One document matched: draft-zhang-pim-muiimp-00.txt
PIM Working Group Hong-Ke Zhang
Internet Draft Shuai Gao
Intended status: Standards Track Beijing Jiaotong University
Expires: September 10, 2013 T C.Schmidt
HAW Hamburg
Bo-hao Feng
Li-Li Wang
Beijing Jiaotong University
March 11, 2013
Multi-Upstream Interfaces IGMP/MLD Proxy
draft-zhang-pim-muiimp-00.txt
Abstract
In this document, followed by the idea mentioned in [4] and
subsequent update in [5], an IGMP/MLD proxy with multiple upstream
interfaces called MUIIMP is proposed and analyzed. The MUIIMP
inherits the basic rule of the IGMP/MLD proxy but extends with
multiple upstream interfaces. To avoid data redundancy, each
upstream interface of an MUIIMP device MUST NOT send or subscribe
the same data simultaneously.
Requirements Language
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 [RFC2119].
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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Internet-Draft Multi-Upstream Interfaces IGMP/MLD Proxy March 2013
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Table of Contents
1. Introduction..................................................3
2. Terminology...................................................3
3. MUIIMP Behavior...............................................4
3.1. The selection of default upstream interface................5
3.2. Report of downstream subscriptions to upstream interfaces..5
3.3. Handover of the upstream interface.........................6
4. Security Considerations.......................................6
5. References....................................................6
Acknowledgment...................................................8
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1. Introduction
RFC 4605 [1] specifies an IGMP/MLD proxy mechanism for forwarding
based solely upon IGMP/MLD membership information in scenarios where
multicast routing is not available. According to [1], an IGMP/MLD
Proxy performs the router portion of the IGMP/MLD protocol on its
downstream interfaces, and the host portion of the IGMP/MLD protocol
on its single upstream interface.
The IGMP/MLD proxy mechanism can effectively extend the multicast
scope and greatly simplify the implementation of edge devices.
However, the IGMP/MLD proxy may exhibit inefficiency in some
specific scenarios due to the limitation of single upstream
interface. For example, in PMIPv6 multicast environment, multiple
IGMP/MLD proxy instances need to be deployed at the MAG in [6],
which may result in tunnel convergence problem. In addition, there
are also requirements to extend the IGMP/MLD proxy to support
multiple upstream interfaces as the emergence of multi-homing.
One thing to note is the idea about multiple upstream interfaces for
IGMP/MLD proxy was firstly proposed in the draft [4] to improve the
performance of mobile multicast source. The Multimob working group
draft [5] includes the related latest descriptions. Considering the
multiple upstream interfaces extension is not only required for
mobile multicast sources scenarios, this document is presented here.
In this document, an IGMP/MLD proxy with multiple upstream
interfaces called MUIIMP is proposed and described. The MUIIMP
inherits the basic rule of the IGMP/MLD proxy but extends with
multiple upstream interfaces. To avoid data redundancy, each
upstream interfaces of an MUIIMP device MUST NOT send or subscribe
the same data simultaneously. The MUIIMP is designed to support
local multicast listeners and senders.
2. Terminology
Upstream Interface: A proxy device's interface in the direction of
the root of the tree.
Downstream Interface: Each of a proxy device's interfaces that is
not in the direction of the root of the multicast tree.
Default upstream interface: An upstream interface which is by
default associated with each downstream node subscribing or sending
specific channel (group address prefix) or special multicast state.
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3. MUIIMP Behavior
The MUIIMP inherits the basic rule of the IGMP/MLD proxy but extends
with multiple upstream interfaces. A MUIIMP device has one or more
upstream as well as downstream interfaces, which may be any type
interfaces, including physical or logical interfaces.
The MUIIMP performs the router portion of the IGMP/MLD protocol on
its downstream interfaces, and the host portion of IGMP/MLD on its
upstream interfaces. The MUIIMP device MUST NOT perform the router
portion of IGMP/MLD on its upstream interfaces.
The MUIIMP device maintains a database for multicast listeners
consisting of the merger of all subscriptions on any downstream
interface. In order to avoid the redundant multicast traffic, the
proxy device should initiate unique traffic subscriptions. Besides,
a policy list that records the default upstream interface for the
downstream nodes is held for the selection of upstream interface.
In the following, the MUIIMP device behavior will be discussed
according the role of the downstream nodes.
1) Multicast listener on the downstream interface
Multicast listener reports are group-wise aggregated by the MLD
proxy. The aggregated report is issued to the upstream interface
based on the subscriptions as well as the policy list. When
receiving the IGMP/MLD subscriptions on the downstream interface,
the MUIIMP checks the membership database to make a decision whether
sends IGMP/MLD membership reports on the corresponding default
upstream interface or not. Refer to Section 3.2 for the details
about membership subscriptions lookup and report decisions.
When receiving packets on its upstream interfaces, the MUIIMP
forwards the traffic to all the downstream interfaces based upon the
downstream interfaces' subscriptions.
2) Multicast source on the downstream interface
When receiving packets on its downstream interface, the MUIIMP
forwards the traffic to the corresponding default upstream interface,
as well as all the downstream interfaces other than the incoming
interface based upon the downstream interfaces' subscriptions.
The (first) multicast router(s) operating multicast routing protocol
like PIM-SM[7]connected to the outside multicast domain should be
configured to treat the multicast source inside the MUIIMP domain
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being directly connected. Otherwise, it will discard the data due to
the failure of the direct connection check.
3.1. The selection of default upstream interface
Typically, the choice of the default upstream interface is based on
the policy list which is maintained at the MUIIMP.
The expression of the policy list is like below:
(node prefix, multicast group address/multicast state, upstream
interface)
Here node prefix represents the address prefix of the node on the
downstream interface that may be a multicast listener or multicast
source. And the multicast group address indicates the channel that
the multicast listener is subscribing or the multicast source is
publishing while the multicast state is only valid for listeners
indicating the state about both multicast source and multicast group
they are subscribing.
In other word, in the MUIIMP, the multicast group address/multicast
state and the node prefix will act as rules to select the default
upstream interface. Alternate configurations (e.g., the MAG-LMA
tunnel interface in PMIPv6 environment) MAY be applied.
3.2. Report of downstream subscriptions to upstream interfaces
To avoid the redundant multicast traffic, the proxy device MUST NOT
send the same multicast subscription record on different upstream
interfaces simultaneously. In detail, we recommend the following
rules when receiving an IGMP/MLD subscription on the downstream
interface.
1) If the received IGMP/MLD subscription is new and has not been
subscribed by other downstream multicast listeners, the proxy
device SHOULD initiate the IGMP/MLD subscription on the
corresponding default upstream interface.
2) If there exists the same IGMP/MLD subscription which has already
been subscribed by other downstream multicast listener, the proxy
device SHOULD not initiate extra IGMP/MLD subscription.
3) If there exists IGMP/MLD subscriptions which have already
included the received IGMP/MLD subscription, the proxy device
SHOULD not initiate extra IGMP/MLD subscription.
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4) If there exists overlapping subsets between the received IGMP/MLD
subscription and current IGMP/MLD subscriptions, the proxy device
SHOULD initiate the IGMP/MLD subscription on the corresponding
default upstream interface excluding the overlapping subsets that
have been subscribed before.
All subscriptions sent on the same upstream interface SHOULD be
merged according the merging rule in RFC 4605. In addition, the
local multicast source should be excluded in the final subscriptions
to avoid replicated multicast traffic from outside.
3.3. Handover of the upstream interface
If an upstream interface fails for some reason such as the deletion
of the tunnel interface in mobile environment, the handover of the
upstream interface is performed. Generally, all the subscriptions
sent on the previous invalid upstream interface are transferred to
the new valid upstream interfaces which are chosen among the default
upstream interfaces of the corresponding downstream nodes. The
choice may be made based on the predefined policy (e.g., the
interface priority, the number of listeners, the lowest IP address).
An alternative may be applied by the MUIIMP device itself according
to the traffic monitored or some strategies configured by the
operator.
4. Security Considerations
To be done.
5. References
[1] B. Fenner, H. He, B. Haberman and H. Sandick. "Internet Group
Management Protocol (IGMP) / Multicast Listener Discovery
(MLD)-Based Multicast Forwarding ("IGMP/MLD Proxying")", RFC
4605, August 2006.
[2] Cain, B., Deering, S., Kouvelas, I., Fenner, B. and A.
Thyagarajan, "Internet Group Management Protocol, Version3",
RFC 3376, October 2002.
[3] Vida, R. and L. Costa, "Multicast Listener DiscoveryVersion 2
(MLDv2) for IPv6", RFC 3810, June 2004.
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[4] Hong-Ke Zhang, Zhi-Wei Yan, Shuai Gao, etal.,"Multicast Source
Mobility Support in PMIPv6 Network", draft-zhang-multimob-msm-
03, July 2011.
[5] T C. Schmidt, S. Gao, H. Zhang, M. Waehlisch,"Mobile Multicast
Sender Support in Proxy Mobile IPv6 (PMIPv6) Domains", draft-
ietf-multimob-pmipv6-source-02, October2012.
[6] T. Schmidt, M. Waehlisch and S. Krishnan. "Base Deployment
forMulticast Listener Support in Proxy Mobile IPv6 (PMIPv6)
Domains", RFC 6224, April 2011.
[7] Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
"Protocol Independent Multicast - Sparse Mode (PIM-SM):
Protocol Specification (Revised)", RFC 4601, August 2000.
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Authors' Addresses
Hong-Ke Zhang, Shuai-Gao, Bo-Hao Feng, Li-Li Wang
National Engineering Lab for NGI Interconnection Devices
Beijing Jiaotong University, China
Phone: +861051684274
Email:hkzhang@bjtu.edu.cn
shgao@bjtu.edu.cn
11111021@bjtu.edu.cn
liliwang@bjtu.edu.cn
Thomas C. Schmidt
HAW Hamburg
Berliner Tor 7
Hamburg 20099
Germany
Email: schmidt@informatik.haw-hamburg.de
URI: http://inet.cpt.haw-hamburg.de/members/schmidt
Acknowledgment
Funding for the RFC Editor function is currently provided by the
Internet Society.
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