Automatically Switched Optical Networks (ASON): Main features and possible architectures

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1 Automatically Switched Optical Networks (ASON): Main features and possible architectures Jacques Robadey, Daniel Rodellar Swisscom Corporate Technology

2 P1012 FASHION project Flexible, Automatically SwitcHed, client Independent Optical Networks ASON Main features and possible architectures 2

3 Outline Project motivation ASON model ASON transport services ASON architectures Migration towards ASON Conclusions ASON Main features and possible architectures 3

4 Motivation Voice traffic growing slowly Fast growth of Internet traffic: highly dynamic highly asymmetric less profitable Transport networks should be adapted Traffic 1997 Data Voice time 2001 ASON Main features and possible architectures 4

5 ASON model Network Management Client Equipment UNI OCC NNI OCC OCC Control Plane OXC OXC OXC Transport Plane Signalling to open and close Optical Channels (OCh) - soft-permanent OCh (management + NNI signalling) - automatic OCh (UNI + NNI signalling) Dynamic coordination between client and optical network ASON Main features and possible architectures 5

6 Transport services Permanent OCh Soft-permanent OCh Switched Och Optical VPN Lambda trunking ASON Main features and possible architectures 6

7 Overlay model 2 client control plane client layer UNI 2 optical control plane optical layer 6 2 control planes, UNI is used to demand and establish connections Advantages: no visibility of the optical topology to the client layer, client-independent, optical layer keeps the control of the optical transport plane Disadvantages: 2 control planes, low interoperability ASON Main features and possible architectures 7

8 Peer model A single control plane Advantages: better interoperability, more efficient survivability Disadvantages: optical topology is visible to the client layer weakly adapted to non-ip clients optical layer = slave and not server of the client layer optical layer looses the control of the optical transport plane 1 2 Optical and Client control plane ASON Main features and possible architectures 8

9 Functionality Control plane Topology discovery Optical routing Signalling OCh switching Failure detection Restoration Policing & CAC CoS handling Transport plane OCh crossconnection Wavelength conversion Optical multiplexing Failure detection Protection ASON Main features and possible architectures 9

10 Architecture Scenarios Network solutions are proposed for features such as: - topology - nodes - grooming - resilience - routing - wavelength assignment - signaling - Traffic Engineering - UNI Selected architecture scenario in next slides ASON Main features and possible architectures 10

11 Routing, signalling, traffic engineering, wavelength assignment and UNI Routing: an enhanced SPF algorithm Signalling: PNNI or GMPLS extensions of CR-LDP and RSVP-TE Traffic engineering must perform load balancing to use the least loaded path Studied wavelength assignment algorithms: First Fit, LU, MU and Relative Capacity Loss UNI : OIF UNI ASON Main features and possible architectures 11

12 Resilience mechanisms Six resilience mechanisms have been analyzed: 1+1 protection Shared protection (n:m) with priority levels Fast recovery with pre-calculated restoration routes Pure restoration by calculating the restoration route after the failure No protection: the channel is simply dropped in case of a failure Best effort: not protected on spare resources and channel will be preempted to restore higher priority traffic These resilience mechanisms can correspond to CoS ASON Main features and possible architectures 12

13 ASON nodes: a critical issue INTELLIGENT Transp Transp OXC Transp Transp ASON Termination Grooming Wavelength Client Edge Network ( e.g. regional) Sub-Wavelength Client ASON Main features and possible architectures 13

14 Transparency and topology (1) ASON functionality must be available in both opaque and transparent networks Although optical X-connects are emerging pure optical transmission through many nodes is critical. new functionality is necessary for signalling and routing, neighbour and port discovery ASON Main features and possible architectures 14

15 Transparency and topology (2) We propose either opaque networks or a network with optical islands. ASON Main features and possible architectures 15

16 Sub-rate channel aggregation STM1 ATM FR GbE client interfaces IP router (possible POS) or GbE switch/router SDH Multiplexer G.709 Multiplexer lambda channels ASON Main features and possible architectures 16

17 Migration towards ASON Service evolution: permanent OChs (OTN) soft-permanent (could be done by TMN with fast provisioning) (short term ASON) automatic with UNI (long term ASON) Functionality evolution Topology and architecture: from pt to pt transmission to mesh networks. Management: TMN can be used together with an ASON control plane in a first phase. From centralised to distributed. Control plane: overlay model first, augmented model after, peer model perhaps later ASON Main features and possible architectures 17

18 Conclusions (1) Network services and functionality were defined in the study of the project Architecture features were chosen for: Topology Node definition Grooming Routing, Signalling Wavelength assignment Traffic engineering Protection UNI ASON Main features and possible architectures 18

19 Conclusions (2) ASON is proposed by ITU-T and driven by OXC equipment to support dynamic traffic demands and fast provisioning of Optical Channels ASON can support asymmetric traffic demands It is a multi-client network solution (not only IP) Different types of protection/restoration can be implemented (support different CoS) Support of OVPN Distributed control through the Control Plane ASON Main features and possible architectures 19

20 Conclusions (3) Techno-economical study of selected architectures Next presentation by Roberto Clemente Goal: Simulate, plan and compare different ASON scenarios ASON Main features and possible architectures 20

21 Thank you for your attention! Control Plane User Control Data NE NE NE Further information: Transport Plane NE NE ASON Main features and possible architectures 21