IPPM L. Deng Internet-Draft Z. Cao Intended status: Informational China Mobile Expires: April 21, 2014 October 18, 2013 Problem Statement for IP measurement in mobile networks draft-deng-ippm-wireless-00.txt Abstract This document analyzes the potential problems of applying existing IP-based performance measurement methods to wireless accessing environments. It suggests that more robust passive measuring methods and performance metrics are needed. 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 April 21, 2014. Copyright and License Notice Copyright (c) 2013 IETF Trust and the persons identified as the 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. Deng & Cao Expires April 21, 2014 [Page 1] Internet-DrafProblem Statement for IP measurement in mobile October 2013 Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Motivation . . . . . . . . . . . . . . . . . . . . . . . . . 2 2.1. Dynamic Load Balancing . . . . . . . . . . . . . . . . . 3 2.2. Radio Congestion Detection . . . . . . . . . . . . . . . 4 3. Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 4. Security Considerations . . . . . . . . . . . . . . . . . . . 5 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 6. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 6.1. Normative References . . . . . . . . . . . . . . . . . . 5 6.2. Informative References . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction It is well-accepted that mobile Internet usage is going to increase fast in the coming years and replace the traditional voice service to be the dominant revenue source for mobile operators. In the meantime, fast evolving network and terminal technologyies and changing service trend (e.g. social networking, video on demand, online reading, etc.) results in higher user service requirement. Therefore, as the basic infrastruture service provider, operators are deemed responsible for mobile Internet end-to-end performance, for subscribers want to get what they want, which gives rise to a basic yet important question: how does network service provider manage end- to-end service quality? In particular, there are two goals for operator's quality management intiative: o to make sure and validate the QoS metrics of specific IP flows agains the values pre-defined by the service SLA(Service Level Agreement) from the user/service provider's point of view; and o to make sure and validate the sanity of network devices/links. In this draft, we analyze two usecases the potential problems of applying existing IP-based performance measurement methods to wireless accessing environments, which are tending to utilize resouce pooling and dynamic load balancing techques to accommodate explosively increasing data traffic, and conclude that more robust passive measuring methods and performance metrics are needed. 2. Motivation Deng & Cao Expires April 21, 2014 [Page 2] Internet-DrafProblem Statement for IP measurement in mobile October 2013 2.1. Dynamic Load Balancing Pooling technology has been introduced to the user plane in the packet switched domain of operator's core network for cellular subscribers since 3GPP Release 5 (3GPP TS23.236). With pooling, the traffic path from user equipements to the Internet via core network is not static, but rather dynamically assigned to a proper instantce of an device pool, according to load balancing policies. The assignment is dynamically made at the time of user equipment's attachment establishement with the celluar core network, and would remain unchanged unless the mobile terminal detaches from the network or moves outside the base-stations' coverage subordinating to the specific core network's device pool. As shown by Figure 1, potential device pools along the path all the way from the user terminal via the packet switching domain of the mobile network core to a third party service provider over the Internet. Examples of network devices that can be poolized includeSGSN(Serving GPRS Support Node) and GGSN(Gateway GPRS Supporting Node). Moreover, the service provider could also implement load balancing on the server's side either via server- pooling within a data certer or via (third party) CDN nodes. Radio |Packet |Internet Access |Switching | Network |Core Network | | +--------+ +----+---+ +--------+ | |+------+| |+------+| |+------+| | +-->|SGSN_1|+------->|GGSN_1|+--+ ||SERV_1|| | | |+------+| |+------+| | |+------+| +--+ +--+--+ +-----+ | | | | | | | | | |---->| +--->| +--+ |+------+| |+------+| | |+------+| |UE| |NodeB| | RNC | ||SGSN_2|| ||GGSN_2|| +---->|SERV_2|| | |....>| |...>| |... |+------+| |+------+| |+------+| +--+ +--+--+ +-----+ . | | | | | | | . | ... | | ... | | ... | | . |+------+| |+------+| |+------+| +--------------------+ ...>|SGSN_N|........>|GGSN_M|........>|SERV_K|| | Injected Traffic | |+------+| |+------+| |+------+| | ---------------> | +--------+ +----+---+ +--------+ | Actual Traffic | | | ...............> | | +--------------------+ Figure 1: Active Measuring Traffic versus Actual Traffic in case of Device Pooling Deng & Cao Expires April 21, 2014 [Page 3] Internet-DrafProblem Statement for IP measurement in mobile October 2013 Hence, under such environments, if active performance measurement methods[RFC4656][RFC5357] are employed, the injected bogus data traffic may traverse along a different path to the one used by the targeted traffic or even interfere with them due to the subtle nature of wireless-involved links (as explained in the next subsection). 2.2. Radio Congestion Detection Mobile Internet usage is going to increase fast in the coming years due to the following facts: on one hand, as a result of pervasively deployed and fast maturing 3G/4G cellular technologies combined with smartphone's dominance in mobile handset's market, Internet data traffic via mobile operator's packet switched core network manifests to be an increasingly important contributor to the operator's revenue. On the other hand, wireless technologies (such as WiFi through APs or celluar networks through small cells) are more and more accepted by the end users, either at home, in the office or in a pulic place, to be carring the "last mile" to various portable personal computing devices. There are two common features of the above two scenarios: o the combination of both wireless and wired links along the end-to- end traffic path, and o almost all the time, the wireless "last mile" would be the bottleneck of end-to-end service quality. To make more efficient use of relatively more scarce radio resouces, it is important for the core network to understand the congestion status of both wireless and wired links along the traffic path, and make proper management of data traffic through cell reselection or load balancing via pooling. However, the wireless link's thoughput is consistently subject to other interfereing factors (e.g. distance to the nearest base station, terminal's radio signal strength, random interferece, shadowing of buildings, multipath fading, etc.), which should be properly filtered out before handing over to the network management, as they are rooted in terminal mobility and outside the realm of mobile accessing network. In other words, there is considerable gap between IP measurement results to the performance evaluation and fault detection requirements in mobile-involved environment, if we directly employ active performance measurement methods[I-D.draft-chen-ippm-coloring-based-ipfpm-framework]. Deng & Cao Expires April 21, 2014 [Page 4] Internet-DrafProblem Statement for IP measurement in mobile October 2013 3. Summary In summary, for mobile-ended data paths, we believe there is need for o viable passive measurement methodology for Active measurements inject extra traffic, which may traverse along a different path to the one used by the targeted traffic or even interfere with them. o robust metric against transient wireless conditions, as there is considerable gap between existing IP measurement metrics (e.g. delay, jitter, throughput etc.), which are subject to change caused by external environmental factors and of little use to operator's traffic management from the network side. 4. Security Considerations TBA 5. IANA Considerations None. 6. References 6.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC2234] Crocker, D., Ed. and P. Overell, "Augmented BNF for Syntax Specifications: ABNF", RFC 2234, November 1997. 6.2. Informative References [I-D.draft-chen-ippm-coloring-based-ipfpm-framework] Chen, M., Liu, H., Yin, Y., Papneja, R., Abhyankar, S., and G. Deng, "Coloring based IP Flow Performance Measurement Framework", draft-chen-ippm-coloring-based- ipfpm-framework-00 (work in progress), July 2013. [RFC4656] Shalunov, S., Teitelbaum, B., Karp, A., Boote, J., and M. Zekauskas, "A One-way Active Measurement Protocol (OWAMP)", RFC 4656, September 2006. [RFC5357] Hedayat, K., Krzanowski, R., Morton, A., Yum, K., and J. Babiarz, "A Two-Way Active Measurement Protocol (TWAMP)", RFC 5357, October 2008. Deng & Cao Expires April 21, 2014 [Page 5] Internet-DrafProblem Statement for IP measurement in mobile October 2013 Authors' Addresses Lingli Deng China Mobile Email: denglingli@chinamobile.com Zhen Cao China Mobile Email: caozhen@chinamobile.com Deng & Cao Expires April 21, 2014 [Page 6]