Multicast Geo-Distribution Control
draft-rekhter-geo-distribution-control-01
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| Document | Type | Active Internet-Draft (individual) | |
|---|---|---|---|
| Authors | Huajin Jeng , Jeffrey Haas , Yakov Rekhter | ||
| Last updated | 2012-07-05 | ||
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draft-rekhter-geo-distribution-control-01
Network Working Group Huajin Jeng
Internet Draft AT&T
Intended status: Standards Track
Expires: January 2013 Jeff Haas
Juniper Networks
Yakov Rekhter
Juniper Networks
Jeffrey (Zhaohui) Zhang
Juniper Networks
July 5 2012
Multicast Geo-Distribution Control
draft-rekhter-geo-distribution-control-01.txt
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Abstract
Consider a content provider that wants to deliver a particular
content to a set of customers/subscribers, where the provider and the
subscribers are connected by an IP service provider. This document
covers two areas needed to accomplish this: (1) providing the content
provider with the information of whether it can use the multicast
connectivity service provided by the IP service provider to deliver a
particular content to a particular set of subscribers, and (2)
providing the content provider with a mechanism to restrict delivery
of a given content to a particular set of the subscribers.
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Table of Contents
1 Specification of requirements ......................... 3
2 Introduction .......................................... 3
3 Overview of Operations ................................ 4
4 Multicast Distribution Reachability Signaling ......... 5
5 Multicast Distribution Control Signaling .............. 6
5.1 An example of configuration on ERs .................... 9
6 IANA Considerations ................................... 10
7 Security Considerations ............................... 10
8 Acknowledgements ...................................... 10
9 References ............................................ 10
9.1 Normative References .................................. 10
9.2 Informative References ................................ 10
10 Authors' Addresses .................................... 11
1. Specification of requirements
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].
2. Introduction
Consider a content provider that wants to deliver a particular
content to a set of customers/subscribers, where the provider and the
subscribers are connected by an IP service provider. This document
covers two areas needed to accomplish this: (1) providing the content
provider with the information of whether it can use the multicast
connectivity service provided by the IP service provider to deliver a
particular content to a particular set of subscribers, and (2)
providing the content provider with a mechanism to restrict delivery
of a given content to a particular set of the subscribers.
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For the purpose of this document we assume that a content provider
consists of one or more Content Servers, and one or more Content
Distribution Controllers. While this document assumes communication
between Content Servers and Content Distribution Controllers, the
procedures for implementing such communication is outside the scope
of this document.
Content Servers are connected to one or more IP service provider
(ISP) that can offer both multicast and unicast connectivity service
to the subscribers of the content provider. Content provider uses
this ISP(s) to deliver content to its subscribers.
Subscribers are connected to the Egress Routers (ERs) of the ISP.
Note that the multicast connectivity service provided by the ISP
extends all the way to the ERs. Such service could be provided by
either deploying IP multicast natively, or with some tunneling
mechanism like AMT, or by a combination of both within the ISP.
However, between the ERs and the subscribers there may, or may not be
multicast connectivity.
In the case where a particular subscriber of a given content provider
does not have multicast connectivity to its ER, the content provider
would use IP unicast service provided by the ISP to transmit the
particular content to that subscriber.
3. Overview of Operations
An ISP, using the procedures described in Section "Multicast
Distribution Reachability Signaling", provides a content provider,
and specifically Content Distribution Controller(s) of that content
provider, with the information of whether a particular subscriber of
that content provider has multicast connectivity to an ER of that
ISP.
For each content provided by a content provider, the content provider
maintains a list of subscribers who are either excluded or allowed to
receive the content. For the purpose of maintaining this list this
document assumes that subscribers are grouped into "zones", so that
exclusion/inclusion uniformly applies to all the subscribers within a
given zone. Procedures by which subscribers are grouped into zones
are outside the scope of this document. However, this document
assumes that this grouping is done consistently by both the content
provider and the ISP(s) that the content provider uses for delivering
its content.
To enforce the exclusion/inclusion policies, the content provider
uses procedures described in Section "Multicast Distribution Control
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Signaling".
For each content provided by a content provider, the content provider
selects a particular multicast channel (S, G) for distributing this
content using multicast connectivity service. Mapping between a
particular content and the multicast channel used for distributing
this content is maintained by both Content Server(s) and Content
Distribution Controller(s) of the content provider. Procedures by
which the content provider selects a particular multicast channel,
and maintains the mapping are outside the scope of this document.
When a subscriber wants to receive the particular content from its
content provider, the subscriber issues a request for this content to
the Content Distribution Controller of the provider. When the Content
Distribution Controller receives the request, the Content
Distribution Controller uses the information carried in the request
(e.g., IP address of the subscriber) to determine the zone of the
subscriber, and based on that zone to determine whether the
subscriber can receive this content.
If the Content Distribution Controller determines that the subscriber
can receive the content, then based on the information provided by
the multicast distribution reachability signaling the Content
Distribution Controller determines whether the subscriber can receive
this content using multicast connectivity service, and if yes, then
returns to the subscriber the multicast channel selected for
distributing the content.
If the Content Distribution Controller determines that the subscriber
can receive the content, but can not receive the content using
multicast connectivity service, the Content Distribution Controller
returns to the subscriber the information needed to receive this
content using unicast connectivity service.
Specification of the procedures for communication between subscribers
and Content Distribution Controllers are outside the scope of this
document.
4. Multicast Distribution Reachability Signaling
Multicast distribution reachability signaling is responsible for
giving a content provider, and specifically Content Distribution
Controller(s) of the content provider the information of whether a
particular subscriber of that content provider has multicast
connectivity to an ER of an ISP that the content provider uses for
distributing its content.
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This document assumes that each ER can determine the multicast
reachability status for each of the subscriber connected to that ER.
Procedures by which an ER accomplishes this are outside the scope of
this document.
To indicate whether a given ER has multicast reachability to a
subscriber (be that either a native multicast or AMT) this document
uses BGP as follows. An ER originates into IBGP routes for the
subscribers connected to that ER for which the ER has multicast
reachability. These routes are carried using BGP multi-protocol
capabilities [RFC4760] with AFI 1 or 2, and MCAST-REACH SAFI. The
NLRI field in the MP_REACH_NLRI/MP_UNREACH_NLRI attribute of these
routes contains subscribers' IP addresses encoded as IP address
prefixes. The value of the AFI field in the
MP_REACH_NLRI/MP_UNREACH_NLRI attribute of these routes determines
whether subscribers' addresses are IPv4 or IPv6 (AFI 1 indicates IPv4
addresses, AFI 2 indicates IPv6 addresses).
A Content Distribution Controller, when it receives such routes, uses
them to determine whether the content could be delivered to the
subscribers via the ISP who owns the ERs using the multicast
connectivity service provided by the ISP.
To constrain the flow of BGP routes that carry multicast distribution
reachability information such routes carry a particular Route Target
(RT) Extended Community [RFC4360], and Content Distribution
Controller(s) are provisioned to import routes with such RT.
RTs carried by routes with AFI 1 and MCAST-REACH SAFI SHOULD NOT be
re-used by routes with any other AFI and/or SAFI. Likewise, RTs
carried by routes with AFI 2 and MCAST-REACH SAFI SHOULD NOT be re-
used by routes with any other AFI and/or SAFI.
To facilitate such constrained distribution of multicast distribution
reachability information one MAY use Route Target Constrains
[RFC4684].
5. Multicast Distribution Control Signaling
Multicast distribution control signaling is intended to enforce
exclusion/inclusion policies of a content provider, and specifically
to prevent a subscriber from accessing a particular multicast channel
carrying a particular content provided by the content provider if the
subscriber obtained the information about this channel through some
illegitimate means.
Multicast distribution control signaling for a particular content is
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originated by Content Distribution Controller(s), and uses BGP Flow
Spec [RFC5575] as follows.
For a particular content carried over a particular (S, G) multicast
flow the Content Distribution Controller responsible for that content
originates a BGP Flow Spec route. This route is carried using BGP
multi-protocol capabilities [RFC4760] with AFI 1 (for IPv4) or 2 (for
IPv6), and MCAST-FLOWSPEC SAFI. The NLRI of the route carries S in
the Source Prefix component (with length of 32 for IPv4 or 128 for
IPv6), and G in the Destination Prefix component (with length of 32
for IPv4 of 128 for IPv6).
This route is ultimately propagated to the ER of the ISP connected to
the content provider.
An ER that receives BGP Flow Spec routes carrying the multicast
distribution control information applies it to PIM and/or IGMP
messages the ER receives from the subscribers connected to that ER.
Specifically, the ER, based on the information received in the BGP
Flow Spec routes, decides whether to accept (or reject) a particular
PIM or IGMP Join received on one of its subscriber's ports, as
follows.
Associated with each zone are two sets of RTs - one that controls
inclusion, and another than controls exclusion. This document assumes
that a content provider and the ISP(s) connected to that content
provider maintain consistent information about the RTs associated
with each zone. Procedures to accomplish this are outside the scope
of this document.
As a Content Distribution Controller originates a BGP Flow Spec route
for a particular (S, G) multicast flow, such a route will carry one
or more RTs, which will ultimately control inclusion/exclusion of
that flow on individual ports of ERs that receive this route.
Each subscriber port on an ER is associated with one or more zones.
For each zone that a port belongs to, the port is provisioned with
two sets of RTs associated with that zone - the inclusion set is for
allowing to accept PIM or IGMP Join for some content (or to be more
precise for the (S, G) flow that carries that content), and the
exclusion set is for disallowing to accept PIM or IGMP Joins for some
other content. All those RTs (of all subscribers ports) control
import of BGP Flow Spec routes by the ER.
If the RTs carried by a given BGP Flow Spec route carrying multicast
distribution control signaling match the inclusion set of RTs
associated with a given port on an ER, then PIM or IGMP Joins for the
(S, G) carried in the route and received from the subscriber(s)
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connected to that port SHOULD be accepted by the ER. If the RTs
carried by the route match the exclusion set, then PIM or IGMP Joins
for the (S, G) carried in the route MUST NOT be accepted when
received from the subscriber(s) connected to that port.
Each subscriber port on an ER is provisioned with the default
inclusion/exclusion policy that controls acceptance (or rejection) of
PIM or IGMP Join messages in the absence of any multicast
distribution control signaling. In the former case, in the absence of
any multicast distribution signaling, subscribers connected to that
port may receive any multicast flow. In the latter case, in the
absence of any multicast distribution control signaling, subscribers
connected to that port may receive no multicast flows. BGP Flow Spec
routes that carry multicast distribution control signaling modify
such default behavior.
Once a Content Distribution Controller determines that a particular
(S, G) multicast stream no longer used to carry a particular content,
the Content Distribution Controller withdraws the BGP Flow Spec route
that carries multicast distribution control information for that
content.
Note that while [RFC5575] uses the information carried in BGP Flow
Spec routes for the purpose of Data Plane filtering, this document
uses this information for the purpose of filtering multicast Control
Plane traffic (PIM or IGMP).
To constrain the distribution of BGP Flow Spec routes that carry
multicast distribution control information to only the relevant ERs,
the ERs MAY originate Route Target Constraint (RTC) routes that carry
the RTs that control import of the BGP Flow Spec routes on these ERs.
To constrain the import of these RTC routes to only the Content
Distribution Controllers, the Content Distribution Controllers are
configured with one or more RTs. These RTs control import by the
Content Distribution Controller(s) of the RTC routes originated by
the ERs. Furthermore, the Content Distribution Controllers MAY
themselves originate RTC routes that carry the import RT(s)
configured on these Content Distribution Controllers, and that
control import of RTC routes by these Content Distribution
Controllers.
This document assumes that if a given content provider has multiple
Content Distribution Controllers, then all of these Controllers are
provisioned with the same RT(s) that control import of the RTC routes
originated by the ERs. Furthermore, this document assumes that if a
given ISP is providing (multicast) connectivity service to more than
one content provider, then the RTC routes originated by any of the
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ERs of that ISP MUST carry the set union of the import RTs used by
the Content Distribution Controllers of all of these content
providers.
RTs carried by routes with AFI 1 and MCAST-FLOWSPEC SAFI SHOULD NOT
be re-used by routes with any other AFI and/or SAFI. Likewise, RTs
carried by routes wiht AFI 2 and MCAST-FLOWSPEC SAFI SHOULD NOT be
re-used by routes with any other AFI and/or SAFI. Furthermore, RTs
carried by routes with AFI 1 and SAFI 132 (AFI/SAFI used by RTC
routes) SHOULD NOT be re-used by routes with any other AFI and/or
SAFI.
Note that while [RFC4684] uses RTC routes to constrain distribution
of VPN-IP routes [RFC4364], this document uses RTC routes to
constrain distribution of BGP Flow Spec routes, and also to
(recursively) constrain distribution of RTC routes themselves.
5.1. An example of configuration on ERs
Consider an ER in Manhattan that has a port that is provisioned with
the following import RTs:
<include-manhattan, exclude-manhattan, include-nyc, exclude-nyc,
include-east, exclude-east, include-usa, exclude-usa>
When the ER receives a Flow Spec route with <exclude-nyc, include-
manhattan, include-usa> RTs, the ER first try to match "include-
manhattan" or "exclude-manhattan" (the first ones on the list) - and
the result is "include-manhattan". Therefore, the (S, G) carried in
the Flow Spec route is allowed on that port of the ER.
Consider another ER in Boston that has a port that is provisioned
wiht the following import RTs:
<include-brookline, exclude-brookline, include-bos, exclude-bos,
include-east, exclude-east, include-usa, exclude-usa>
The above mentioned Flow Spec route will be imported (due to the
include-usa RT), and will result in the (S, G) carried in the flow
Spec route to be allowed on that port of the ER.
Now consider a different Flow Spec route with the <exclude-usa,
include-bos, include-nyc, exclude-manhattan> RTs. The (S, G) carried
in the route will be disallowed in Manhattan, allowed in Boston, and
allowed in Queens (as the route will match the "include-nyc" RT).
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6. IANA Considerations
This document defines two new SAFIs - MCAST-REACH and MCAST-FLOWSPEC.
7. Security Considerations
TBD.
8. Acknowledgements
The authors would like to thank Han Nguyen for his contributions to
this document.
9. References
9.1. Normative References
[RFC2119] "Key words for use in RFCs to Indicate Requirement
Levels.", Bradner, March 1997
[RFC5575] "Dissemination of Flow Specification Rules", P. Marques, et
al., August 2009
[RFC4760] Bates, T., Rekhter, Y., Chandra, R., and D. Katz,
"Multiprotocol Extensions for BGP-4", RFC 4760, January 2007.
[RFC4360] Sangli, S., Tappan, D., and Y. Rekhter, "BGP Extended
Communities Attribute", RFC 4360, February 2006.
9.2. Informative References
[RFC4364] E. Rosen, Y. Rekhter, "BGP/MPLS IP Virtual Private Networks
(VPNs)", RFC4364, February 2006
[RFC4684] Pedro Marques, et al., "Constrained Route Distribution for
Border Gateway Protocol/MultiProtocol Label Switching (BGP/MPLS)
Internet Protocol (IP) Virtual Private Networks (VPNs)", RFC4684,
November 2006
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10. Authors' Addresses
Huajin Jeng
AT&T
e-mail: hj2387@att.com
Jeff Haas
Juniper Networks
Email: jhaas@juniper.net
Yakov Rekhter
Juniper Networks
Email: yakov@juniper.net
Jeffrey (Zhaohui) Zhang
Juniper Networks
Email: zzhang@juniper.net
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