
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6. Conclusions and Recommendations
This document has examined addressing and address resolution
issues concerning the use of IP protocols over MPEG-2 transmission
networks. A number of specific IETF protocols are discussed along
with their expected behaviour over MPEG-2 transmission networks
and recommendations for usage.
In current MPEG-2 networks, the bindings between IP addresses and
PIDs can be done statically (such as in the cable
networks) or carried in tables such at the standard AIT in MHP,
the IP Notification Tables (INT) of DVB and the DVB-RCS
Multicast Mapping Tables (MMT). This document has reviewed
the status of these current address resolution mechanisms
in MPEG-2 networks, defined their usage and proved information
to identify what would be needed to improve their conformity
to standard IP practices.
Limitations of the current methods include the dynamics of
the table refresh support for IP scoping of addresses, a generic
access method for ARP and ND using the ULE encapsulation and the
lack of a universal and generic table access methodology.
7. Security Considerations
The normal security issues relating to the use of wireless links
for transport Internet traffic should be considered. Readers are
also referred to the known security issues associated with ARP
RFC826] and ND. Consideration will be given to those methods that
will ensure that usage of MPEG-2 network resources will be
restricted to IP addresses that are not a threat to those
resources or other resources in the Internet.
8. Acknowledgments
The authors wish to thank Rod Walsh, Jun Takei, Alexander Adolf,
Michael Mercurio and the ipdvb WG members for their inputs.
The authors would also like to acknowledge the support of the
European Space Agency.
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9. References
9.1 Normative References
[ATSC] A/53C, "ATSC Digital Television Standard", Advanced
Television Systems Committee (ATSC), Doc. A/53C, 2004.
[ATSC-DAT] A/90, "ATSC Data Broadcast Standard", Advanced
Television Systems Committee (ATSC), Doc. A/090, 2000.
[ATSC-DATG] A/91, "Recommended Practice: Implementation Guidelines
for the ATSC Data Broadcast Standard", Advanced Television Systems
Committee (ATSC),Doc. A/91, 2001.
[ATSC-A92] A/92 "Delivery of IP Multicast Sessions over ATSC Data
Broadcast", Advanced Television Systems Committee (ATSC),
Doc. A/92, 2002.
[ATSC-G] A/54A, "Guide to the use of the ATSC Digital Television
Standard", Advanced Television Systems Committee (ATSC),
Doc. A/54A, 2003.
[ATSC-PSIP-TC] A/65B, "Program and System Information Protocol for
Terrestrial Broadcast and Cable", Advanced Television Systems
Committee (ATSC), Doc. A/65B, 2003.
[ETSI-DAT] EN 301 192, "Specifications for Data
Broadcasting", v1.3.1, European Telecommunications Standards
Institute (ETSI), May 2003. http://www.etsi/org/
[ETSI-DAT1] EN 101 202, "Implementation Guide for Data", v1.2.1,
European Telecommunications Standards Institute (ETSI), May 2003.
http://www.etsi/org/
[ETSI-MHP] ETSI TS 101 812, "Digital Video Broadcasting (DVB);
Multimedia Home Platform (MHP) Specification", v1.2.1, European
Telecommunications Standards Institute (ETSI), June 2002.
http://www.etsi/org/
[ETSI-SI] ETSI EN 300 468: "Digital Video Broadcasting (DVB);
Specification for Service Information (SI) in DVB systems".
[ETSI-SI1] ETSI TR 101 162: "Digital Video Broadcasting (DVB);
Allocation of Service Information (SI) codes for DVB systems".
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[ID-IPDVB-ARCH] Montpetit, M.J., Fairhurst, G., Clausen, H.D.,
Collini-Nocker, B., and H. Linder, "Architecture for IP transport
over MPEG-2 Networks", Internet Draft, draft-ipdvb-arch-00.txt,
February 2005, Work in Progress, IPDVB WG.
[ID-MMUSIC-IMG] Y. Nomura, R. Walsh, J-P. Luoma, J. Ott, H.
Schulzrinne, "Protocol Requirements for Internet Media Guides",
nternet Draft, draft-ietf-mmusic-img-req-07.txt, June 2004, Work
in Progress,MMUSIC WG.
[ISO-DSMCC] ISO/IEC IS 13818-6 "Information technology -- Generic
coding of moving pictures and associated audio information -- Part
6: Extensions for DSM-CC is a full software implementation",
International Standards Organisation (ISO).
[RFC826] Plummer, D. "An Ethernet Address Resolution Protocol",
RFC 826, IETF, November 1982.
[RFC1122] B. Braden, ed., "Requirements for Internet Hosts -
Communication Layers", RFC 1122.
[RFC1112] Deering, S.E., "Host Extensions for IP Multicasting",
RFC1112, (STD05), IETF. August 1989.
[RFC2461] Narten, T., Nordmark, E., and W. Simpson, "Neighbor
Discovery for IP Version 6 (IPv6), RFC 2461, December 1998.
[RFC2464] Crawford. M., "Transmission of IPv6 Packets over
Ethernet Networks", RFC2464, IETF December 1998.
9.2 Informative References
[ETSI-DAT] EN 301 192 Specifications for Data Broadcasting,
European Telecommunications Standards Institute (ETSI).
[ETSI-DVBC] EN 300 800 Digital Video Broadcasting (DVB); DVB
interaction channel for Cable TV distribution systems (CATV),
European Telecommunications Standards Institute (ETSI).
[ISO-MPEG] ISO/IEC DIS 13818-1:2000 "Information technology ?
Generic coding of moving pictures and associated audio
information: Systems", International Standards Organisation (ISO).
[ETSI-DAT] EN 301 192 Specifications for Data Broadcasting,
European Telecommunications Standards Institute (ETSI).
http://www.atsc.org/standards/Code_Point_Registry.pdf
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10. Authors' Addresses
Godred Fairhurst
Department of Engineering
University of Aberdeen
Aberdeen, AB24 3UE
UK
Email: gorry@erg.abdn.ac.uk
Web: http://www.erg.abdn.ac.uk/users/gorry
Marie-Jose Montpetit
MJMontpetit.com
Email: marie@mjmontpetit.com
Hidetaka Izumiyama
President CEO, Wishnet Inc.
5-15-5-001 Shirokanedai, Minato-ku
Tokyo, 108-0071, Japan
Email: izu@wishnet.co.jp
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Disclaimer of Validity
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
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Copyright (C) The Internet Society (2004). This document is
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13. IANA Considerations
NOT KNOWN AT THIS TIME.
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