Network Working Group T. Li Internet-Draft Z. Sun Intended status: Standards Track H. Wang Expires: September 7, 2011 C. Jia NUDT Mar 6, 2011 Point to Multipoint Streaming Media Delivery for Edge Network Problem Statement draft-li-p2mpsmd-sam-problem-statement-00.txt Abstract Currently, more and more Internet streaming services are getting increasingly popular among users. With the increasing growth of streaming media traffic, network awareness and policy-based control are required for providing higher QoE to the end users and better OAM support to the service providers. They are especially important for point to multipoint streaming media delivery for the edge network. However, most of the existing technologies or protocols, such as IP multicast, do not provide the network aware and policy-based control mechanisms. This document presents the problem statements in point to multipoint streaming media delivery for edge network, explains why network awareness and policy-based control should be urgently addressed for the point to multipoint streaming media delivery in the edge network and introduces what's should be further considered in the future. 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). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. 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." This Internet-Draft will expire on September 7, 2011. Copyright Notice Copyright (c) 2011 IETF Trust and the persons identified as the Li, et al. Expires September 7, 2011 [Page 1] Internet-Draft Point to Multipoint Streaming Media Mar 2011 document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents carefully, as they describe your rights and restrictions with respect to this document. 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. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. Problem Statement Scope . . . . . . . . . . . . . . . . . . . . 4 4. Architecture Requirements . . . . . . . . . . . . . . . . . . . 6 4.1. Network-aware OAM support for streaming media service provider(SMSP) . . . . . . . . . . . . . . . . . . . . . . 6 4.2. QOE for better user experience . . . . . . . . . . . . . . 6 5. Why IETF needs to develop solutions instead of relying on existing technologies? . . . . . . . . . . . . . . . . . . . . 6 5.1. IP multicast . . . . . . . . . . . . . . . . . . . . . . . 7 5.2. Overlay(CDN P2P) . . . . . . . . . . . . . . . . . . . . . 7 5.3. Data-Oriented Network . . . . . . . . . . . . . . . . . . . 8 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 8 7. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . 8 8. Informative References . . . . . . . . . . . . . . . . . . . . 8 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 9 Li, et al. Expires September 7, 2011 [Page 2] Internet-Draft Point to Multipoint Streaming Media Mar 2011 1. Introduction Streaming traffic is among the fastest growing traffic on the Internet. As the streaming media delivery has characteristics of long-live connection and high stable transmission rate, the Internet capacity is imposed with stringent requirements of high bandwidth, low delay and jitter, and low packet loss. The situation is further complicated by frequent load variations from the dynamic behavior of large asynchronous clients. The current Internet faces many challenges from the core to the edge, as its end-to-end design principle with best-effort service cannot be well suited for point to multipoint (P2MP) streaming media delivery application. From an ISP's perspective, the Internet bandwidths are relatively scarce and precious resources, especially in the core network. When end-to-end unicast technology is used for the steaming media delivery over the Internet, a separated point-to-point connection (e.g., UDP/ TCP connections) is employed between the sender and each of the receivers. It leads to the poor use of the available bandwidth due to the multiple copies of streaming media object on the same link. It is desirable for ISP that an efficient P2MP delivery mechanism is established for delivering copies of the streaming media data to multiple recipients at different locations, in order to minimize the amount of the required network resources (in terms of bandwidth). From an end-user's perspective, quality of experience (QoE) is widely appreciated as an important subjective measurement for the streaming media delivery service, such as IPTV, VoD. Usually, the quality of service (QoS) metrics (such as network delay & jitter and packet loss), rather than QoE, is used for the objective measure of the streaming media delivery service. With the dramatic improvement in digital video quality (like High Definition) and the prevalence of streaming media applications, the Internet is facing with significant challenges in providing QoS insurance. It is essential to build an efficient P2MP streaming media delivery mechanism for an optimal end- user experience. The better the QoE is, the more likely the end- users subscribe streaming media service, which benefits both ISPs and the content providers. From a streaming media service provider's perspective, a service network requires efficient and low-cost deployment, maintenance and management. However, the existing distributed routing models and protocols for P2MP streaming media delivery cannot provide enough support to fulfill the above requirements. It is crucial for network fundamental infrastructure to provide efficient protocol and mechanisms, such that the service providers can effectively and automatically monitor, detect and troubleshoot performance issues in the service networks. Li, et al. Expires September 7, 2011 [Page 3] Internet-Draft Point to Multipoint Streaming Media Mar 2011 Much of the research and the dominant technical trend, such as CDN (Content Delivery Network) and IPTV, is to push the streaming media service from the core network to edge. The reason is, the main duty of core network in the Internet is designed to forward data as quickly as possible, i.e., to provide the best performance for packet forwarding service. It will be a great burden for the core network if providing various service-relevant processing supports. On the other hand, edge network provides information exchange between the access network and the core network. The bandwidth and throughput in the edge network are relatively low, which provide opportunities for the devices and facilities in the edge networks to integrate supportive functionality for P2MP streaming media delivery. However, the devices in the edge network usually have relative lower processing power and less intelligence, which poses challenges for the service provisioning of P2MP streaming media delivery. The motivation of this document is to clarify the problems facing the P2MP streaming media delivery for the edge network. 2. Terminology Qaulity of Experience (QoE): The overall acceptability of an application or service, as perceived subjectively by the end-user. Quality of Service (QoS): The collective effect of performance which determines the degree of satisfaction of a user of the service. Streaming Media Service Provider(SMSP): A company that offers delivering streaming media services such as providing video content, improving network performance, and enhancing transmission quality, etc. 3. Problem Statement Scope There are a number of problems related to the P2MP streaming media delivery for edge network. The two major issues are listed below. (1) The difficulty of network state information (NSI) acquisition. Unpredictable behaviors of users present unusual challenges to the edge network delivering P2MP streaming media. The links and nodes (routers and switches) in the network experience rapid and large- scale changes in bandwidth availability. Therefore, the congestion may occur frequently over time and space, which introduces delays and jitters to the flows of streaming media. That is adverse to the streaming media delivery due to its stringent demands on discontinuity-free and high stable transmission rate. Li, et al. Expires September 7, 2011 [Page 4] Internet-Draft Point to Multipoint Streaming Media Mar 2011 Network-aware streaming media delivery is an attractive approach to mitigate the problems. However, the exact information about the current condition of the network is hard to adapt the resource demands for QoS. Such information can be obtained at the transport protocol level or directly from the application. NSI acquisition at application level is widely accepted as it can be easily implemented and deployed. However, transport-level NSI acquisition can provide more accurate network status information while brings less overhead to the network. It compares very favorable to application-lever NSI acquisition in delivery timely and accurate information for supporting well-founded adaption decisions in monitoring, diagnostics and failure restoration. However, most transport protocols in TCP/IP stack implicitly gather the network performance metrics only for support embedded control mechanism, such as congestion control (TCP) or reliable transmission (RTP). These metrics (information) are currently not available to high-level applications. The fact that few of the transport-level protocols explicitly collect and provide the NSI, such as bandwidth and timestamp, makes QoS assurance of the P2MP streaming media delivery difficult. (2) The difficulty of policy-based control Most of the P2MP streaming delivery systems deployed in the edge network employ pull-based service model based on IP multicast technology. In this model, the streaming data are transmitted along the delivery paths which is decided or calculated according to the distribution of users' requests. However, other service models, such as push-based and pull-and-push based, are also very useful in providing different featured services to the end-users. For example, the subscribed advertisements, video messages and news can be directly delivered to the specific end-users without explicit requests under push-based service model. The model improves initiative and flexibility of P2MP streaming media delivery service, and provides technical support for the implementation of value-added services. Pull-and-push based service model can be very helpful in reducing the delivery time derived from the dynamic changes of users' request. For example of the IPTV service in the edge network, the channel zapping delay can be shortened, if the streaming data can be pushed to some intermediate nodes before the users pull the content. The different service models, i.e., pull-based, push-based and pull- and-push based model, can provide different optimized characteristic to the P2MP delivery service of streaming media. And, it will be significant if the three models can be implemented as different policies for the P2MP streaming media delivery in the edge network. The current delivery mechanisms, such as IP multicast, do not provide Li, et al. Expires September 7, 2011 [Page 5] Internet-Draft Point to Multipoint Streaming Media Mar 2011 policy-based control in the delivery process, as there is no clear separation between policies and functions in these mechanisms. This strictness makes providing policy-based optimized control of P2MP delivery difficult in the edge network, and it somehow disencourages the evolution, development and improvement of the streaming media delivery services. 4. Architecture Requirements 4.1. Network-aware OAM support for streaming media service provider(SMSP) Efficient OAM (Operation, Administration and Maintenance) support is fundamental for SMSP to provide high quality of experience to the end users. Network-aware OAM allows SMSP to take more intelligent decisions and adapt its streaming media delivery in response to network conditions. Timely and accurate information about network status is instrumental in making well-founded adaptation decisions by the OAM. Transport-level monitoring can satisfy the need very effectively and efficiently, as it can provide enough information while incurring less overhead on the edge network and the end- systems. Moreover, incremental deployment is an important architectural attribution required by SMSP. The cost of deployment, running, and maintaining can be reduced, if the efficient mechanisms for P2MP streaming media delivery in the edge network support incremental deployment. That means, new schemes and solutions should not modify the original fundamental infrastructure, and the update or the substitution can proceed smoothly. 4.2. QOE for better user experience From the user's viewpoint, QoE is the subjective feelings of the networks business service performance. For better QoE, fast failure Recovery, traffic engineering, load balance, quality adaption should be concerned in P2MP streaming media delivery. The architecture supporting the P2MP streaming media delivery should provide automatic mechanisms when an underlay link is down or congestion is appeared between two nodes. Continuity and quality should be ensured even when some congestions and failures occur in the network. 5. Why IETF needs to develop solutions instead of relying on existing technologies? Li, et al. Expires September 7, 2011 [Page 6] Internet-Draft Point to Multipoint Streaming Media Mar 2011 5.1. IP multicast IP multicast is the most effective technology to solve the bandwidth problem in streaming media transmission. Multicast reduces both network link cost and server bandwidth requirement for serving a large number of receivers simultaneously. In IP multicast, the source sends only one copy of a packet addressed to a group of receivers and the core network bandwidth will not increase with the numbers of receivers. Despite its clear performance benefit, multicast has not been wide deployment in the past years. The IP multicast issues related to scalability, reliability, deployment, etc. Routers keep every active group states and the message overhead and memory cost grow linearly with the number of multicast groups supported by the router. The UDP is used as the transport layer for IP multicast and it cannot provide reliable transport. However, UDP doesn't guarantee reliability or integrity, and there are no obvious signs indicating the sequence of packets in a UDP flow. The information carried by UDP header is deficient. There are also some problems with the demanding requirement of global deployment of multicast routers and the lack of appropriate pricing models. 5.2. Overlay(CDN P2P) P2P reduce the profit of ISP and violate the fairness principle for the business. ISP cannot benefit from offering service to the peers who wish to freely use ISP resources. P2P distribution just concerns the upper logic network rather than physical network states and topology, and a great deal of redundant streams pass over the core Internet. Moreover, P2P stream is hard to control and occupy network resources deucedly. In CDN architecture, the content is first distributed to CDN servers which are placed in many regions. CDN can provide reliable delivery and cost-effective scaling, but CDN costs more and it is hard to be deployed. Both P2P and CDN have their own limitations, so hybrid CDN and P2P have been proposed by many researchers. Hybrid CDN and P2P are the common techniques for live streaming and VoD applications. Hybrid Architecture is an effective way to reduce the cost of content distribution and guarantee the quality of transmission for streaming media service. Hybrid CDN and P2P architecture requires careful dimensioning and design, due to the different contribution policies, interrelated system parameters, and their impacts on multiple performance metrics. If the contribution policy is not adopted sensibly, the hybrid architecture neither can share the network resource nor reduce the overall cost. Li, et al. Expires September 7, 2011 [Page 7] Internet-Draft Point to Multipoint Streaming Media Mar 2011 5.3. Data-Oriented Network DON communication is completely different from the traditional IP network. In DON, delivery is driven by the content of data, rather than the host identifiers. This decouples the data delivery and request of host, the content can be cached by the network nodes in advance. The forwarding path is determined by looking up the content ID in the node and very little overhead is imposed. However, it can hardly be deployed into current Internet architecture gracefully. The technology is currently under research and the future of DON is still uncertain. 6. Security Considerations This document has no additional requirement for security. 7. Acknowledgments We would like to thank Jigang Wu and Guozhi Song for their valuable suggestions. 8. Informative References [1] "Appendix I to P.10/G.100: Definition of QoE", ITU-TP.10/ G. 100, Jan 2007. [2] "Telephone Network and ISDN Quality of Service, Network Management and Traffic Engineering: Terms and Definitions Related to Quality of Service and Network Performance Including Dependability", ITU-T Recommendation E. 800, Aug 1994. [3] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Application", RFC 1889, Jan 1996. [4] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Application", RFC 3550, July 2003. [5] Lao, L., Cui, J., Gerla, M., and D. Maggiorim, "A Comparative Study of Multicast Protocols: Top, Bottom, or In the Middle?", In Proceedings of INFOCOM' 2006. [6] Xu, D., Kulkarni, SS., and C. Rosenberg, "Analysis of a CDN-P2P hybrid architecture for cost-effective streaming media Li, et al. Expires September 7, 2011 [Page 8] Internet-Draft Point to Multipoint Streaming Media Mar 2011 distribution. Multimedia Systems", pp 383-399, Mar 2006. [7] Koponen, T., Chawla, M., and B. Chun, "A data-oriented (and beyond) network architecture.", ACM SIGCOMM 2007. Authors' Addresses Tao. Li NUDT 47 Yanwachi St Changsha China Phone: +86-13487568531 Email: taoli.nudt@gmail.com Zhi Gang. Sun NUDT 47 Yanwachi St Changsha China Phone: +86-13875903721 Email: sunzhigang@nudt.edu.cn Hui. Wang NUDT 47 Yanwachi St Changsha China Phone: +86-13467578342 Email: wanghuinudt@gmail.com Chun Bo. Jia NUDT 47 Yanwachi St Changsha China Phone: +86-13407318066 Email: jiachunbo1988@sina.com Li, et al. Expires September 7, 2011 [Page 9]