Internet DRAFT - draft-josyula-dhc-multicast
draft-josyula-dhc-multicast
INTERNET-DRAFT Ramakanth Josyula
Intended Status: Proposed Standard Brocade Communications
Expires: April 05, 2014 October 02, 2013
DHCP Option for IPTV Source address
draft-josyula-dhc-multicast-02.txt
Abstract
Internet Protocol Television(IPTV) is a system facilitating
transmission of television channels as multicast streams use
dedicated multicast group addresses in IP networks. Internet Group
Multicast Protocol(IGMP) is widely used for the communication between
hosts and routers to deliver the multicast streams in the IPv4
networks. Similarly,Multicast Listener Discovery Protocol (MLD)is
used for the communication between the hosts and routers to deliver
the multicast streams in the IPv6 networks. It is also possible for
the networks to distinguish these multicast streams not only by their
destination multicast group but also by the source IP address of the
streams. IGMP version-3 and MLD version-2 are protocols that allow
the hosts to inform the neighboring routers about their desire to
receive the multicast streams from specific source IP addresses.
This needs a mechanism to supply the available multicast source
address information to the hosts and the hosts also should be
strictly implemented with the source specific multicasting aware
protocols such as above mentioned IGMPv3 or MLDv2. This document
describes a new DHCP option which can addresses these issues. In
addition to this, the document also describes about the advantages in
the networks by implementing this option.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
provisions of BCP 78 and BCP 79.
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2 Background . . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.1 Topology . . . . . . . . . . . . . . . . . . . . . . . 3
1.2.2 Network behavior . . . . . . . . . . . . . . . . . . . 4
1.2.3 Limitations . . . . . . . . . . . . . . . . . . . . . . 4
2. DHCP IPTV Source Address Option . . . . . . . . . . . . . . . . 4
2.1 DHCP IPTV Source Address Option in IPv4 . . . . . . . . . . 4
2.2 DHCP IPTV Source Address Option in IPv6 . . . . . . . . . . 5
3 Server and client behavior . . . . . . . . . . . . . . . . . . 5
4 Advantages . . . . . . . . . . . . . . . . . . . . . . . . . . 6
5 Security Considerations . . . . . . . . . . . . . . . . . . . . 7
6 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 7
7 References . . . . . . . . . . . . . . . . . . . . . . . . . . 7
7.1 Normative References . . . . . . . . . . . . . . . . . . . 7
7.2 Informative References . . . . . . . . . . . . . . . . . . 8
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8
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1 Introduction
1.1 Terminology
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119].
1.2 Background
Many broad band service providers all across the world are delivering
triple play or multi play solutions. IPTV Solution is widely
integrated as part of these solutions.In many cases this service is
run by delivering multicast streams to the IP hosts/Set top boxes
connected to the home gateways. IGMP protocol in IPv4 networks and
MLD protocol in IPv6 networks are commonly used for requesting these
multicast streams from the nearest router connected via an access
network. Below sections will explain the typical topology and
functionality in most of the traditional access networks. The MLD
protocol follows the same mechanism in IPv6 networks of IGMP in IPv4.
In-order to reduce the complexity, the rest of the discussion in the
document is made with reference to IGMP only. MLD specific issues
are quoted wherever it is required. Further, wherever IGMP version-3
is referred, it is implied that can pointed to the MLD version-2 in
IPv6 networks.
1.2.1 Topology
+---------------+ |
Aggregation| | |-----Modem1/HomeGW-- Host-|- Host A
LAN | | Access | Lan |- Host B
| | Node-1 | |- Host C
|-----| |-- |
| | |...
+---------+ | +---------------+
| DHCP |--|
| Server | |
+---------+ |
|
| +---------------+
+---------+ | | |----- Modem2/----- Host D
| Layer-3 | | | Access | HomeGW
| Switch |--|-----| Node-2 |
| OR | | | |----- Modem3/----- Host E
| Router | | | |... HomeGW
| | +---------------+
+---------+
Figure 1: Triple play soution access network
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1.2.2 Network behavior
When any of the hosts starts(eg.power-on)initially, it will do a DHCP
discover/request to get an IP address to interact with the network.
DHCP server in the network will assign a unicast IP address to the
host. The nearest router will be sending IGMP general query messages
for every query interval time to check if any of the hosts are
interested in multicast service. If the host is interested in
receipt of a multicast channel, it will send an IGMP membership
report message towards the router. The router will forward the
multicast streams destined to the requested multicast group towards
the user interface. When the IGMP version-3 is implemented in the
network, the user will send the IGMP report message to include or
exclude particular multicast sources from the network. Router will
forward the multicast streams ONLY from the sources requested by the
user.
1.2.3 Limitations
For the implementation IGMPv3 or for upgrading the networks to
IGMPv3, the below additional requirements are to be met by the
network elements:
1. The network should build a mechanism that supplies the multicast
source address information to the hosts.
2. The hosts should be capable of distinguishing the multicast
streams based on the source IP address from which they are
originated.
3. The hosts should strictly follow IGMP version-3 mechanism for
exchanging IGMP messages with the network elements.
The new option described in the below sections can effectively
address these issues.
2. DHCP IPTV Source Address Option
The "IPTV Source Address" option specifies a list of IPTV source IP
addresses available or accessible to the hosts for receiving the
multicast streams. These source IPs can be listed in the option in
the order of any criteria such as quality of service or specific
service level agreements (SLAs)etc.
2.1 DHCP IPTV Source Address Option in IPv4
Below figure shows the option format:
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Code Len Address 1 Address 2
+-----+-----+-----+-----+-----+-----+-----+-----+--
| TBD | n | a1 | a2 | a3 | a4 | a1 | a2 | ...
+-----+-----+-----+-----+-----+-----+-----+-----+--
The minimum length of the option is 4 bytes.
The length of the option should be in the multiples of 4.
2.2 DHCP IPTV Source Address Option in IPv6
Below figure show the option format:
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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| (option code)TBD | option-len(n) |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IP Address-1 |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| |
| IP Address-2 |
| |
| |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| ... |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
The minimum length of this option would be 16Bytes and the length of
the option would be in the multiples of 16.
3 Server and client behavior
In case of IPv4 networks, the defined "IPTV Source Address option"
field will be filled by the DHCP server while sending the DHCP
acknowledgement packet to the client. Client can also send a DHCP
inform message to the DHCP server, requesting this parameter.
Similarly, incase of IPv6 networks, this option can be included in
the DHCP solicit, advertise, request, renew, rebind, Information-
request and reply. The clients can also request this option by
including this in the Options Request Option(ORO).
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The server will be pre-configured by the multicast source address
information by the administrator as per the SLA/policy or any such
criteria specific to the multicast users.
The clients will use the source addresses obtained from the server
while interacting with the routers using IGMPv3 or MLDv2.
If the hosts are still using older versions of IGMP/MLD protocols
which are not capable of requesting or distinguishing the multicast
traffic based on the source IP address, this is also possible that
the intermediate access nodes can snoop the DHCP messages and keep
the record of the list of source addresses provided to the host. By
using this information, the access nodes can filter the multicast
streams on behalf of the hosts. This snooping information can also
be used to authenticate the users for accessing the multicast service
from various multicast sources in the network.
4 Advantages
By addressing the issues mentioned in the section 1.1.3, the
implementation of this option in the network provides various
advantages to the network.
- It provides an effective method for maintaining and updating the
multicast source address information to every multicast host in the
network as per their individual SLAs.
- Intermediate access nodes can snoop this option from the DHCP
messages to extend the its multicast services like :
- Forwarding the multicast streams only to the authorized users
- Acting on behalf of the older clients which are non source aware
protocol versions (like IGMPv1/v2 and MLDv1) and make them
integrated with the latest source specific multicast networks
with IGMPv3/MLDv2 implementations.
- Convergence of IPTV services from different users can be achieved
at the user level irrespective of the multicast transmitting
technologies used in the network.For example,any service provider
who manages the aggregation and access networks can receive the
multicast streams from different sources/networks (may not be under
their own administration) and feed them to their access networks.
- The subscribers can easily validate the quality of the service
offered by different IPTV sources dynamically and switch to the
interested source as per their own set of requirements.
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5 Security Considerations
All the security considerations mentioned in rfc2131 (Dynamic Host
Control Protocol) are applicable for this document.If any malpractice
or mal function in DHCP may effect further transmission of multicast
traffic in the network.
6 IANA Considerations
IANA is requested to assign the option for multicast source address
for the registry maintained for DHCP.
7 References
7.1 Normative References
[RFC3376] Cain, B., Deering, S., Kouvelas, I., Fenner, B., and A.
Thyagarajan, "Internet Group Management Protocol, Version 3", RFC
3376, October 2002.
[RFC2236] Fenner, W., "Internet Group Management Protocol, Version
2", RFC 2236, November 1997.
[RFC1112] Deering, S., "Host extensions for IP multicasting", STD 5,
RFC 1112, August 1989.
[RFC2131] Droms, R., "Dynamic Host Configuration Protocol", RFC 2131,
March 1997.
[RFC2132] Alexander, S. and R. Droms, "DHCP Options and BOOTP Vendor
Extensions", RFC 2132, March 1997.
[RFC1700] Reynolds, J. and J. Postel, "Assigned Numbers", RFC 1340,
July 1992
[SSM] Holbrook, H. and B. Cain, "Source-Specific Multicast for
IP", RFC 4607, August 2006.
[MLDv2] Vida, R. and L. Costa, "Multicast Listener Discovery
Version 2 (MLDv2) for IPv6", RFC 3810, June 2004.
[RFC2710] Deering, S., Fenner, W., and B. Haberman, "Multicast
Listener Discovery (MLD) for IPv6", RFC 2710, October
1999.
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7.2 Informative References
Authors' Addresses
Ramakanth Josyula,
Brocade Communications Systems Pvt Ltd,
Vrindavan Tech Village - Special Economic Zone,
Devarabeesanahall Village, Varthur Hobli,
Bangalore,
India - 560037
Phone: +91 9591631444
EMail: josyular@brocade.com;ramakanthjosyula@gmail.com;
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