Internet DRAFT - draft-deng-mptcp-mobile-network-proxy
draft-deng-mptcp-mobile-network-proxy
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.
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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
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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.
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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.
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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.
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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.
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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
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