ISCC’16: The 21st IEEE Symposium on Computers and ...luciano/publications/iscc16-pres.pdfrate of...

ISCC’16: The 21st IEEE Symposium on Computers and Communications

OpenFlow-based Mechanisms for QoS in LTE Backhaul Networks

Luciano Jerez Chaves1,2Islene Calciolari Garcia2

Edmundo R. Mauro Madeira2

1Federal University of Juiz de Fora (UFJF), Brazil2University of Campinas (Unicamp), Brazil

ISCC’16: The 21st IEEE Symposium on Computers and CommunicationsJune, 2016

Outline

❖ Introduction

❖ Software-Defined Networking

❖ Long-Term Evolution networks

❖ SDN and LTE integration

❖ Proposed QoS mechanisms

❖ Conclusions and future work

2


Introduction

3

❖ Mobile data traffic is increasing at a compound annual growth rate of 57%

❖ Increasing number of higher-generation connectivity

❖ Multimedia streaming represents more than 50% of mobile data traffic

Exabytes per month

[1] “Cisco visual networking index: Global mobile data traffic forecast update, 2014-2019”, White Paper, Cisco, Feb, 2015.


Future networks

4

❖ 5G networks for people and things

❖ Lower latency and higher data rates

❖ Heterogeneous Networks (HetNets)

❖ High-connectivity backhaul and core networks for more base stations

Software-Defined Networking will be a key differentiator of 5G systems


Contributions

❖ This work contributes with…

❖ OpenFlow protocol integrated into LTE backhaul networks

❖ Specialized OpenFlow EPC controller for LTE traffic control

❖ Network traffic routing

❖ Bearer admission control

❖ LTE QoS realization

5


Software-Defined Networking

6

❖ Decouples the control plane from the data plane

❖ Network intelligence is centralized in software

❖ Simplified distributed forwarding hardware

❖ More agile and cost-effective networks


OpenFlow protocol

7

❖ SDN southbound interface

❖ Basic primitives to program the forwarding plane of OpenFlow switches

❖ Concepts of flows to identify network traffic

❖ Switch datapath specification


Long-Term Evolution networks

❖ 4G standard for high-speed wireless communication

❖ Maintained by the 3rd Generation Partnership Project

❖ Evolved Packet System (EPS)

• Evolved Universal Terrestrial Radio Access Network (E-UTRAN)

• Evolved Packet Core (EPC)

8


eNB S-GW P-GWUE Internet

End to End service

Radio bearer S1 bearer

S5/S8 bearerE-RAB bearer

EPS bearer External bearer

LTE-Uu S1-U S5/S8 SGi

E-UTRAN EPC

MME HSS PCRF

S1-MME

S6a

S11 GxGx

Control plane

Data plane

EPS architecture Packet domain onlyStandardized interfacesGPRS Tunneling Protocol (GTP)

9


LTE QoS and EPS bearers

10

❖ EPS bearers identify packet flows with common QoS treatment

❖ Bearers are associated with a QoS Class Identifier (QCI)

❖ Minimum Guaranteed Bit Rate (GBR)

❖ Non-Guaranteed Bit Rate (Non-GBR)


SDN and LTE integration

❖ Proposed integration

❖ OpenFlow switches in the backhaul network (S1 interfaces)

❖ New OpenFlow match fields for GTP TEID routing

❖ No changes in EPC elements for tunnel handling

11


Network topology❖ Wired backhaul topology

❖ Ring with arbitrary number of OpenFlow switches

❖ Unified S-GW/P-GW gateway element

❖ Ethernet full-duplex links

❖ Wireless access topology

❖ Hexagonal grid with inter-site distance of 500 m

❖ UEs scattered closed to the eNBs

12

OpenFlowswitch

OpenFlow Ring

Controller

P-GWS-GW

eNB

UE

InternetMME

PCRF


OpenFlow EPC controller

13

❖ LTE traffic control mechanisms

❖ Network traffic routing



❖ Controller communicates with the MME element for bearer management procedures

MME

Cont

rol la

yer

Appl

icatio

n la

yer

OpenFlow EPC Controller- Traffic routing- Bearer admission control- LTE QoS realization

Internet

Infra

stru

ctur

e la

yer


Network traffic routing

❖ Look for routing paths and install GTP TEID match rules

❖ For the ring topology, the routing options are reduced to clockwise or counter-clockwise paths

❖ Different routing policies

❖ Shortest Path Only

❖ Shortest Path First

14


Bearer admission control

❖ Reserve the requested bandwidth for accepted GBR bearers

❖ Shortest path only routing policy blocks GBR requests when there is no available bandwidth in the shortest routing path

❖ Shortest path first routing policy checks on the other routing path for the required bandwidth before blocking the GBR request

15


LTE QoS realization❖ Translate from bearer-level QoS (QCI) to transport-level QoS

❖ LTE is IP-based, so it can leverage DiffServ to provide QoS

❖ OpenFlow match the DiffServ Code Point (DSCP) header filed

❖ OpenFlow meters are used for GBR/Non-GBR traffic coexistence

❖ Limit the GBR bearer throughput to the maximum bitrate

❖ Limit the aggregated Non-GBR throughput over each link

❖ Dedicated output queue for VoIP traffic improvement

16


Performance evaluation

17

Traffic applications Traffic type Bearer QCI

VoIP UDP GBR (1)

Live Video Streaming UDP GBR (2)

Buffered Video Streaming TCP Non-GBR (6)

Live Video Streaming UDP Non-GBR (7)

HTTP TCP Non-GBR (8)

❖ Network Simulator 3 + OFSwitch13 module

❖ Backhaul ring size: 4/10 OpenFlow switches connected to eNBs

❖ UE load distributions: balanced or unbalanced (30% of UEs in one half of the ring, 70% on the other half)

❖ Admission control: up to 40% of link bandwidth for GBR traffic


Traffic routing and admission control

4 OpenFlow switches in the ringUnbalanced load configuration

Improved block ratio for the shortest path first routing policy

18

0

20

40

60

80

100

1 2 3 4 1 2 3 4

Rout

ing

dist

ribut

ion

(%)

Shortest Blocked Inverted

Shortest Path FirstShortest Path Only 0

5

10

15

20

50 100 150 200 250 300 350 400 450

Bloc

k ra

tio (%

)

Number of UEs

Shortest Path OnlyShortest Path First

Average block ratio Traffic routing distribution


LTE QoS realization (GBR/Non-GBR coexistence)

10 OpenFlow switches in the ringBalanced load configurationShortest path first routing policy

GBR throughput without Non-GBR interference

19

0

20

40

60

80

100

120

100 140 180 220 260 300 340 380

Band

widt

h (M

bps)

Number of UEs

Non-GBR tra cGBR tra c

GBR reserved

Traffic throughput and GBR reserved bandwidth

0

10

20

30

40

100 140 180 220 260 300 340 380

Pack

et d

rop

(%)

Number of UEs

Non-GBR tra cGBR tra c

Packet drop ratio by OpenFlow meters


LTE QoS realization (VoIP improvements)

10 OpenFlow switches in the ringBalanced load configurationShortest path first routing policy

VoIP mapped onto high-priority output queues

20

0

1

2

3

4

5

100 140 180 220 260 300 340 380

VoIP

ave

rage

jitte

r (m

s)

Number of UEs

Coex. OFFCoex. ON

VoIP queues

0

1

2

3

4

5

100 140 180 220 260 300 340 380

VoIP

ave

rage

del

ay (m

s)

Number of UEs

Coex. OFFCoex. ON

VoIP queues

VoIP delay comparison VoIP jitter comparison


Conclusions and future work❖ This paper shows…

❖ How the OpenFlow protocol can be used to assist LTE traffic control management

❖ Backhaul traffic routing



❖ As future work…

❖ Improve the proposed mechanisms to support UE mobility

21

ISCC’16: The 21st IEEE Symposium on Computers and CommunicationsJune, 2016 22

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