MPTCP Working Group L. Deng INTERNET-DRAFT D. Liu Intended Status: Informational T. Sun Expires: August 14, 2014 China Mobile February 14, 2014 MPTCP Proxy for Mobile Networks draft-deng-mptcp-mobile-network-proxy-00 Abstract This document discusses the motivation and usecases for ISP deployed MPTCP proxies in mobile networks. Status of this Memo This Internet-Draft is submitted to IETF 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." The list of current Internet-Drafts can be accessed at http://www.ietf.org/1id-abstracts.html The list of Internet-Draft Shadow Directories can be accessed at http://www.ietf.org/shadow.html 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 Expires August 6, 2014 [Page 1] INTERNET DRAFT February 7, 2014 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 . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3 Considerations for MPTCP Proxy . . . . . . . . . . . . . . . . . 3 4 Use-cases for Network deployed MPTCP Proxy . . . . . . . . . . . 4 4.1 Dynamic traffic offloading based on network information . . 4 4.2 Resource pooling for reduced expense . . . . . . . . . . . . 4 5 Requirements for MPTCP Proxy . . . . . . . . . . . . . . . . . 5 5.1 Protocol transition . . . . . . . . . . . . . . . . . . . . 5 5.2 Traffic mediation . . . . . . . . . . . . . . . . . . . . . 5 5 Security Considerations . . . . . . . . . . . . . . . . . . . . 5 6 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 7 References . . . . . . . . . . . . . . . . . . . . . . . . . . 7 7.1 Normative References . . . . . . . . . . . . . . . . . . . 7 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 8 Expires August 6, 2014 [Page 2] INTERNET DRAFT February 7, 2014 1 Introduction Due the scarcity of wireless frequency resources and the instability of wireless signals, combined with the operators' strong motive to preserve service upgrade with smooth network evolution, make full use of mobile terminal's multi-homing capability has long been a quest for mobile networks. In particular, the motivations include resource pooling for better performance (where the network could provide a better performance for resource-intensive services by allowing them to transparently using combined capacities from different RATs) as well as intelligent selection for better accommodation and seamless handover for better mobility. Since R6, 3GPP network defined GAN, interfaces for non-3GPP RATs through GERAN simulation. In R7, I-WLAN was introduced to 3GPP network, for inter-working of PLMN with WLAN RAT. In R8, it is specified that a shared anchor could be used for both I-WLAN and PS RATs, yielding seamless handover. Since R8, there have been work on EPS's mobility support for simultaneous multiple RATs through different PDN connections (MAPCON). Most recently, in R10, it is possible to use EPS's mobility support for simultaneous multiple RATs through a single PDN connection (IFOM). However, there is still not possible for a single IP flow to make full use of multiple interfaces simultaneously. 2 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 [RFC2119]. 3 Considerations for MPTCP Proxy MPTCP[RFC6824] offers transparent wireless resource pooling for a single "IP flow" for multi-homing UEs with least network complications, as it effectively implements automatic RAT selection/handover/pooling through TCP's adaptive end-to-end rating mechanism[RFC6356]. However, end-to-end MPTCP solution deprives network's control over service/RAT preference, which is considered to be essential for better operation and service provision in 3GPP networks. As the same time, it has to suffer from compatibility issues with legacy application SPs who are reluctant to support MPTCP natively. Expires August 6, 2014 [Page 3] INTERNET DRAFT February 7, 2014 Therefore, network deployed MPTCP proxy comes as a compromise, which would certainly benefit MPTCP-enabled UEs without SP's MPTCP deployment by providing protocol adaptation, and at the same time maintain as the wireless network operator's policy enforcement point for their preferred network selection/usage strategies. 4 Use-cases for Network deployed MPTCP Proxy For 3rd party service provider who does not supporting MPTCP in their servers, the network deployed proxy could be used to enable MPTCP capability in resource pooling from various radio access networks for enhanced QoE/mobility. As for 3rd party service providers supporting MPTCP, the network deployed proxy could also bring benefits to both the operator and the users by enabling the following benefits. 4.1 Dynamic traffic offloading based on network information For real-time interactive services with higher QoS requirements it is expected that 3GPP network can provide better guarantees on the average case. For bulk data transfer who is satisfied with best- effort delivery, Wi-Fi would be a great choice. But the vertical partition does not fit everywhere for the wireless condition itself is quite dynamic and hard to predict. It is important to implement adaptive offloading mechanisms in order to achieve higher resource utility with ever changing radio environment for a possibly moving terminal based on network status, e.g. cell load, AP's signal intensity, user's subscription type, etc. 4.2 Resource pooling for reduced expense Due to its low construction and operation expenses, Wi-Fi has been adopted by mobile operators as a complementary RAT for their traditional 3GPP networks. However, different construction and operation expenses of various radio networks result in differences in charging rates/policies for different RATs. For instance, Wi-Fi access may be charged by the access duration, while the 3GPP access may be charged by the consumed data volume. Even if using the same policy, Wi-Fi service is expected to be much cheaper than 3GPP data service. Moreover, different subscription packages may offer various data plans for various RATs. For instance, a basic 4G package may contain free data volume as well free Wi-Fi access too. Expires August 6, 2014 [Page 4] INTERNET DRAFT February 7, 2014 By enabling MPTCP session between UE and network proxy, via mediating sub-flow data traffic based on their Radio access types and the user's subscription package, it is possible to further reduce the usage expenses from both sides of the network and user. 5 Requirements for MPTCP Proxy In order to realize the above use-cases, it is expected that a network deployed MPTCP proxy provide the following functionality: 5.1 Protocol transition To allow a MPCTP-enabled UE to make full use of the multiple radio interfaces even if it is communicating with a non-MPTCP server, the proxy should support (a) Detection of UE's MPTCP capability; (b) Negotiation with MPTCP UE on behalf of non-MPTCP SP; (c) Translation/Mapping between TCP and MPTCP sessions. 5.2 Traffic mediation (a) Anchoring of sub-flow traffic: On one hand, it is not always possible for a single GW be sitting on the path of every sub-flow from a MPTCP session, hence explicit traffic anchoring to enable a single point of general control over MPTCP sub-flows should be considered. (b) Mediation of sub-flow traffic: On the other hand, for fine- grained mediation of sub-flow traffic, both static and dynamic selection/offloading/pooling policies should be allowed. For instance, "always prefer Wi-Fi over 3GPP" could be a static policy for bulk data transfer services, while "use 3GPP only for backup unless Wi-Fi is congested" could be a dynamic offloading policy for a un-prioritized VoIP service. 5 Security Considerations TBA. 6 IANA Considerations There is no IANA action in this document. Expires August 6, 2014 [Page 5] INTERNET DRAFT February 7, 2014 Expires August 6, 2014 [Page 6] INTERNET DRAFT February 7, 2014 7 References 7.1 Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3550] Schulzrinne, H., Casner, S., Frederick, R., and V. Jacobson, "RTP: A Transport Protocol for Real-Time Applications", STD 64, RFC 3550, July 2003. [RFC3611] Friedman, T., Ed., Caceres, R., Ed., and A. Clark, Ed., "RTP Control Protocol Extended Reports (RTCP XR)", RFC 3611, November 2003. [IFOM] IP Flow Mobility and seamless WLAN offload. 3GPP work item 450041. [RFC6824] Ford, A., Raiciu, C., Handley, M., and O. Bonaventure, "TCP Extensions for Multipath Operation with Multiple Addresses", RFC 6824, January 2013. [RFC6356] Raiciu, C., Handley, M., and D. Wischik , "Coupled Congestion Control for Multipath Transport Protocols", RFC 6356, October 2011. Expires August 6, 2014 [Page 7] INTERNET DRAFT February 7, 2014 Authors' Addresses Lingli Deng China Mobile Email: Email: denglingli@chinamobile.com Dapeng Liu China Mobile Email: Email: liudapeng@chinamobile.com Tao Sun China Mobile Email: Email: suntao@chinamobile.com Expires August 6, 2014 [Page 8]