Internet DRAFT - draft-aranda-sf-dp-mobile
draft-aranda-sf-dp-mobile
Service Function Chaining P. A. Aranda
INTERNET-DRAFT D. Lopez
Intended Status: Informational Telefonica I+D
W. Haeffner
Vodafone
Expires: April 7, 2016 October 5, 2015
Service Function Chaining Dataplane Elements in Mobile Networks
draft-aranda-sf-dp-mobile-00
Abstract
The evolution of the network towards 5G implies a challenge for the
infrastructure. The targeted services and the full deployment of
virtualization in all segments of the network will need service
function chains that previously resided in the(local and remote)
infrastructure of the Network operators to extend to the radio access
network (RAN).
The objective of this draft is to provide a non-exhaustive but
representative list of service functions in 4G and 5G networks. We
base on the problem statement [RFC 7498] and architecture framework
[SFC-Arch] of the working group, as well on the existing mobile
networks use cases [SFC-mobile-uc] and the requirement gathering
process of different initiatives around the world [5GPPP, IMT2020,
5G-FK, IMT2020-CN ] to anticipate network elements that will be
needed in 5G networks.
Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the
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Table of Contents
1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
1.1 Terminology and abbreviations . . . . . . . . . . . . . . . 3
1.2 General scope of mobile service chains . . . . . . . . . . 3
1.3 Requirements for 5G networks . . . . . . . . . . . . . . . 4
1.4 Evolution of the end-to-end carrier network . . . . . . . . 4
2. Mobile network overview . . . . . . . . . . . . . . . . . . . . 5
2.1. Building blocks of 4G and 5G networks . . . . . . . . . . . 5
2.2. Overview of mobile service chain elements in 4G networks
and their evolution in 5G . . . . . . . . . . . . . . . . . 6
2.3 Classification schemes for 5G networks . . . . . . . . . . . 7
3 Control plane considerations . . . . . . . . . . . . . . . . . . 7
4 Operator requirements . . . . . . . . . . . . . . . . . . . . . 7
5 Security Considerations . . . . . . . . . . . . . . . . . . . . 9
6 IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 9
7 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 9
8 References . . . . . . . . . . . . . . . . . . . . . . . . . . 9
8.1 Normative References . . . . . . . . . . . . . . . . . . . 9
8.2 Informative References . . . . . . . . . . . . . . . . . . 9
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11
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1 Introduction
<Introduction Text>
1.1 Terminology and abbreviations
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].
Much of the terminology used in this document has been defined by
either the 3rd Generation Partnership Project (3GPP) or by activities
related to 5G networks like ITU-T's IMT2020. Some terms are defined
here for convenience, in addition to those found in [RFC6459].
UE User equipment like tablets or smartphones
eNB enhanced NodeB, radio access part of the LTE system
S-GW Serving Gateway, primary function is user plane mobility
P-GW Packet Gateway, actual service creation point, terminates 3GPP
mobile network, interface to Packet Data Networks (PDN)
HSS Home Subscriber Server (control plane element)
MME Mobility Management Entity (control plane element)
GTP GPRS (General Packet Radio Service) Tunnel Protocol
S-IP Source IP address
D-IP Destination IP address
IMSI The International Mobile Subscriber Identity that identifies a
mobile subscriber
(S)Gi Egress termination point of the mobile network (SGi in case of
LTE, Gi in case of UMTS/HSPA). The internal data structure of
this interface is not standardized by 3GPP
PCRF 3GPP standardized Policy and Charging Rules Function
PCEF Policy and Charging Enforcement Function
TDF Traffic Detection Function
TSSF Traffic Steering Support Function
IDS Intrusion Detection System
FW Firewall
ACL Access Control List
PEP Performance Enhancement Proxy
IMS IP Multimedia Subsystem
LI Legal Intercept
1.2 General scope of mobile service chains
Current mobile access networks terminate at a mobile service creation
point (called Packet Gateway) typically located at the edge of an
operator IP backbone. Within the mobile network, the user payload is
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encapsulated in 3GPP specific tunnels terminating eventually at the
P-GW. In many cases application-specific IP traffic is not directly
exchanged between the original mobile network, more specific the P-
GW, and an application platform, but will be forced to pass a set of
service functions. Network operators use these service functions to
differentiate their services.
In order to cope with the stringent requirements of 5G networks (cf.
Section 1.3), we expect a new architecture to appear. This
architecture will surely make extensive use of virtualisation up to
the RAN. We also expect that IP packets will need to be processed
much earlier that in the current 3GPP architecture. In this context,
it is foreseeable that Service Function Chaining will play a
substantial role when managing the chains network traffic will
traverse. We also expect new kinds of service functions specific to
the radio access part to appear and that these new service functions
will need to be managed by the SFC management infrastructure of the
operator.
1.3 Requirements for 5G networks
As set forth by the 5G-PPP [5GPPP], the evolution of the
infrastructure towards 5G should enable the following features in the
mobile environment:
o Providing 1000 times higher wireless area capacity
o Saving up to 90% of energy per service provided
o Reducing the average service creation time cycle from 90 hours to
90 minutes
o Facilitating very dense deployments of wireless communication links
to connect over 7 trillion wireless devices serving over 7 billion
people
1.4 Evolution of the end-to-end carrier network
[SFC-Mobile-UC] presents the structure of end-to-end carrier
networks and focused on the Service Function Chaining use cases for
mobile carrier networks, such as current 3GPP- based networks. We
recognise that other types of carrier networks that are currently
deployed share similarities in the structure of the access networks
and the service functions with mobile networks. The evolution towards
5G networks will make the distinction between these different types
of networks blur and eventually disappear.
5G networks are expected to massively deploy virtualisation
technologies from the radio elements to the core of the network. The
four building blocks of the RAN, i.e. i) spectrum allocation or
physical layer (PHY), i) Medium Access Control (MAC), iii) Radio Link
Control (RLC) and iv) Packet Data Convergence, are candidates for
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virtualisation.
2. Mobile network overview
[SFC-Mobile-UC] provides an overview of mobile networks up to LTE
(Long Term Evolution) networks. As the specifications mature, we will
provide the updates to the LTE architecture.
2.1. Building blocks of 4G and 5G networks
The major functional components of an LTE network are shown in Figure
2 and include user equipment (UE) like smartphones or tablets, the
LTE radio unit named enhanced NodeB (eNB), the serving gateway (S-GW)
which together with the mobility management entity (MME) takes care
of mobility and the packet gateway (P-GW), which finally terminates
the actual mobile service. These elements are described in detail in
[TS.23.401]. Other important components are the home subscriber
system (HSS), the Policy and Charging Rule Function (PCRF) and the
optional components: the Traffic Detection Function (TDF) and the
Traffic Steering Support Function (TSSF), which are described in
[TS.23.203]. The P-GW interface towards the SGi-LAN is called the
SGi-interface, which is described in [TS.29.061]. The TDF resides on
this interface. Finally, the SGi-LAN is the home of service function
chains (SFC), which are not standardized by 3GPP.
+--------------------------------------------+
| Control Plane (C) [HSS] | [OTT Appl. Platform]
| | | |
| +--------[MME] [PCRF]--+--------+ Internet
| | | | | | |
| [UE-C] -- [eNB-C] == [S-GW-C] == [P-GW-C] | | |
+=====|=========|==========|============|====+ +-----+----+-------+
| | | | | | | | | |
| [UE-U] -- [eNB-U] == [S-GW-U] == [P-GW-U]-+--+----[SGi-LAN] |
| | | | |
| | | | |
| | | [Appl. Platform] |
| | | |
| User Plane (U) | | |
+--------------------------------------------+ +------------------+
|<----------- 3GPP Mobile Network ---------->| |<-- IP Backbone ->|
Figure 2: End to end context including all major components of an LTE
network. Source [SFC-Mobile-UC]
The radio-based IP traffic between the UE and the eNB is encrypted
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according to 3GPP standards. Between the eNB, S-GW and P-GW user
plane IP packets are encapsulated in 3GPP-specific tunnels. In some
mobile carrier networks the 3GPP-specific tunnels between eNB and S-
GW are even additionally IPSec-encrypted. More precisely, IPSec
originates/ terminates at the eNB and on the other side at an IPSec-
GW often placed just in front of the S-GW. For more details see
[TS.29.281], [TS.29.274] and [TS.33.210].
In this context, service function chains will not only act on user
plane IP traffic, but also on the traffic in RAN. The way these will
act on user traffic may depend not only depend on subscriber, service
or network specific control plane metadata, but also on the state of
the network at the particular location of the user.
2.2. Overview of mobile service chain elements in 4G networks and their
evolution in 5G
[SFC-Mobile-UC] provides an overview of the service chain elements in
4G networks. Figure 3, extracted from it, shows the service chain
topology in such networks.
+------------------------------------------------------------------+
| Control Plane Environment [HSS] [MME] [PCRF] [others] |
+------------------------------------------------|-----------------+
+--------------------+
+---------------------------|--------------------|-----------------+
| User Plane Environment | | |
| | /------(S)Gi-LAN --+-----\ |
| | | | |
| | | +---[SF1]-[SF3]-[SF5]---[Appl. 1] |
| | | / | |
| [UE]---[eNB]===[S-GW]===[P-GW/TDF]--[SF2]-[SF4]-[SF6]-------+ |
| | \ | | |
| | +---[SF7]-[SF8]-[SF9]-----+ | |
| | | | | |
| \------------------------/ | | |
| | | |
+----------------------------------------------------------|--|----+
| |
OTT Internet Applications
| |
[Appl. 2] [Appl. 3]
Figure 3: Typical service chain topology.
Service Functions handle session flows between mobile user equipment
and application platforms. Control plane metadata supporting policy
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based traffic handling may be linked to individual service functions.
In 5G networks, we expect the packet gateway (P-GW) to loose its
central position and be integrated with functions in the RAN. Radio
Resource Control (RRC) in 5G network will be integrated into the
Control Plane environment.
2.3 Classification schemes for 5G networks
TBD: We expect classification schemes for 5G networks to evolve as
the standards appear.
3 Control plane considerations TBD: We except the RRC to be integrated
with the SFC Control plane in 5G.
4 Operator requirements
4G mobile operators use service function chains to enable and
optimize service delivery, offer network related customer services,
optimize network behavior or protect networks against attacks and
ensure privacy. Service function chains are essential to their
business. Without these, mobile operators are not able to deliver the
necessary and contracted Quality of Experience (QoE) or even certain
products to their customers.
As set forth by the 5G-PPP [5GPPP], the evolution of the
infrastructure towards 5G should enable the following features in the
mobile environment:
o Providing 1000 times higher wireless area capacity
o Saving up to 90% of energy per service provided
o Reducing the average service creation time cycle from 90 hours to
90 minutes
o Facilitating very dense deployments of wireless communication links
to connect over 7 trillion wireless devices serving over 7 billion
people
To meet these additional requirements, operators will need to make an
extensive use of service chains and to extend their scope to
functions in the Radio Access Network.
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5 Security Considerations
Organizational security policies must apply to ensure the integrity
of the SFC environment. SFC will very likely handle user traffic and
user specific information in greater detail than the current service
environments do today. This is reflected in the considerations of
carrying more metadata through the service chains and the control
systems of the service chains. This metadata will contain sensitive
information about the user and the environment in which the user is
situated. This will require proper considerations in the design,
implementation and operations of such environments to preserve the
privacy of the user and also the integrity of the provided metadata.
6 IANA Considerations
This document has no actions for IANA.
7 Acknowledgements
This work has been partially performed in the scope of the
SUPERFLUIDITY project, which has received funding from the European
Union's Horizon 2020 research and innovation programme under grant
agreement No.671566 (Research and Innovation Action)
8 References
8.1 Normative References
[KEYWORDS] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, DOI
10.17487/RFC2119, March 1997, <http://www.rfc-
editor.org/info/rfc2119>.
8.2 Informative References
[RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen,
T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
Partnership Project (3GPP) Evolved Packet System (EPS)",
RFC 6459, DOI 10.17487/RFC6459, January 2012,
<http://www.rfc-editor.org/info/rfc6459>.
[RFC6733] Fajardo, V., Ed., Arkko, J., Loughney, J., and G. Zorn,
Ed., "Diameter Base Protocol", RFC 6733, DOI
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10.17487/RFC6733, October 2012, <http://www.rfc-
editor.org/info/rfc6733>.
[RFC7498] Quinn, P., Ed., and T. Nadeau, Ed., "Problem Statement for
Service Function Chaining", RFC 7498, DOI
10.17487/RFC7498, April 2015, <http://www.rfc-
editor.org/info/rfc7498>.
[TS.23.003] "Numbering, addressing and identification", 3GPP TS
23.003 13.2.0, July 2015.
[TS.23.203] "Policy and charging control architecture", 3GPP TS
23.203 13.4.0, July 2015.
[TS.23.401] "General Packet Radio Service (GPRS) enhancements for
Evolved Universal Terrestrial Radio Access Network (E-
UTRAN) access", 3GPP TS 23.401 13.3.0, July 2015.
[TS.29.061] "Interworking between the Public Land Mobile
Network(PLMN) supporting packet based services and Packet
Data Networks (PDN)", 3GPP TS 29.061 13.0.0, March 2015.
[TS.29.212] "3GPP Evolved Packet System (EPS); Evolved General Packet
Radio Service (GPRS) Tunneling Protocol for Control plane
(GTPv2-C); Stage 3", 3GPP TS 29.212 13.2.0, July 2015.
[TS.29.274] "3GPP Evolved Packet System (EPS); Evolved General Packet
Radio Service (GPRS) Tunneling Protocol for Control plane
(GTPv2-C); Stage 3", 3GPP TS 29.274 12.3.0, December 2013.
[TS.29.281] "General Packet Radio System (GPRS) Tunneling
ProtocolUser Plane (GTPv1-U)", 3GPP TS 29.281 12.1.0,
January 2015.
[TS.33.210] "3G security; Network Domain Security (NDS); IP network
layer security",3GPP TS 33.210 12.2.0, December 2012
[SFC-Arch] Halpern, J. and C. Pignataro, "Service Function Chaining
(SFC) Architecture", draft-ietf-sfc-architecture-09 (work
in progress), June 2015.
[SFC-DC-UC] Kumar, S., Tufail, M., Majee, S., Captari, C., and S.
Homma, "Service Function Chaining Use Cases In Data
Centers", draft-ietf-sfc-dc-use-cases-03 (work in
progress), July 2015.
[5GPPP] The 5G Infrastructure Public Private Partnership,
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https://5g-ppp.eu
[IMT2020] ITU towards 'IMT for 2020and beyond',
http://www.itu.int/en/ITU-R/study-groups/rsg5/rwp5d/imt-
2020/Pages/default.aspx
[5G-FK] 5G Forum Korea home page, http://www.5gforum.org/#!eng/cvb1
[IMT2020-CN] IMT2020 (5G) Promotion Group China home page,
http://www.imt-2020.cn/en/introduction
Authors' Addresses
Pedro A. Aranda Gutierrez
Telefonica I+D
Zurbaran, 12
Madrid 28010
ES
Phone: +34 913 129 566
Email: pedroa.aranda@telefonica.com
Diego R. Lopez
Telefonica I+D
Zurbaran, 12
Madrid 28010
ES
Phone: +34 913 129 041
Email: diego@tid.es
Walter Haeffner
Vodafone
Vodafone D2 GmbH
Ferdinand-Braun-Platz 1
Duesseldorf 40549
DE
Phone: +49 (0)172 663 7184
Email: walter.haeffner@vodafone.com
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