MBONED Working Group Percy S. Tarapore Internet Draft Robert Sayko Intended status: BCP AT&T Expires: January 15, 2014 Greg Shepherd Toerless Eckert Cisco Ram Krishnan Brocade July 15, 2013 Multicasting Applications Across Inter-Domain Peering Points draft-tarapore-mboned-multicast-cdni-03.txt Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. Internet-Drafts are working documents of the Internet Engineering Task Force (IETF), its areas, and its working groups. Note that other groups may also distribute working documents as Internet- Drafts. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." 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Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Abstract This document examines the process of transporting applications via multicast across inter-domain peering points. The objective is to describe the setup process for multicast-based delivery across administrative domains and document supporting functionality to enable this process. Table of Contents 1. Introduction...................................................2 2. Overview of Inter-domain Multicast Application Transport.......3 3. Inter-domain Peering Point Requirements for Multicast..........4 3.1. Native Multicast..........................................4 3.2. Peering Point Enabled with GRE Tunnel.....................6 3.3. Peering Point Enabled with an AMT - Both Domains Multicast Enabled........................................................7 3.4. Peering Point Enabled with an AMT - AD-2 Not Multicast Enabled........................................................9 4. Supporting Functionality......................................11 4.1. Network Transport and Security Guidelines................11 4.2. Routing Aspects and Related Guidelines...................11 4.3. Back Office Functions - Billing and Logging Guidelines...11 4.4. Operations - Service Performance and Monitoring Guidelines12 4.5. Reliability Models/Service Assurance Guidelines..........12 4.6. Provisioning Guidelines..................................12 4.7. Client Models............................................12 4.8. Addressing Guidelines....................................12 5. Security Considerations.......................................12 6. IANA Considerations...........................................12 7. Conclusions...................................................13 8. References....................................................13 8.1. Normative References.....................................13 8.2. Informative References...................................13 9. Acknowledgments...............................................13 1. Introduction Several types of applications (e.g., live video streaming, software downloads) are well suited for delivery via multicast means. The use of multicast for delivering such applications offers significant Tarapore, et al Expires January 15, 2014 [Page 2] IETF I-D Multicasting Applications Across Peering Points July 2013 savings for utilization of resources in any given administrative domain. End user demand for such applications is growing. Often, this requires transporting such applications across administrative domains via inter-domain peering points. The objective of this Best Current Practices document is twofold: o Describe the process and establish guidelines for setting up multicast-based delivery of applications across inter-domain peering points, and o Catalog all required information exchange between the administrative domains to support multicast-based delivery. While there are several multicast protocols available for use, this BCP will focus the discussion to those that are applicable and recommended for the peering requirements of today's service model, including: o Protocol Independent Multicast - Source Specific Multicast (PIM-SSM) [RFC4607] o Internet Group Management Protocol (IGMP) v3 [RFC4604] o Multicast Listener Discovery (MLD) [RFC4604] This document therefore serves the purpose of a "Gap Analysis" exercise for this process. The rectification of any gaps identified - whether they involve protocol extension development or otherwise - is beyond the scope of this document and is for further study. 2. Overview of Inter-domain Multicast Application Transport A multicast-based application delivery scenario is as follows: o Two independent administrative domains are interconnected via a peering point. o The peering point is either multicast enabled (end-to-end native multicast across the two domains) or it is connected by one of two possible tunnel types: o A Generic Routing Encapsulation (GRE) Tunnel [RFC2784] allowing multicast tunneling across the peering point, or o An Automatic Multicast Tunnel (AMT) [IETF-ID-AMT]. o The application stream originates at a source in Domain 1. Tarapore, et al Expires January 15, 2014 [Page 3] IETF I-D Multicasting Applications Across Peering Points July 2013 o An End User associated with Domain 2 requests the application. It is assumed that the application is suitable for delivery via multicast means (e.g., live steaming of major events, software downloads to large numbers of end user devices, etc.) o The request is communicated to the application source which provides the relevant multicast delivery information to the EU device via a "manifest file". At a minimum, this file contains the {Source, Group} or (S,G) information relevant to the multicast stream. o The application client in the EU device then joins the multicast stream distributed by the application source in domain 1 utilizing the (S,G) information provided in the manifest file. The manifest file may also contain additional information that the application client can use to locate the source and join the stream. It should be noted that the second administrative domain - domain 2 - may be an independent network domain (e.g., Tier 1 network operator domain) or it could also be an Enterprise network operated by a single customer. The peering point architecture and requirements may have some unique aspects associated with the Enterprise case. The Use Cases describing various architectural configurations for the multicast distribution along with associated requirements is described in section 3. Unique aspects related to the Enterprise network possibility will be described in this section. A comprehensive list of pertinent information that needs to be exchanged between the two domains to support various functions enabling the application transport is provided in section 4. 3. Inter-domain Peering Point Requirements for Multicast The transport of applications using multicast requires that the inter-domain peering point is enabled to support such a process. There are three possible Use Cases for consideration. 3.1. Native Multicast This Use Case involves end-to-end Native Multicast between the two administrative domains and the peering point is also native multicast enabled - Figure 1. Tarapore, et al Expires January 15, 2014 [Page 4] IETF I-D Multicasting Applications Across Peering Points July 2013 ------------------- ------------------- / AD-1 \ / AD-2 \ / (Multicast Enabled) \ / (Multicast Enabled) \ / \ / \ | +----+ | | | | | | +------+ | | +------+ | +----+ | | CS |------>| BR |-|---------|->| BR |-------------|-->| EU | | | | +------+ | I1 | +------+ |I2 +----+ \ +----+ / \ / \ / \ / \ / \ / ------------------- ------------------- AD = Administrative Domain (Independent Autonomous System) CS = Content Multicast Source BR = Border Router I1 = AD-1 and AD-2 Multicast Interconnection (MBGP or BGMP) I2 = AD-2 and EU Multicast Connection Figure 1 - Content Distribution via End to End Native Multicast Advantages of this configuration are: o Most efficient use of bandwidth in both domains o Fewer devices in the path traversed by the multicast stream when compared to unicast transmissions. From the perspective of AD-1, the one disadvantage associated with native multicast into AD-2 instead of individual unicast to every EU in AD-2 is that it does not have the ability to count the number of End Users as well as the transmitted bytes delivered to them. This information is relevant from the perspective of customer billing and operational logs. It is assumed that such data will be collected by the application layer. The application layer mechanisms for generating this information need to be robust enough such that all pertinent requirements for the source provider and the AD operator are satisfactorily met. The specifics of these methods are beyond the scope of this document. Architectural Requirements for this Configuration: R3.1-1: Peering points between domains shall be at least dual homed for reliability with full BGP table visibility. Tarapore, et al Expires January 15, 2014 [Page 5] IETF I-D Multicasting Applications Across Peering Points July 2013 R3.1-2: If the peering point between AD-1 and AD-2 is a controlled network environment, then bandwidth can be allocated accordingly by AD-1 and AD-2 to permit the transit of non rate-adaptive multicast traffic, otherwise the multicast traffic should support rate- adaptation. R3.1-3: Each domain AD-1, AD-2 determines by local policy whether to permit sending and/or receiving of IP multicast traffic from the other domain. If AD-1 is for example a service provider and AD-2 an enterprise, then AD-1 may often only support traffic delivery to, but not traffic reception from AD-2. R3.1-4: Relevant information on the multicast streams delivered to End Users in AD-2 shall be collected at the application layer. The precise nature of the collected information will be driven by requirements set down by the source owner and the domain operators. 3.2. Peering Point Enabled with GRE Tunnel The peering point is not native multicast enabled in this Use Case. There is a Generic Routing Encapsulation Tunnel provisioned over the peering point. In this case, the interconnection I1 between AD-1 and AD-2 in Figure 1 is multicast enabled via a Generic Routing Encapsulation Tunnel (GRE) [RFC2784] and encapsulating the multicast protocols across the interface. The routing configuration is basically unchanged: Instead of BGP (SAFI2) across the native IP multicast link between AD-1 and AD-2, BGP (SAFI2) is now run across the GRE tunnel. Advantages of this configuration: o Highly efficient use of bandwidth in both domains although not as efficient as the fully native multicast Use Case. o Fewer devices in the path traversed by the multicast stream when compared to unicast transmissions. o Ability to support only partial IP multicast deployments in AD- 1 and/or AD-2. o GRE is an existing technology and is relatively simple to implement. Disadvantages of this configuration: Tarapore, et al Expires January 15, 2014 [Page 6] IETF I-D Multicasting Applications Across Peering Points July 2013 o Per Use Case 3.1, current router technology cannot count the number of end users or the number bytes transmitted. o GRE tunnel requires manual configuration. o GRE must be in place prior to stream starting. o GRE is often left pinned up Architectural Requirements for this Configuration: R3.2-1 through R3.2-4 are the same as requirements R.3.1-1 through R.3.1-4 defined in Use Case 3.1. R3.2-5: GRE tunnels will be manually configured at peering points to support multicast delivery between domains. R3.1-6 The GRE tunnel (tunnel server) in source network must be configured to only advertise the routes to the Content Sources (not the entire network). Otherwise content that should not be in tunnel may go through tunnel (e.g. content not part of an agreed CDN partnership). 3.3. Peering Point Enabled with an AMT - Both Domains Multicast Enabled Both administrative domains in this Use Case are assumed to be native multicast enabled here; however the peering point is not. The peering point is enabled with an Automatic Multicast Tunnel. The basic configuration is depicted in Figure 2. Tarapore, et al Expires January 15, 2014 [Page 7] IETF I-D Multicasting Applications Across Peering Points July 2013 ------------------- ------------------- / AD-1 \ / AD-2 \ / (Multicast Enabled) \ / (Multicast Enabled) \ / \ / \ | +----+ | | | | | | +------+ | | +------+ | +----+ | | CS |------>| AR |-|---------|->| AG |-------------|-->| EU | | | | +------+ | I1 | +------+ |I2 +----+ \ +----+ / \ / \ / \ / \ / \ / ------------------- ------------------- AR = AMT Relay AG = AMT Gateway I1 = AMT Interconnection between P-CDN and S-CDN I2 = S-CDN and EU Multicast Connection Figure 2 - AMT Interconnection between AD-1 and AD-2 Advantages of this configuration: o Highly efficient use of bandwidth in AD-1. o AMT is an existing technology and is relatively simple to implement. Attractive properties of AMT include the following: o Dynamic interconnection between Gateway-Relay pair across the peering point. o Ability to serve clients and servers with differing policies. Disadvantages of this configuration: o Per Use Case 3.1 (AD-2 is native multicast), current router technology cannot count the number of end users or the number bytes transmitted. o Additional devices (AMT Gateway and Relay pairs) may be introduced into the path if these services are not incorporated in the existing routing nodes. o Currently undefined mechanisms to select the AR from the AG automatically. Tarapore, et al Expires January 15, 2014 [Page 8] IETF I-D Multicasting Applications Across Peering Points July 2013 Architectural Requirements for this Configuration: R3.3-1 through R3.3-4 are the same as requirements R.3.1-1 through R.3.1-4 defined in Use Case 3.1. R3.3-5: AMT Relay and Gateway pair needs to be established at peering points to support multicast delivery between domains. The AMT tunnel will then configure dynamically across the peering point once the Gateway in AD-2 receives the (S,G) information from the EU. 3.4. Peering Point Enabled with an AMT - AD-2 Not Multicast Enabled In this AMT Use Case, the second administrative domain AD-2 is not multicast enabled. This implies that the interconnection between AD- 2 and the End User is also not multicast enabled as depicted in Figure 3. ------------------- ------------------- / P-CDN \ / S-CDN \ / (Multicast Enabled) \ / (Non-Multicast \ / \ / Enabled) \ | +----+ | | | | | | +------+ | | | +----+ | | CS |------>| AR |-|---------|-----------------------|-->|EU/G| | | | +------+ | | |I2 +----+ \ +----+ / \ / \ / \ / \ / \ / ------------------- ------------------- (Note: Diff-marks for the figure have been removed to improve viewing) CS = Content Source AR = AMT Relay EU/G = Gateway client embedded in EU device I2 = AMT Tunnel Connecting EU/G to AR in AD-1 through Non-Multicast Enabled AD-2. Figure 3 - AMT Tunnel Connecting AD-1 AMT Relay and EU Gateway This Use Case is equivalent to having unicast distribution of the application through AD-2. The total number of AMT tunnels would be equal to the total number of End Users requesting the application. The peering point thus needs to accommodate the total number of AMT Tarapore, et al Expires January 15, 2014 [Page 9] IETF I-D Multicasting Applications Across Peering Points July 2013 tunnels between the two domains. Each AMT tunnel can provide the data usage associated with each End User. Advantages of this configuration: o Highly efficient use of bandwidth in AD-1. o AMT is an existing technology and is relatively simple to implement. Attractive properties of AMT include the following: o Dynamic interconnection between Gateway-Relay pair across the peering point. o Ability to serve clients and servers with differing policies. o Each AMT tunnel serves as a count for each End User and is also able to track data usage (bytes) delivered to the EU. Disadvantages of this configuration: o Additional devices (AMT Gateway and Relay pairs) are introduced into the transport path. o Assuming multiple peering points between the domains, the EU Gateway needs to be able to find the "correct" AMT Relay in AD- 1. Architectural Requirements for this Configuration: R3.4-1 through R3.4-3 are the same as requirements R.3.1-1 through R.3.1-3 defined in Use Case 3.1. R3.4-4: Proper procedures shall exist to enable the AMT Gateway at End User device to find the correct AMT Relay in AD-1 across the peering points. At a minimum, the application client in the EU device will supply the (S,G) information to the Gateway for this purpose. R3.3-5: Relevant information on the multicast streams delivered to End Users in AD-2 via AMT tunnels shall be collected by the tunnels per existing AMT capabilities. A variation of this Use Case can be constructed as follows: o Single AMT tunnel across peering point. Tarapore, et al Expires January 15, 2014 [Page 10] IETF I-D Multicasting Applications Across Peering Points July 2013 o Strategic location of AMT Gateways at Exit Routers in AD-2 and an AMT Relay at AD-2 side of Peering Point. This reduces the total number of unicast streams across AD-2 equal to the total number of exit routers in AD-2. o Co-Location of AMT Relays with the AMT Gateways at the Exit Routers. This permits the AMT Gateway at the End User device application client to establish a shorter AMT tunnel with the AMT Relay at the appropriate Exit Router. The advantage for such a chained set of AMT tunnels is that the total number of unicast streams across AD-2 is significantly reduced thus freeing up bandwidth. The negative aspect is that several AMT tunnels will need to dynamically configure by the various AMT Gateways based solely on the (S,G) information received from the application client at the EU device. The requirements for this scenario are the same as the simpler case defined in this section. Only the dynamic configurations will become more complicated for setting up the correct set of tunnel chains. 4. Supporting Functionality Supporting functions and related interfaces over the peering point that enable the multicast transport of the application are listed in this section. Critical information parameters that need to be exchanged in support of these functions are enumerated along with guidelines as appropriate. Specific interface functions for consideration are as follows. 4.1. Network Transport and Security Guidelines 4.2. Routing Aspects and Related Guidelines 4.3. Back Office Functions - Billing and Logging Guidelines Tarapore, et al Expires January 15, 2014 [Page 11] IETF I-D Multicasting Applications Across Peering Points July 2013 4.4. Operations - Service Performance and Monitoring Guidelines 4.5. Reliability Models/Service Assurance Guidelines 4.6. Provisioning Guidelines In order to find right relay there is a need for a small/light implementation of an AMT DNS in source network. 4.7. Client Models 4.8. Addressing Guidelines 5. Security Considerations (Include discussion on DRM, AAA, Network Security) 6. IANA Considerations Tarapore, et al Expires January 15, 2014 [Page 12] IETF I-D Multicasting Applications Across Peering Points July 2013 7. Conclusions 8. References 8.1. Normative References [RFC2784] D. Farinacci, T. Li, S. Hanks, D. Meyer, P. Traina, "Generic Routing Encapsulation (GRE)", RFC 2784, March 2000 [IETF-ID-AMT] G. Bumgardner, "Automatic Multicast Tunneling", draft- ietf-mboned-auto-multicast-13, April 2012, Work in progress [RFC4604] H. Holbrook, et al, "Using Internet Group Management Protocol Version 3 (IGMPv3) and Multicast Listener Discovery Protocol Version 2 (MLDv2) for Source Specific Multicast", RFC 4604, August 2006 [RFC4607] H. Holbrook, et al, "Source Specific Multicast", RFC 4607, August 2006 8.2. Informative References 9. Acknowledgments Tarapore, et al Expires January 15, 2014 [Page 13] IETF I-D Multicasting Applications Across Peering Points July 2013 Authors' Addresses Percy S. Tarapore AT&T Phone: 1-732-420-4172 Email: tarapore@att.com Robert Sayko AT&T Phone: 1-732-420-3292 Email: rs1983@att.com Greg Shepherd Cisco Phone: Email: shep@cisco.com Toerless Eckert Cisco Phone: Email: eckert@cisco.com Ram Krishnan Brocade Phone: Email: ramk@brocade.com Tarapore, et al Expires January 15, 2014 [Page 14]