From GMPLS to OpenFlow Control & Monitoring of Optical Networks

From GMPLS to OpenFlow Control&Monitoringof Optical Networks

Piero Castoldi

Workshop “(G)MPLS and OpenFlow: Interworking, Integrating, or Replacing?”

Dublin, May 7 2013

Acknowledgements (people): A.Giorgetti, F. Cugini, F. Paolucci, B. Martini, N. Sambo, M. Gharbauoi, A. Sgambelluri, D. Adami

Acknowledgements (projects): STRONGEST, IDEALIST, OFELIA

© 2013 Scuola Superiore Sant’Anna

Outline

• Introduction on optical network management and control

• Emergence of Software Defined Networks• A couple of specific implementations for flexible optical networks

– Control of Optical Network through OpenFlow– Monitoring Experiments of Optical Networks through

OpenFlow


There was the centralized management of ON ..

Static NMS

1

• Management plane: coordination of network elements to configure, analyze and monitor network resources to guarantee network operation � “FCAPS” functions– Fault management: detecting failures and isolating

failed component– Configuration management: managing orderly

network changes e.g. equipment addition/removal– Accounting management: billing and developing

component lifetime histories– Performance management: monitoring and

managing various network performance metrics– Security management: user authentication, control

access to network elements, user data protection etc.


From centralized to distributed GMPLS network control ..

Static NMS

1

2

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

• GMPLS CP aimed at enforcing automated connection management– Path computation– Connection establishment

and release– Fault recovery

• Routing– Open Shortest Path First with Traffic Engineering extensions, OSPF-TE

• Signaling – Resource Reservation Protocol with Traffic Engineering extensions, RSVP-TE

• Link Management– Link Management Protocol LMP

• Path Computation– Distributed: locally performed at the source node that receives the connection

request


Some functions returned centralized ..

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

PCEPCEPCEPCE

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

PCEPCEPCEPCEPCEPCEPCEPCEStatic NMS

1

2

3

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

• Path Computation– Centralized: performed in a Path Computation Element communicating with the

connection source node using the Path Computation Element Protocol (PCEP)

• PCE maintains a TED– Updated by means of the LSA flooded by the running OSPF-TE routing protocol– Updated by means of direct communication with the network nodes

• Stateful PCE– Besides the TED, also information about the previously computed path are utilized

during path computation

• Stateless PCE– Only the information stored in the TED are used for path computation


Impairment awareness in GMPLS CP

GMPLS lightweight extensions to RSVP-TE signaling protocol encompass physical impairment awareness degradation in all-optical networks:• Encompassing an OSNR model that accounts for physical attenuation, Polarization Mode Dispersion (PMD), Chromatic Dispersion (CD) and Self Phase Modulation (SPM), to identify thebest wavelength assignment.• Encompassing crosstalk effect via the Crosstalk Vector (XV) object to identify the preferred wavelengths, e.g. the ones withminimum added crosstalk.• Encompassing the use of shared regenerators thanks in a distributed way (object accounting for already used regeneratorsand explicit flag for regeneration)


Emergence of Software Defined Networks

7


• Software-defined networking (SDN) emerged as a new paradigm that decouples physical network implementation from network control logic.

• Data plane functions (forwarding) reside within network elements (switches, routers)

• Control plane functions (routing, signaling) are moved to a separate dedicated controller

• Network Services are realized through dedicated APPlicationsrunning within the Controller OS

Network

Network Services

Software Defined Network

Controller(s) (e.g. NOX)

APP1(e.g., Access

Control)

APP2 (e.g.,Protected

path)

APP3(e.g., network

defrag)

Legacy Network devices

NMS-based

network

EM Intf

NMS Adap

GMPLS-

based

network

SNMP

SNMP

OF-based

network

OF Intf

OpenFlow

Software Defined Networking


OpenFlow is SDN but not viceversa

• OF is currently the suggested interface by ONF between the controller and the OF-capable network device.

• OF is under consideration in several scenarios such as: carrier grade Ethernet, and optical transport networks.

• The controller manages the switching elements (i.eOpenFlow switches) by programming their flow tables.


The return of centralized control of optical networks

• OpenFlow is being adapted for controlling optical networks

• Key idea: OpenFlow controller perform path computation, node configuration, lightpath maintenance and monitoring functions through unique, open, standard protocol (OPEX reduction with respect to distributed GMPLS suite)

• E.g In flexible optical networks, additional parameters can be considered for lightpath provisioning: modulation format, FEC, type of channel, allocated spectrum, transponder/receiver dynamic configuration

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

PCEPCEPCEPCE

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

PCEPCEPCEPCEPCEPCEPCEPCE

OpenFlow controller

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

OpenFlow controller

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

OpenFlow controllerOpenFlow controller

Static NMS

1

2

3

5

4

GMPLS controller

GMPLS controller

GMPLS controller

GMPLS controller

OF-GMPLS cooperation

GMPLS replacement by OF


GE/FE GE/FE

SDN/OF controller (NOX, Flowvisor)GMPLS control planeMiddleware (Ofelia control framework)

• Juniper M7i/M10 routers• Juniper EX3200/2200 switches• Cisco 7200 VXR router• Emulated OpenFlow switch

ROADMEricsson MHL30001 ch add-drop@ 10Gb/sDWDMGMPLS

CNIT-PisaOfelia island

Data Center OF controller

OpenFlowEthernet

ring

Network Facilitiesat SSSA/CNIT

Pisa


Control of Optical networks through OpenFlow

12


OF-GMPLS lightpath setup (cooperation mode)

• Source: request to OpenFlow controller• OpenFlow controller: routing

� TED update: previously routed requests

� OpenFlow controller: reply to source

• Source: RSVP-TE Path to destination� Explicit Route Object� Label Set Object� Suggested Label

• Destination: wavelength assignment• Destination: RSVP-TE Resv to source

� Resource reservation� OXC cross connections

• Lightpath established

OpenFlowOpenFlowOpenFlowOpenFlow controllercontrollercontrollercontroller

GMPLS GMPLS GMPLS GMPLS controllercontrollercontrollercontroller





OF lightpath setup(replacement mode)

• Source: request to OpenFlowcontroller

• OpenFlow controller: routing� TED updated: previously routed

requests

• Controller: flow configuration at each OXC

• Each OXC: flow configuration � Resource reservation

• OpenFlow controller: reply to source� OF-timer:

• Wait timer expiration without errors

� OF-ack: • Wait the last ack

• Lightpath established

OpenFlowOpenFlowOpenFlowOpenFlow controllercontrollercontrollercontroller

Controller

Data

Timer


OF-based flexi lightpath provisioning: OF-ACK scheme implementation

OF ControllerOF Controller

OFPT_LIGHTPATH_IN

OFPT_FLOW_MODOFPT_FLOW_MOD

OFPT_FLOW_MODOFPT_LIGHTPATH_OU

T

Messages: • lightpath_in (lightpath request)• flow_mod (set flow entry)• flow_ack (ack entry)• lightpath_out (lightpath setup

outcome)

• Switch-controller OF session over TCP

• Lightpath setup needs node configuration confirmation

• Provisioning Request-Reply maintained (PCEP-like)

• Fast parallel node configuration • Errors handling: no-path, failed

flow_mod


OpenFlow controller implementation

• Based on the PCE engine, path_solver + Controller_handler modules

• Performs path computation: route, spectrum assignment, modulation format and FEC assignment, impairment validation. Different IV and RSA strategies available (joint, IV+RSA)

• Performs node configuration (centralized signaling): Cross-connections, WSS spectrum shaping, TX/RX fine configuration, flexible submodules on/off

• Performs monitoring (statistics collection and analysis) and feedback-based optimization� Optical channel QoT parameters monitoring

� Degraded QoT triggers analysis (fault localization through cross-correlation) and decisions (e.g., lightpath re-routing, dynamic modulation format adaptation)

OF sessions

PathsolverPath

solver

Controller Handler

Controller Handler

OF interfaceOF interface

OF-TEDOF-TED

IV models

IV models

OF sessions

PathsolverPath

solver

Controller Handler

Controller Handler


OF-TEDOF-TED

IV models

IV models

PathsolverPath

solver

Controller Handler

Controller Handler


OF-TEDOF-TED

IV models

IV models


OpenFlow Switch implementation

• Port configuration (switch abstraction), state and statistics• Flow table storesactive entries (installedflows)• Device interface mapsconfiguration commands intohardware-specificcommands

OF switchhandler

OF switchhandler

Device interfaceDevice interface


Portconfig,state, stats

Portconfig,state, stats

Controller session

Flow tableFlow table

Switchhardware

Switchhardware


Flexi Optical ROADM/Switch abstraction

•Design relies on differentport types (fixed or flexible, depending on the switcharchitecture) and flexibletransponder/receiver•Flow entry format:•Intermediate hop: [in_port(transit), out_port (transit) ,assigned_ spectrum]•Src: [in_port (add), out_port(transit), assigned_spectrum, OCh_spec]•Dst: [in_port (transit), out_port (drop), assigned_spectrum, OCh_spec] •Spectrum collision checkperformed at each out_port

OUT_PORT [ ]

transit

IN_PORT [ ]

add

transit

drop

TXTX RXRX


Monitoring Experiments of Optical Networks through OpenFlow

19


Monitoring in OpenFlow-based networks

• OF-Controller responsible to compute and configure flow tables (i.e., forwarding tables) on OpenFlow switches

• Statistics are typically exchanged for manageability and monitoring functions. Symmetric messages (OFPT_STATS_REQUEST and OFTP_STATS_REPLY)

• Port status info may be exchanged to notify link failures.• New types of statistics are required in flexi-grid networks,

e.g.:� Quality of Transmission (QoT) statistics� OAM statistics

• OF-Controller may utilize statistics information to improve monitoring, fault notification, localization, etc.


Flexi optical network and monitoring enhancements

•BER and MSE statistics at coherent receiver (PM-16QAM, PM-QPSK)•OSNR, non-linear parameters, frequency offsets, equalizer coefficients (CDand PMD estimation)


OpenFlow monitoring statistics

• For each lightpath monitoring parameter, specific field within OFPT_STATS_PORT_LP structure is defined and managed in switches

• OF-Controller performs periodic requests at configurable time interval (DEFAULT_POLL_PORT_PERIOD, e.g. 1 min.)

• Polling rate may change according to network conditions

• OF-Controller enhanced with new IN_PATH vector storing also statistics. Each activated lightpath (unique DPID) includes IN_PATH including traversed links ->correlations among statistics and actual traversed resources are possible


Experimental demonstration (1)

• 4 lightpaths activated (L1-L4), 200Gb/s 16-QAM, coherent detection• BER monitoring updated every 1 min.• QoT degradation on link 3-4, time increasing• Warning and Critical thresholds set at OF-Controller, polling rate raises to 1s• Correlations : statistics and traversed link info stored within IN_PATH

-> Link 3-4 identified as possible degradation source

EDFA

Warning BER threshold

Critical BER threshold

L1

L4

L3

L2

BER statistics collected by OF-Controller


Experimental demonstration 2

• Bit Error Rate (BER) field enclosing current BER measurement at port PORT_NUMBER• Further actions applied by OF-Controller upon new requests:

1. Stronger modulation format while maintaining bit-rate (QPSK, 200G)2. 2 LSPs halving the bit-rate (QPSK, 100G)3. Different route (e.g., 3-2-1 with respect to 3-4-1)

Capture of OpenFlow messages

ModifiedModifiedModifiedModified OpenFlowOpenFlowOpenFlowOpenFlow StatsStatsStatsStats ReplyReplyReplyReply messagemessagemessagemessage


Research directions and open points

• OF controller and switch implementation extensions• Global re-optimization (e.g., OF-driven PushPull technique)• Protection and fast restoration solutions• Multicast (P2MP) support• OF multi-domain, multi-layer

• SDN alternative or complementary to distributed GMPLS for reliability?

• Recognized GMPLS advantage: efficient fast recovery• Potential SDN drawbacks: scalability issues, controller communication failure issues, complex disaster recovery

• Pure/mixed architectures to be considered and evaluated (e.g., pure OF, OF+ basic RSVP-TE, OF +RSVP-TE +LMP)

• OpenFlow controller and PCE: which relationship?


Recent Related recent publications

• A.Giorgetti, F. Cugini, F. Paolucci, P. Castoldi, “OpenFlow and PCE architectures in WavelengthSwitched Optical Networks”, ONDM 2012

• F. Paolucci, F. Cugini, N. Hussain, F. Fresi, L. Potì, “OpenFlow-based Flexible Optical Networks withEnhanced Monitoring Functionalities”, ECOC 2012

• N. Sambo, F. Paolucci, F. Cugini, M. Secondini, L. Potì, G. Berrettini, G. Meloni, F. Fresi, G. Bottari, P. Castoldi, “Software Defined Code-rate-adaptiveTerabit/s based on time-frequency Packing”, submitted to OFC/NFOEC 2013


EE--mail: [email protected]: [email protected]

thank you!thank you!

Technology

From GMPLS to OpenFlow Control & Monitoring of Optical Networks