First Demonstration of Software Defined Networking (SDN) over Space
Division Multiplexing (SDM) Optical Networks
N. Amaya(1) , S. Yan(1) , M. Channegowda(1) , B. R. Rofoee(1) , Y. Shu(1) , M. Rashidi(1) , Y. Ou(1) , G. Zervas(1) ,R. Nejabati(1) , D. Simeonidou(1) ,(2)(2)
B.J. Puttnam , W. Klaus , J. Sakaguchi(2) , T. Miyazawa(2) , Y. Awaji(2) , H. Harai(2) , N. Wada(2)(1)(2)

High-Performance Networks Group, University of Bristol, United Kingdom B norberto.amaya@bristol.ac.uk
National Institute of Information and Communications Technology (NICT), Tokyo, Japan

Abstract We demonstrate for the first time a fully integrated SDN-controlled bandwidth-flexible and programmable
SDM optical network utilising sliceable self-homodyne spatial superchannels to support dynamic bandwidth andQoT provisioning, infrastructure slicing and isolation.
Introduction
Space Division Multiplexing (SDM) has been shown toprovide dramatic increases in transmission capacity 1,2 .
Also, spatial superchannels 3 and Self-Homodyne Detection (SHD) have been proposed to relax the receivercomplexity and laser linewidth requirements by exploiting the highly correlated properties of different coresin a Multi-core Fibre (MCF) 4,5 . Recent work has also
explored the benefits of SDM to support new networking functionalities beyond the straightforward increasein capacity, i.e. to provide additional flexibility in bandwidth provisioning 6 . However, it is becoming apparent
that, to fully exploit SDM networking, it is necessary todevelop novel approaches in network control and management, able to support the increased complexity ofthe transport layer while facilitating new network functionalities enabled by the additional spatial dimension.
For example, SDM makes it possible to create multiple
isolated slices of the optical infrastructure by leveraging
low levels of crosstalk among channels using different
spatial resources. Optical network slices could be allocated, controlled or even programmed by different network services, facilitating emerging requirements for ef-…"Network Service1
Webservice Interface

ficient and dynamic infrastructure sharing. Here, for the
first time, we propose to utilize Software Defined Networking (SDN) for control and management of novel
bandwidth-flexible and programmable SDM networks.
This enables service level programmability of networkand transport functions by abstracting the technological details of the SDM infrastructure, making it sliceable, directly accessible and controllable by network
services.
In this paper, we present the first demonstration ofSDN-enabled control plane, fully controlling the nodearchitecture configuration and bandwidth provisioning,over an SDM network that consists of three Architecture on Demand (AoD) nodes, linked by two MCFs with19 and 7 cores, carrying sliceable self-homodyne spatial superchannels. Such superchannels support multiple bit rates by varying the number of aggregated spatial subcarriers and their modulation format. Idle subcarriers are used for transmission to other destinations
by means of superchannel slicing. AoD nodes dynamically implement node architectures tailored to traffic requirements, i.e. flexible technology. Novel SDM Flow-…"Network Service N

Application Northbound Interface

Webservice Interface

Multi-dimensional Slicing

SDN Controller

SDM Flow Mapper

Topology Discovery and DB

Flow Monitoring

OpenFlow (OF) Interface
Optical Flow

DEMUX

DEMUX

PT1 path

Tx-1 64G QPSK or 128G 16QAM

Node-13 8 12 17
1 5 10 15 19
2 7 13 18
6 9 1435200µmµm

dropdropSSS

12391214..
.

OF Agent

CoreSSS

14x128G
16QAM

12391214

MUX

16QAM

5781011Cross-connections
11SDM
2 MUX DEMUX 23344..
5.
614
MCF-1
7.
1519-core.
16 fibre (10 km) . ..
18 .
171918 A
4 11 1619SP SP

SPSwitch
5781011SP

QPSK

14x64G
QPSK

Fibre

CFSDM

120G

OF Agent

Node-3fibre (30 km)

Node-2Tx-3 QPSKMF

1 MUX DEMUX 122334455MCF-26677-core
7B

PT3 path

BW

Drop ports

DFBsSPTx-240G BPSKOF Agent

12344 x Single Mode FibresSPOF AgentOF Ag ent

197µm

26437556µm

Fig. 1: Experimental setup of the SDN-controlled SDM network. Abbreviations: 16QAM: 16QAM emulator; BW: Bandwidth; CF:Centre Frequency; DFBs: DFB laser bank; MF: Modulation Format; QPSK: QPSK modulator; SP:splitter.

mapper and multi-dimensional bandwidth slicing service successfully map network application requirements, i.e. bandwidth and Quality of Transport (QoT),
to the spatial superchannel slices and the switching
technology available in the AoD nodes.
Experimental SDM network data plane setup
The experimental setup is comprised of three transmitters (two of them support self-homodyne transmission) and three programmable nodes, as shownin Fig. 1. Node 1 and 2 were connected by a 10km 19-core fibre (MCF-1) with an average intercore
crosstalk of -37.2 dB. Nodes 2 and 3 were connectedby a 30-km 7-core fibre (MCF-2) with an average intercore crosstalk of -54 dB. Insets A and B of Fig. 1
show the MCF facets. The average total loss of theMCF including SDM MUX/DEMUX was measured tobe 5.2 dB and 9.8 dB for MCF-1 and MCF-2, respectively. Also, four independent Single Mode Fibre (SMF)
links directly interconnect Nodes 1 and 3. Tx-1 generates sliceable self-homodyne spatial superchannels
over 14 wavelengths. Each spatial superchannel consists of a programmable number of spatial subcarriers(from 1 to 18) with 64-Gb/s single-polarisation QPSKor 128-Gb/s 16QAM modulation and a Pilot Tone (PT),Self-homodyne spatial superchannels
provisioned from Node-1 to Node-2

PT11558.98 64G 64G 64G 64G 64G 64G 64G 64G

PT1(b) Slice 2: 512G (8x64G QPSK) self-homodyne spatial superchannel
Source: Node-1, Destination: Node-2, Bit rate: 512 Gb/s, BER: <1e-5
16QAM spatial subcarriers on
Shared Pilot
Wavelength
MCF-1 cores 15-18
Tone in core 19

1558.98

128G 128G 128G 128G

PT1(c) Slice 3: 512G (4x128G 16QAM) self-homodyne spatial superchannel
Source: Node-1, Destination: Node-2, Bit rate: 512 Gb/s, BER: <2e-3Core7128G 128G 128G 128G PT1 40G 40G128G 128G 128G 128G PT1 40G 40G128G 128G 128G 128G PT1 40G 40G
PT164G 64G 64G 64G PT1PT164G 64G 64G 64G PT164G 64G 64G 64G PT1128G 128G 128G 128G PT1 40G 40G
64G 64G 64G 64G PT164G 64G 64G 64G PT1 40G 40G128G 128G 128G 128G PT1 40G 40G
PT1128G 128G 128G 128G PT1 40G 40GCore664G64G64G64G64G64G64G64G64G64G64G64G64G64GCore564G64G64G
64G
64G
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Core4

64G
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Core3

Core15

64G
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Core2

Core14

64G
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40G 40G 64G 64G
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40G 40G 64G 64G64G 64G
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40G 40G 64G 64G64G 64G
40G 40G 64G 64G
40G 40G 64G 64G64G 64G
40G 40G 64G 64G

64G
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64G64G64G64G64G
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64G
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64G64G64G
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64G64G64G64G64G64G64G64G64G
20G
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64G20G
64G64G20G
64G64G64G64GPT3PT3PT3PT3PT364GPT364G64GPT364G

PT1PT1PT1PT1PT1PT1
PT1PT1PT1PT1
PT1
PT1
PT1
PT1128G 64G 64G 64G 128G 128G from
Slice 3 at
-20 128G 128G 64G 128G 64G
1558.98nm

Core1

Core1364G64G
64G64G
64G64G
64G
64G64G
64G64G64G
64G64G

MCF32#73core#Fibre#(30km)
SMF4

Core1264G64G
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SMF2

Core1164G
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SMF1

Core1064G
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1558.98 64G 64G 64G 64G 64G 64G

Core19

Core964G
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(a) Slice 1: 384G (6x64G QPSK) self-homodyne spatial superchannel.
Source: Node-1, Destination: Node-3, Bit rate: 384 Gb/s, BER: <1e-5.
Shared PT
QPSK spatial subcarriers on
Wavelength
in core 19
different cores

Core18

Core864G
64G
64G
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Shared PT
in core 19

Core17

Core764G
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QPSK spatial subcarriers on
different cores

Core16

Core6

64G
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Intensity (dBm)

Core5

20G
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Core420G
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Core340G

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SMFs

64G
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64GSelf-homodyne 20G channels
from Node-2 to Node-3
128G-40

64G MCF2
Core 51558.98nm

-60
1540

1545

1550

1555

1560

Wavelength (nm)(d) Signals transmitter over MCF-1 core 17.
128G
Slice 1-log(BER)

Wavelength

40G
40G
40G

MCF31#193core#Fibre#(10km)

Self-homodyne spatial superchannels
from Node-1 to Node-3

Core1

128G
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Tx*3

64G
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Tx*2

λ
1539.771541.35
1542.941543.731544.531545.32
1546.121547.721549.32
1550.92
1552.52
1554.131556.55
1558.98

Tx*1,
16QAM

12
3
45678910111213
14

Tx*1,QPSKChannelTx#(Sub)carrier#Bitrate

40G BPSK channels fromNode-1 to Node-3

SMF3

Self-homodyne spatial superchannels
provisioned from Node-1 to Node-3

all at the same wavelength but using different cores, as
shown in Fig. 2(a). Tx-1 is connected to Node-1 and isused by the SDN control plane for provisioning flexiblebandwidth channels towards Node-2 or Node-3. Tx2, connected to Node-1, generates Binary Phase Shift
Keying (BPSK)-modulated 40-Gb/s channels. Tx-3,connected to Node-2, generates seven self-homodyne
channels with 20-Gb/s QPSK modulation. PTs generated at Tx-1 and Tx-3 are labeled PT1 and PT3 respectively, and are required to demodulate the QPSK
and 16QAM signals, as they are generated from DFBs
with large linewidths. To retain their correlation, themodulated spatial subcarriers and their corresponding PT are generated, added to the nodes, transmitted (through the same MCFs), and dropped together.
Nodes 1-3 implement the AoD concept 6 and consist of
an optical backplane that interconnects MCF/SMF fibre inputs, modules (e.g. Spectrum Selective Switch(SSS), Erbium-Doped Fibre Amplifiers (EDFAs), etc.)
and MCF/SMF fibre outputs, as shown in Fig. 1. The
architecture implemented by AoD is calculated and implemented automatically by the SDN control plane byconfiguring cross-connections in the optical backplane.

345
664G-Node2-MCF1(10)64G-Node3-drop
Slice 2
Slice 3
16QAMQPSK2(e) BER.

440G SMF120G(1556.55nm)

QoT Decision Threshold

6810
Channel Number

1214(f) Signal constellations.

Fig. 2: Channels provisioned in the experimental demonstration.

Experimental SDN control plane setup
The proposed control plane architecture includes anSDN controller and a multi-dimensional network slicing
service, as shown in Fig. 1. The Open Flow (OF) interface in the controller and the OF Agent in the device utilize an extended OF protocol to abstract the transmitter
states (Tx-1, Tx-2 and Tx-3), the AoD nodes’ modulesand features, network topology and connectivity (SMFsand MCFs). The abstraction method handles MCFs asa single entity with multiple spatial channels, so that
this information is available for routing self-homodynechannels. SMFs are abstracted as multiple entities witha single spatial channel each. Here, we propose a new
multi-dimensional Optical Flow, as shown in Fig. 1,supporting SDM and multiple transport formats. We
have extended the switch-features message of standard OF protocol for enabling the controller to discover underlying physical layer devices, their capabilityand their connectivity and store them in the Topology
Database. This information is exposed through the Application Northbound Interface as an abstracted topology, comprising a set of generic nodes and links. Eachnode is characterized by its switching and programming
capability, and each link by its supported bandwidth,

granularity and QoT. We have also developed the novel
multi-dimensional network slicing service shown in Fig.
1. It runs a heuristic optimisation algorithm to map
user/application bandwidth slice requests to the viewof the network provided by the SDN controller. In conjunction with the Flow Mapper, it translates connectivity
requirements, i.e. source, destination, bandwidth andQoT, into physical layer requirements, i.e. fibre (SMFor MCF), core(s), wavelength and modulation format.
The SDN controller configures the physical layer resources, i.e. transmitters and AoD nodes, according
to the output of the Flow Mapper using the extended
OF Flow-Mod messages.

Topology
discoverymessages

OF Agent acknowledgement + device
processing

Slicing service request
via webservice

AHTTP ASCII
code

Topology Discovery Time (1)Multi-dimensional Slicing (2)Controller <-> OF Agent ACK (3)Device Processing (4)Results
To test the proposed SDN-controlled SDM network, we
designed and implemented a network application thatgenerates requests simulating users/applications withdifferent bandwidth and QoT (BER) requirements anddifferent source and destination pair. Fig. 2 shows
the channels switched through the network. All selfhomodyne spatial superchannels are switched throughMCFs, whereas 40G BPSK channels are switchedthrough SMFs, as they do not require SHD. We demonstrate flexible bandwidth provisioning (384G, 512G and512G) with different QoT requirements (BER<1e-5,BER<1e-5 and BER<2e-3 respectively) using threeslices of the self-homodyne spatial superchannel transmitter at 1558.98 nm, as shown in Figs. 2 (a), (b) and(c). Spatial superchannel slices are successfully provisioned by the SDN control plane, which configures Tx-1
(e.g. to select 16QAM for Slice-3), calculates and configures the signal and PT paths through the SDM network (e.g. fibre, core and wavelength selection, AoD
cross-connections and SSS pass-bands). In order toreduce crosstalk on the shared WDM PTs, the algorithm routes PT1 through core 19, which is one of theexternal cores of MCF-1. Similarly, at Node-2, one copyof PT1 is dropped for SHD of the dropped channels,
while another is transmitted over MCF-2 core 7. PT3 istransmitted over MCF-2 core 6, after WDM multiplexing
with 64-Gb/s signals from Tx-1.
The signalling exchange between the OF Agent, theSDN Controller and the multi-dimensional slicing service, used to setup Slice-1 (Fig. 2(a)) is shown in Fig.
3. It shows the OF Topology Discovery features messages followed by the bandwidth request sent to theslicing service solver via the controller. The HTTP webservice request shows the ASCII code with the XML
details sent to the slicing service i.e. 384 Gb/s withBER<1e-5 from Node-1 to Node-3. Once the slicing
service finds the best solution, the flow mapper issues
the corresponding Flow Mod messages. This is verified by receiving the port status update from the Agent.
Inset A in Fig.3 plots the average path setup times for
Slice-1. The slicing service and the device configuration times contribute most of the setup delay, due to thecomplexity associated with the request and the implementation of the OF abstraction using the device’s pro-0246Path Setup Time [sec]Fig. 3: Wireshark traces showing openflow features message,
multi-dimensional slicing webservice request and flow modification messages with acknowledgement. Inset: End-to-Endcontrol plane path setup times.

prietary programming interface. These results demonstrate that an OF-based SDN solution provides a simple and reliable interface to abstract the SDM network,
so intelligent network services can run seamlessly overthe controller. Fig. 2(d) shows the signals on MCF-1
core 17, after provisioning Slice 3. SHD 4 followed byoff-line analysis was used to measure the BER of thespatial superchannels. Results are presented in Fig.
2(e). The measured end-to-end BER for 16QAM andQPSK spatial subcarriers was below 2e-3 and 6e-6 respectively. 40G BPSK was measured error-free.
Conclusions
We have presented the first SDN over SDM multigranular switching network based on two MCFs,
with 7 and 19 cores, and three programmable AoD
nodes, supporting sliceable and bandwidth-variableself-homodyne spatial superchannels. We demonstrated SDN-controlled automatic bandwidth and QoTprovisioning over the SDM infrastructure, AoD nodeconfiguration, and self-homodyne spatial superchannel
slicing, routing and switching according to user requirements and with good end-to-end performance.
Acknowledgements
This work is supported by the EPSRC grant EP/I01196X: The Photonics Hyperhighway, and the EC
FP7, grant no. 317999, IDEALIST. The authors are
grateful to Furukawa Electric from Japan for providing
the 7-core MCF and to Kylia for the 16QAM emulator.
References
1 Jun Sakaguchi et al., OFC 2012, PDP5C.1., (2012)
2 Takara et al., ECOC 2012, PDP Th.3.C.1. (2012)
3 M. D. Feuer et al., OFC 2013, PDP5B.8. (2013)
4 Puttnam et al., IEEE Summer Topicals 2013, TuC1.2.
5 Sakaguchi et al., IEEE Summer Top. 2013, WC1.2
6 N. Amaya et al., ECOC 2012, PDP Th.3.D.3 (2012).