France Telecom - Orange confidential

New Control Plane in 3GPP LTE/EPC Architecture for

On-Demand Connectivity Service

Siwar BEN HADJ SAID¹, Malla Reddy SAMA¹, Karine GUILLOUARD¹, Lucian SUCIU¹,

Gwendal SIMON², Xavier LAGRANGE² and Jean Marie BONNIN²

¹Orange Labs, France ²Télécom Bretagne, France

IEEE CloudNet’13

San Francisco, USA

11-13 Nov 2013

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Outline

I. Introduction & Background

II. OF-Based LTE/EPC Architecture

I. Architecture Description

II. Data Plane Establishment Procedure

III. On-Demand Connectivity Service

I. Resiliency

II. Load Balancing

IV. Implementation Challenges

V. Conclusion & perspectives

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Introduction

Mobile data traffic has

been growing at an

unprecedented rate over

the last few years.

Huge data traffic increase

and may cause signaling

storms in the network.

– Smartphones and

tablets generate 40% of

the data traffic and 99%

of the signaling traffic.

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LTE/EPC Architecture

External Packet

Data Networks

eNBUE

S1(GTP-U) S5 (GTP-U) SGi

S1

(S1-

AP)

S11 (G

TP

-C)

S6a (Diameter)

S5 (GTP-C)

Control Plane

User Plane

Evolved Packet Core

(EPC)E-UTRAN

MME HSS

SGW-D

SGW-C

PGW-D

PGW-C

eNB

The LTE/EPC has been designed to support only packet based

services.

The EPC has a flat, all-IP architecture with separation of control plane

and data plane.

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LTE/EPC Drawbacks

The initial attachments lead to a systematic establishment of the data

plane, even when there is no data traffic to be sent.

The data plane establishment procedure is unaware of the session

type.

The TEID values are locally allocated by each node new TEID

values should be exchanged for each node relocation.

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LTE/EPC Drawbacks - 2

SGW could be a bottle neck for possible user traffic congestion.

Network equipment failure.

This PGW can be

any where in all

over the world

Home

PDN

PGW

SGW

Internet

(Ex. SIPTO above RAN)

PGW IMS Semi-distributed

GW (SGi)

PGW

This PGW could be allocated per

county or region.

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OF-Based LTE/EPC Architecture

Separation of control and

data plane from SGW.

Replacing S1-MME and S11

interfaces with OF.

SGW-D represents an

advanced OF switch that is

able to en/decapsulate GTP

packets.

Unique TEID values per

session.

eNB keeps the same radio

functions.

eNB

eNB

OpenFlow Controller

MME SGW-C

S5 (G

TP-C

)OpenFlow

protocol

UE

S1(GTP-U)

S5 (GTP-U)

SGW-D

PGW-D

PGW-C

API

SGW-D

SGW-D

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On-Demand Connectivity Service

- Resiliency

- Load Balancing

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Resiliency – 3GPP LTE/EPC case

The 3GPP restoration procedure related to the SGW failure is not

transparent as it cuts off active sessions.

Session re-establishment of impacted users may generate

significant amount of signaling.

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Resiliency – OF-Based LTE/EPC case

Easily manage the active sessions during any SGW-D failures.

Less packet loss.

Centralized the TEID allocation function.

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Load Balancing – 3GPP LTE/EPC case

SGW and PGW selection is performed by the MME.

Offline weight factors in DNS server.

Proactive load balancing.

SGW could be a bottle neck for possible user traffic congestion.

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Load Balancing – OF-Based LTE/EPC case

Real time load statistics.

Free the overloaded SGW by moving some sessions seamlessly to

another SGW in the same domain.

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Implementation Challenges

SGW control and data plane separation.

Building mobile network based OF controller.

The OF protocol should be extended to transport the UE-MME

exchanges transparently, e.g.

– Authentication messages

– Mobility messages

Shifting all control plane entities into cloud platform.

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Conclusion & Perspectives

Proposal: OpenFlow-based control plane for LTE/EPC

architecture

– The SGW control plane is separated from the data forwarding plane

– The SGW control plane is centralized and uses the OpenFlow protocol to

remotely manage the SGW data forwarding plane

The proposed architecture ensures the on-demand connectivity service

even in critic situation such as network equipment failure and overload

situations

Perspectives:

– Realize a testbed to validate the resiliency and load balancing aspects in our

proposal

– Try to make standardize the OF-based LTE/EPC in ONF working groups.

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