Evaluation of Virtualization Models for Optical Connectivity Service Providers
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The document discusses the evaluation of virtualization models for optical transport networks, emphasizing the importance of software-defined networking (SDN) in enhancing programmability and operational efficiency. It outlines the principle of separating the control and data planes, allowing for better abstraction and management of optical resources, as well as the need for standardized protocols and interfaces. Challenges such as vendor lock-in, complexity, and the need for visibility of static and dynamic constraints are highlighted, alongside the role of network hypervisors in achieving effective optical network virtualization.
Evaluation of Virtualization Models for Optical Connectivity Service Providers
- 1. Achim Autenrieth1, Thomas Szyrkowiec1,2, Klaus Grobe1, Jörg-Peter Elbers1, Paweł Kaczmarek1, Paweł Kostecki1, Wolfgang Kellerer2 1) ADVA Optical Networking 2) Technische Universtität München Optical Network Design and Modeling (ONDM) 19-22 May 2014, Stockholm, Sweden Evaluation of Virtualization Models for Optical Connectivity Service Providers
- 2. © 2014 ADVA Optical Networking. All rights reserved.22 NMS / CP / SDN Mission Key Facts Transport SDN for Flexible Optical Networks • Datacenter Connectivity • Cloud Bursting • Secure multi- tenancy • Global network visibility with “real-time” control • De-couple virtual from physical network • NFV support From cloud access to optical Terabit/s connectivity Use Cases and Drivers Enablers DC Site 1 MAN / WAN DC Site NEnterprise Tenant B cloud Tenant C cloudTenant A cloud • Network Abstraction • Virtualization • Open & standardized interfaces • Multi-tenancy capability • Integration with existing OSS / NMS / CP SDN turns the network into a programmable resource
- 3. © 2014 ADVA Optical Networking. All rights reserved.33 Transport SDN – Early Attempts “If all you have is a hammer, everything looks like a nail.” Abraham Maslow, 1966 Transport SDN is much more than OpenFlow and protocol extensions.
- 4. © 2014 ADVA Optical Networking. All rights reserved.44 What is SDN? Open Networking Foundation white paper In the SDN architecture, the control and data planes are decoupled, network intelligence and state are logically centralized, and the underlying network infrastructure is abstracted from the applications. • SDN is an architectural framework for creating intelligent networks that are programmable, application aware, and more open. • SDN allows the network to transform into a more effective business enabler. • SDN enables applications to request and manipulate services provided by the network and allows the network to expose network state back to the applications. • A key aspect to the architectural framework is the separation of forwarding from control plane, and establishment of standard protocols and abstractions AT&T Domain 2.0 Vision white paper How does SDN apply to Optical Transport Networks?
- 5. © 2014 ADVA Optical Networking. All rights reserved.55 “Legacy”Transport Network programmability HW abstraction and virtualization Centralized management & control Flow/circuit oriented data plane SDN vs. “Legacy” Optical Transport Separation of data and control plane SDN Principles Top-down approach: Facilitate optical layer abstraction, virtualization & programmability.
- 6. © 2014 ADVA Optical Networking. All rights reserved.66 Direct How to Achieve Abstraction and Virtualization in Optical Networks? SDN Controller (Abstract Model)SDN Controller (Direct Model) Abstract (Overlay) Network Hypervisor • Direct model with open, standardized API and data models yields potential benefits at cost of complexity and latency • Suited for multi-vendor management integration • Current protocols not mature enough – Standardization required (ONF OTWG) • Abstract model allows abstraction from analog complexity; • Well suited for Virtualization and Orchestration • Network Hypervisor key element to provide network abstraction, virtualization, and multi-tenancy in abstract model This talk focuses on abstract model for optical network virtualization
- 7. © 2014 ADVA Optical Networking. All rights reserved.77 How Transport Fits in SDN Model Network Hypervisor User Interfaces 3rd Party Apps Transport Apps Optical Network Controller Management Fault & Alarms Configuration Accounting Performance Security Control Topology Disc Path Compute Provisioning Resource Mgr Policy Mgr Database Flow DB Topology DB Resource DB Policy DB Optical Network Hypervisor Network Hypervisor Storage Compute Optical Network Orchestration SDN Orchestration • Hypervisors allowed Storage and Compute resources to be managed together. • SDN allowed Networking to join through an Orchestration layer • Transport is added by extending the SDN controller function. Network Hypervisor virtualizes the optical network and presents an abstracted view to the SDN controller SDN Controller
- 8. © 2014 ADVA Optical Networking. All rights reserved.88 Optical Network Hypervisor Architecture WAN is exposed as virtual topology using OpenFlow or Restful API. SDN Controller #2 SDN Controller #1 Provider Controller SDN Controller #3 Optical Network Hypervisor NMS /OSS SNMP, NETCONF OF, NETCONF, RESTful API OF, NETCONF, PCEP OF, PCEP, NETCONF GMPLS-ENNI, BGP-LS SNMP, MTOSI OpenFlow PCEP GMPLS-ENNIBGP-LS NETCONF/YANG REST AbstractionPhysicalressourcesDerivedtopology GMPLS
- 9. © 2014 ADVA Optical Networking. All rights reserved.99 Optical Network Virtualization Challenges • Realities • Optical networks largely service packet and OTN networks today • Virtualization should adapt to fit OTN and packet network needs • Transport networks are centrally managed, familiar with managing complexity • Distributed protocols (GMPLS, etc.) are used • Logically-centralized functionalities available today to assist: PCE, TE DB, etc. • Real challenges of optical networks • Optical networks are usually built as vendor islands • Many deployed vendor-proprietary transport technologies • Element complexity, technology complexity, OA&M complexity ... • What‘s important to optical transport network virtualization • Complexity hiding (what happens in optical networks, stays in optical networks) • Constraints modeling (in IT terminology, without optical characteristics) Finding the appropriate level of abstraction is key to virtualization
- 10. © 2014 ADVA Optical Networking. All rights reserved.1010 Network Abstraction / Virtualization Options Abstract Link • “You can reach this destination across this domain with these characteristics” • Paths in the optical domain become links in the virtual topology • Allows vendor independent constraint modelling Virtual Switch • Hierarchical abstraction • Presents subnetwork as a virtual switch • Simple model, but can be deceptive • No easy way to advertise “limited cross- connect capabilities” Virtual Node aggregation hides internal connectivity issues and physical constraints Abstract Link aggregation needs compromises and frequent updates See also: Aihua Guo, "Network Virtualization", OFC 2014, M2B.5
- 11. © 2014 ADVA Optical Networking. All rights reserved.1111 Flexible Optical Circuit Switched (OCS) Transport Networks Packet Routers OTN / Ethernet Switches UNI/NNI NMS Optical Domain WSS WSS WSS WSS WSS ROADM GMPLS Control Plane
- 12. © 2014 ADVA Optical Networking. All rights reserved.1212 • Optical network-scope constraints and functions • Optical Performance Constraints • Wavelength Contention (ext.) • Sequential Lightpath Setup / Teardown • Optical Power Balancing Optical Network != Generic Hardware a) 40km b) 60km c) 20km a) b) c) d) d) WSS WSS WSS WSS WSS Fixed / Tunable transponders Colorless Module(s) Line Ports Directionless Module External Wavelengths Regenerators Modular structure and analog nature of ROADMs introduce node-scope and network-scope constraints • Modular ROADM structure with node-scope constraints
- 13. © 2014 ADVA Optical Networking. All rights reserved.1313 Constraints in an Optical Node • Transponder tunable range constraint (TTR) • Fixed transponder is a special case of TTR • To be exposed as tunability constraints to client layer for packet- optical integration (where packet routers connects optically to the colorless ROADM of optical network) • Lambda selection group (LSG) • Transponder tunable range constraint, network degree • Edge binding constraint (EBC) • Array of { transponder ID, lambda selection group } • To be exposed as generic mutual exclusivity to client layer • Resource grouping constraints (RGC) • Representation of shared resource exclusion between groups of transponders; may be identified by the ID of their connected multiplexers or ROADMs • To be exposed to virtual networks as resource sharing constraints • Transit binding constraint (TBC) • Table of {incoming lambda channel, incoming network degree, outgoing lambda channel, outgoing network degree} • Important for computing path for virtual overlay networks • Regenerator binding constraints (RBC) • Array of { LSG of incoming regenerator port, incoming ROADM line port, LSG of outgoing regenerator port, outgoing ROADM line port } • Important for computing path for virtual overlay networks WSS WSS WSS WSS WSS Fixed / Tunable transponders External Wavelengths Regen. Fixed Filter Today, these constraints cannot be disseminated and mapped to client layers Network Level Abstraction required Aihua Guo, OFC 2014, M2B.5
- 14. © 2014 ADVA Optical Networking. All rights reserved.1414 Sample ROADM network WSS WSS CL WSS CL WSS TPB1 WSS WSS DL WSS CL WSS TPA1 Node A (13) Node C (15) WSS WSS DL WSS CCM40/8 TPC1 Node B (14) Colorless Directionless ROADM Colorless Directionless ROADM Colorless Directionless ROADM MXPA2 MXPB2 Node A Node C Node B
- 15. © 2014 ADVA Optical Networking. All rights reserved.1515 • Single Ethernet Port Switch • Only client ports present • Lightpath is mapped to a bidirectional FLOW_MOD or two uni-directional FLOW_MODs (which must be correlated) • Very simple model, easy to integrate in IT orchestration systems Single Virtual Switch Model Modelling of static constraints Geography No Optical performance (Reach) No Feasible Port Connectivity No Optical parameters (Tunablility) Some (OF 1.4) Modelling of dynamic optical constraints WL-Blocking No Internal contention No 10 10
- 16. © 2014 ADVA Optical Networking. All rights reserved.1616 • Each NE is mapped to a Virtual Switch • Feasible Lightpaths can be instantiated as abstract links • Abstract links can be automatically detected by OF-Controller • Lightpath is mapped to two bidirectional FLOW_MODS or four unidirectional FLOW_MODS (which must be correlated) Abstract Link Model – One Switch per NE Modelling of static constraints Geography Yes Optical performance (Reach) Yes Feasible Port Connectivity No Optical parameters (Tunablility) Some (OF 1.4) Modelling of dynamic optical constraints WL-Blocking Yes Internal contention Partly A B C (A) (C) A B C
- 17. © 2014 ADVA Optical Networking. All rights reserved.1717 • Each network port of a line card (TP / MXP) is mapped to a Virtual Switch • Feasible Lightpaths can be instantiated as abstract links • Abstract links can be automatically detected by OF-Controller • Lightpath is mapped to two bidirectional FLOW_MODS or four unidirectional FLOW_MODS (which must be correlated) Abstract Link Module – One Switch per Line Card Modelling of static constraints Geography Partly Optical performance (Reach) Yes Feasible Port Connectivity Yes Optical parameters (Tunablility) Some (OF 1.4) Modelling of dynamic optical constraints WL-Blocking Yes Internal contention Partly MXP A2 TP A1 TP B A2 C1 C2 B A1 TP C1 MXP C2
- 18. © 2014 ADVA Optical Networking. All rights reserved.1818 Abstract Link Module – One Switch per Client Port Exposed topology dynamically changes based on dynamic constraints
- 19. © 2014 ADVA Optical Networking. All rights reserved.1919 Summary • Transport SDN: Programmability & virtualization of optical networks. • Improves network efficiency. Simpler operation is real opportunity. • Basic standards and protocols are there, but require further work • Abstraction of optical network is required, but static and dynamic constraints should be visible • Definition of open interfaces (esp. north, east, west) is crucial. • Trials and interoperability demos are necessary.
- 20. © 2014 ADVA Optical Networking. All rights reserved.2020 Virtualization facilitated by Network Hypervisor and commercial control plane. TNC2014 Demonstration - SDN-controlled Optical Service Orchestration
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