Energy Aware Control Approach for QoS in heterogeneous packet access networks
Author(s): DH, Christoph Lange, Nico Bayer
This document describes an approach to enhance user perceived service quality by control protocols following potential network performance impairments in case of energy aware network operation....
Network Working Group D. von Hugo Internet-Draft N. Bayer Intended status: Informational C. Lange Expires: January 14, 2014 Telekom Innovation Laboratories July 12, 2013 Energy Aware Control Approach for QoS in heterogeneous packet access networks draft-vonhugo-eacp-hetnet-01 Abstract This document describes an approach to enhance user perceived service quality by control protocols following potential network performance impairments in case of energy aware network operation. 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. 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This document may contain material from IETF Documents or IETF Contributions published or made publicly available before November von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 1] Internet-Draft Energy Aware Control Approach for QoS July 2013 10, 2008. The person(s) controlling the copyright in some of this material may not have granted the IETF Trust the right to allow modifications of such material outside the IETF Standards Process. Without obtaining an adequate license from the person(s) controlling the copyright in such materials, this document may not be modified outside the IETF Standards Process, and derivative works of it may not be created outside the IETF Standards Process, except to format it for publication as an RFC or to translate it into languages other than English. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Conventions and Terminology . . . . . . . . . . . . . . . . . 4 3. Energy aware network model . . . . . . . . . . . . . . . . . . 5 3.1. Network model . . . . . . . . . . . . . . . . . . . . . . 5 3.2. Problem descrition . . . . . . . . . . . . . . . . . . . . 6 3.3. Solution space . . . . . . . . . . . . . . . . . . . . . . 7 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 12 7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 13 7.1. Normative References . . . . . . . . . . . . . . . . . . . 13 7.2. Informative References . . . . . . . . . . . . . . . . . . 13 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 14 von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 2] Internet-Draft Energy Aware Control Approach for QoS July 2013 1. Introduction Major challenge for carrier grade network operators trying to reduce power consumption in the access domain is to grant customer satisfaction in terms of only minimum degraded service quality. This requires the network to meet the specified and agreed performance figures demanded by various applications using network connectivity. Energy saving by load-adaptive provision of transmission capacity in terms of switch-on and -off of resources (nodes, lines, node components) or dynamic invocation of sleep modes may result in performance degradation from reduced capacity or coverage and introduce overhead for re-activation and reconfiguration. Therefore intelligent mechanisms for network operation control have to be applied to find optimum decision in terms of timeliness and accuracy to perform the reconfigurations such that the actually provided capacity ensures as much as possible a successful transmission of user traffic demand at required quality. Degradations in user perceived service quality depend on the service specific requirements in terms of e.g. bandwidth, packet loss rate, delay and delay variations which are governed both by the kind of service (e.g. audio, video, file transfer, ...) as well as equipment and application software specific measures to cope with network performance variations. Thus for video streaming services such as IPTV countermeasures to cope with variable bandwidth and delay are implemented such as buffers to store data (see e.g ). This draft reports an approach following the considerations and requirements laid out in  to counteract the potential impact due to energy aware network operation, which is represented as bandwidth reduction, introduced stretch/delay, decreased recovery speed, additional jitter/delay variations, and other operational aspects. Issues of power-aware routing and traffic engineering have already been considered in  and  in detail. von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 3] Internet-Draft Energy Aware Control Approach for QoS July 2013 2. Conventions and Terminology 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 RFC 2119 . von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 4] Internet-Draft Energy Aware Control Approach for QoS July 2013 3. Energy aware network operation 3.1. Network model The proposed concept for load adaptive energy aware access networks follows a model similar to  where the following measures are described as primary ways to reduce energy usage o Removing redundant links from the network topology o Removing redundant network equipment from the network topology o Reducing the amount of time equipment or links are operational o Reducing the link speed or processing rate of equipment Whereas the first two actions describe permanent changes to the network the latter two are considered for dynamical adaptation of network capacity to the temporally variable traffic demand as addressed here. Considerations here shall focus on a network for fixed and mobile services such as DSL-based (digital subscriber line) fixed access as described by BBF or a cellular access network as specified by 3GPP. Technology specific approaches towards an energy aware operation are laid out e.g. in  for mobile access where some cells providing additional capacity are proposed to be switched off for reasons of power consumption optimization in case they are no longer needed. Important is that both continuity of radio coverage and service QoS remains guaranteed. A local-autonomous solution for fixed DSL networks' energy efficiency improvements is laid out e.g. in  where the data rate and the power consumption associated with it are adapted to real traffic demands observed on a particular access line by means of defined bit rate and power modes. A multi-link heterogeneous access network consisting of multiple radio access technologies (Multi-RAT) such as cellular mobile and WiFi is able to provide an end user equipment (UE) with multiple links concurrently or subsequently to enable continuous network connectivity. Depending on current load within an area of coverage (radio cell) part of the access nodes (i.e. radio base stations and WiFi access points) are temporarily switched off either completely or partially thus realizing the above mentioned measures. Similarly, a hybrid fixed-radio access network is conceivable where the specifics of the per-technology power management solutions have to be taken into account and in addition they have to be coordinated. The simplistic network model used in  is shown in Figure 1. von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 5] Internet-Draft Energy Aware Control Approach for QoS July 2013 /---R2---\ /---\ R1 R4 R5 \---R3---/ \---/ Figure 1: Simplistic model for energy aware network Corresponding to this model here the access network part is described with R1 as the UE connected to different access routers R2, R3 (or AR1, AR2) which are attached to a common aggregation node R4 (AGR) connected to the serving gateway to the core network, R5 (GW) via at least two redundant links. +-----+ +-----+ | AR1 | | GW | +-----+ +-----+ / \ / / / \ / / / \ / / / \ / / +------+ +-----+ +-----+ / | UE |______| AR2 |____| AGR |/ | | | | | | +------+ +-----+ +-----+ Figure 2: Multi-technoloy access network In Figure 2 the access routers AR1 and AR2 may provide connectivity with different characteristics due to differences in fixed and/or mobile radio technology, bandwidth, regional and temporal availability etc. 3.2. Problem description Task of the control plane to prevent ongoing sessions from negative impact of network performance variations to user perceived service quality or Quality of Experience (QoE) is to detect and counteract those variations resulting in bandwidth reduction, and additional delay and jitter. On the other hand a decreased recovery speed in case of (e.g. failure caused) loss of remaining redundant links and nodes is more a network operational issue with impact on network availability and reliability. von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 6] Internet-Draft Energy Aware Control Approach for QoS July 2013 The approach described here focusses on the well known situation that a network is dimensioned so to provide enough capacity to serve all users and services expected in so-called busy hours when multiple users are concurrently active at peak demands. During off-peak time the demanded network load is low so that part of the network in terms of access nodes and routers can be operated in sleep mode or switched off partially or completely. For a cellular network we therefore may assume that a UE is potentially being served by at least two such access nodes whereas in a fixed network customer nodes can be switched to low power mode reducing capacity and energy consumption both at the UE and in the the AR (here: DSL Access Multiplexer, DSLAM). Such a behaviour is denoted as load adaptive network reconfiguration. The concept allowing for adaptive reconfiguration is based on reliable measurement of actual traffic demand and subsequent decision on corresponding configuration actions. Therefore a data base and decision engine is employed to collect and analyse context information allowing for best decisions on changes in network topology and configuration. An optimization is achieved when provided capacity follows as much as possible the traffic demand with as little overprovisioning as possible to grant energy efficient operation and account for enough margin to cope with traffic demand uncertainties in terms of load variability to prevent perceivable quality degradations. Such quality impact may be introduced by network performance degradations in terms of congestion and bandwidth reduction in case of mismatch between capacity and demand. In addition the energy aware network operation may introduce bandwidth reduction, stretch/ delay, additional jitter/delay variations as laid out in . In a cellular system additional delay or even loss of connectivity due to handover of an UE between neighboring access nodes may occur when the currently serving node is going to energy save state. New proposals for mobility management taking into account both low handover delay and resource efficient operation are under way in WG DMM (Distributed Mobility Management) . Impact of all these parameters on different services according to their requirements have to be considered and counteracted for customer satisfaction. A communication network operating in an energy aware mode SHOULD apply additional measures to keep track of network node and link states as well as of service related network performance to minimize risk of degradations in service quality. 3.3. Solution space For energy efficient network operation with minimum power consumption at imperceptible degradation of the service quality as experienced by von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 7] Internet-Draft Energy Aware Control Approach for QoS July 2013 the user a control plane framework with data base and decision engine is required. Task of this framework is to monitor the network status (or detect changes in the network status) and track the service demand to assign the network resources (i.e. alter network topology or configuration) in such a way that both power consumption is reduced and user demands are satisfied (in terms of only minimal QoS degradations which are hardly experienced by the user). A simplified exemplary realisation of such a framework (i.e. data base DB and decision engine DE) would have to cooperate with the Network Mangement (NM) and Service Management (SM) as is specified e.g. by 3GPP in  for mobile cellular networks. Such a setting shall enable context information exchange between network elements as AR1, AR2, or AGR, GW (via signalling protocols towards NM, which are shown in Figure 3 as dotted lines) as well as user equipment UE and the DB o the framework. The abstracted context data (dashed arrows) together with other internal data (e.g. based on policies) and external (3rd party) information (not shown in Figure 3) are fed into the data base. The corresponding reconfiguration decision is made in decision entity DE considering also further data from NM and SM. Authorised commands to change the network configuration and topology are sent by NM to the network entities. + - - - - - - - - - - - - - - - + | +------+ +------+ +---+---+ +- >| DB |- ->| DE |- ->| NM&SM | + - >| | | | | | | +------+ +------+ +-------+ . . . . | . . . . . . . . | . . . . +-----+ . . +-----+ | | AR1 | . . | GW | +-----+ . . +-----+ | / .\ . / / / . \ . / / | / . \ . / / / . \ . / / | +------+ +-----+ +-----+ / + - | UE |______| AR2 |____| AGR | / | | | | | | / +------+ +-----+ +-----+ Figure 3: Exemplary deployment of energy aware control framework in network model of Figure 2 von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 8] Internet-Draft Energy Aware Control Approach for QoS July 2013 One approach is to apply a dedicated control protocol or enhance existing ones like SNMP  and NETCONF protocol  when taking into account both network status and performance. On the other hand based on a metric to assess the service performance in relation to current demand to efficiently assign the required network resources considerations as laid down in  MAY apply. Concrete measures to prevent expected performance degradations could make use of prioritization of critical sessions and corresponding de-priorisation of more robust ones based e.g. on QoS class parameters as specified by DiffServ . In case of switching on new equipment to provide additional capacity the introduced delay variation may be counteracted by providing spare capacity for those services which are highly sensitive to delay variations. In the context of mobility handling (e.g. during handover towards more energy efficient technology i.e. here between cellular and WiFi) application of DiffServ QoS attributes and corresponding parameters and mapping to technology specific figures for flows of active sessions has been proposed in . Furthermore energy related information on network devices as defined in  for network management purposes SHOULD be incorporated in a concept to control assessment of QoS requirements of different services with respect to impact of energy aware networks. Simulations and testbed implementations of load-adaptive measures to increase access network energy efficient indicate savings in the order of 30% depending on the actual topoplogy and device capabilities to support fast reliable on-/off-switching of nodes and node components (see e.g. ). von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 9] Internet-Draft Energy Aware Control Approach for QoS July 2013 4. IANA Considerations None /t.b.d. von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 10] Internet-Draft Energy Aware Control Approach for QoS July 2013 5. Security Considerations Security is an important issue in access to communication networks both in fixed-line networks and for mobile and wireless ones as described e.g. in  such that any proposed protocol must incorporate sufficiently strong protection mechanisms. Since the proposed control plane framework interoperates with the network and service management system the proper operation of which is essential for a network operator, careful examination of security issues in relation to corresponding interfaces and protocols is required. Beside that to our knowledge no new security risks are introduced with this concept. von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 11] Internet-Draft Energy Aware Control Approach for QoS July 2013 6. Acknowledgements The described concepts have been developed within research projects Com(municate) Green  and LOLA (Load Adaptive Local Area networks)  partially funded by German federal ministry of economy and technology (BMWi) under participation of DTAG T-Labs and other project partners. Contributions and valuable comments by JinHyeock Choi are gratefully acknowledged. von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 12] Internet-Draft Energy Aware Control Approach for QoS July 2013 7. References 7.1. Normative References  Bradner, S., "Key words for use in RFCs to indicate requirement levels", RFC 2119, March 1997. 7.2. Informative References  Retana, A., White, R., Paul, M., "A Framework and Requirements for Energy Aware Control Planes", draft-retana-rtgwg-eacp-01.txt, (work in progress), February 2013.  Recommendation ITU-T G.1080, "Quality of experience requirements for IPTV services", December 2008.  3GPP TR 36.927, "Evolved Universal Terrestrial Radio Access (E-UTRA); Potential solutions for energy saving for E-UTRAN (Release 11)", September 2012  Chan, H. (Ed.) et al., "Requirements of distributed mobility management", draft-ietf-dmm-requirements-05.txt, (work in progress), June 2013.  Communicate Green, Project website, available at http://www.communicate-green.de  LOLA project, available at http://www.laboratories.telekom.com/public/English/ Innovation/success-stories/Pages/Energy-efficient-ICT.aspx  Zhang, B. et al., "Power-Aware Networks (PANET): Problem Statement", draft-zhang-panet-problem-statement-02.txt, (work in progress), February 2013.  Zhang, B. et al., "Power-aware Routing and Traffic Engineering: Requirements, Approaches, and Issues", draft-zhang-greennet-01.txt, (work in progress), January 2013.  Recommendation ITU-T G.992.5, "Asymmetric digital subscriber line 2 transceivers (ADSL2) - Extended bandwidth ADSL2 (ADSL2plus)", January 2009.  Blake, S., Black, D., Carlson, M., Davies, E., Wang, Z., and W. Weiss, "An Architecture for Differentiated Services", RFC 2475, December 1998. von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 13] Internet-Draft Energy Aware Control Approach for QoS July 2013  Claise, B. et al., "Energy Management Framework", draft-ietf-eman-framework-08, (work in progress), July 2013.  3GPP TS 32.102, "Telecommunication management; Architecture (Release 11)", December 2012.  Presuhn, R., "Version 2 of the Protocol Operations for the Simple Network Management Protocol (SNMP)", STD 62, RFC 3416, December 2002.  Enns, R., Ed., Bjorklund, M., Ed., Schoenwaelder, J., Ed., and A. Bierman, Ed., "Network Configuration Protocol (NETCONF)", RFC6241, June 2011.  Clark, A., "Guidelines for Considering New Performance Metric Development", BCP170, RFC6390, October 2011.  Liebsch, M. et al., "Quality of Service Option for Proxy Mobile IPv6", draft-ietf-netext-pmip6-qos-02.txt, (work in progress), February 2013. Authors' Addresses Dirk von Hugo Telekom Innovation Laboratories Deutsche-Telekom-Allee 7 Darmstadt 64295 Germany Email: Dirk.von-Hugo@telekom.de Nico Bayer Telekom Innovation Laboratories Deutsche-Telekom-Allee 7 Darmstadt 64295 Germany Email: Nico.Bayer@telekom.de Christoph Lange Telekom Innovation Laboratories Winterfeldtstr. 21 Berlin 10781 Germany Email: Christoph.Lange@telekom.de von Hugo, Bayer, and Lange Expires January 14, 2014 [Page 14]