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Network Virtualization
This document discusses network virtualization and its application to optical transport networks. It describes how network virtualization uses software abstraction to create logically isolated virtual networks. It then discusses some of the challenges in virtualizing complex optical networks, including technology differences between vendors. The document proposes using virtual overlay networks to virtualize optical networks while hiding their complexity from clients. It describes how optical networks can be exposed as virtual links or nodes to clients. Finally, it outlines various constraints in optical networks, like transponder tunability ranges, that would need to be abstracted and potentially exposed to properly construct virtual overlay networks over the physical optical domain.
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Network Virtualization
- 1. Aihua Guo March 2014 NetworkVirtualization
- 2. © 2014 ADVAOptical Networking. All rights reserved. Confidential.22 Network Virtualization • Using software-based abstraction to enable the creation of logically isolated virtual network representations atop physical networks • Enabling new applications, operation models and business opportunities
- 3. © 2014 ADVAOptical Networking. All rights reserved. Confidential.33 Optical Transport Networks Optical transport networks increasingly asked to provide dynamic, high bandwidth, programmable services Packet Routers OTN Switches UNI/NNI NMS Optical Domain 1xNWSS 1xNWSS 1xN WSS 1xN WSS 1xN WSS XPDR XPDR XPDR XPDR
- 4. © 2014 ADVAOptical Networking. All rights reserved. Confidential.44 Virtualizing the Optical Transport Networks • 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 ... • Realities • Optical networks largely service packet and OTN networks today • Transport networks are centrally managed, familiar with managing complexity • What‘s important to optical transport network virtualization • Complexity hiding; what happens in optical networks, stays in optical networks • Finding the appropriate level of abstraction is key to virtualization
- 5. © 2014 ADVAOptical Networking. All rights reserved. Confidential.55 Virtualization Can Start Real Simple... • Virtualize the optical networks as a single virtual switch to its clients SDN Adapter Virtual Networks But, considering the following client‘s requirement to configure a virtual network • Bandwidth • Latency • Fate sharing • Recovery capabilities, etc. Plus the optical network complexity • Connectivity constraint, aka switch asymmetricity • Optical impairment • ROADMs, CDC... ...is simple connectivity still sufficient for optical network virtualization?
- 6. © 2014 ADVAOptical Networking. All rights reserved. Confidential.66 Virtual Overlay Networks • Simple connectivity no longer enough; richer model needed • Endpoints are nodes in a topology; bandwidth and latency are attributes of links and nodes in a topology; fate sharing determined by the structure of a topology; recovery capabilities for a flow determined by the containing topology ...
- 7. © 2014 ADVAOptical Networking. All rights reserved. Confidential.77 Virtual Overlay Networks • Virtualization may be achieved by means of constructing virtual overlay networks • Server network aspects expressed to client network in client terms • Client network methods and techniques can remain unchanged • True for traditional EMS/NMS, distributed control plane, emerging SDN • Overlay networks already much in use within client layer SDN today • Reuse established expertise in the optical domain: PCE, traffic engineering...
- 8. © 2014 ADVAOptical Networking. All rights reserved. Confidential.88 Network Scope Virtualization • Virtual overlay networks may be presented in different ways... Server Client Virtual Link Server Client Virtual Node Connectivity Information • Paths in the optical domain become links in its client‘s virtual networks OR Or, a combination of both… • Optical networks become virtual nodes in its client‘s virtual networks
- 9. © 2014 ADVAOptical Networking. All rights reserved. Confidential.99 Node Scope Virtualization • Optical elements have wide range of network and node scope constraints • Wavelength continuity (e.g. optically transparent nodes) • Optical impairment • Fixed filter structures (e.g. endpoint transponders fixed to specific degree) • Regenerator diversity (e.g. some tunable, some fixed) • Endpoint diversity (e.g. transponder ports may be fixed, tunable, switchable, combo) • Abstraction of node-scope optical constraints are necessary to support proper construction of virtual overlayer networks; some may be exposed as constraints to clients. • Key is to find the appropriate level of abstraction
- 10. © 2014 ADVAOptical Networking. All rights reserved. Confidential.1010 Optical Node Configuration Network Degree 2 1xNWSS 1xNWSS 1xN WSS 1xN WSS 1xN WSS XPDR XPDR XPDR XPDR XPDR XPDR XPDR XPDR EXTERNAL Tunable transponders Network Degree 1 Network Degree 3 Colorless ROADM Directionless ROADM Directional ROADM Fixed Filter XPDR XPDR PROT External Wavelength Transponder Protection Fixed – Tunable Regeneration Tunable – Tunable Regeneration Fixed transponders
- 11. © 2014 ADVAOptical Networking. All rights reserved. Confidential.1111 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 1xNWSS 1xNWSS 1xN WSS 1xN WSS 1xN WSS XPDR XPDR XPDR XPDR XPDR XPDR XPDR XPDR EXTERNAL Tunable transponders Network Degree 1 Network Degree 3 Colorless ROADM Directionless ROADM Directional ROADM Fixed Filter XPDR XPDR PROT External Wavelength Transponder Protection Fixed – Tunable Regeneration Tunable – Tunable Regeneration Fixed transponders Tunable Port ID 1 Grid ID 1 Lamba Offset 1 Tunable Port ID 2 Grid ID 2 Lamba Offset 2 XPDR Network Degree 1 Network Degree 2 + + Transponder tunable range constraint Virtual Link Tunable Port ID 1 Grid ID 1 Lamba Offset 1 Network Degree 2+ Tunable Port ID 2 Grid ID 2 Lamba Offset 2 Network Degree 1+ … … Lambda selection group Edge binding constraint
- 12. © 2014 ADVAOptical Networking. All rights reserved. Confidential.1212 Constraints in an Optical Node • 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 1xNWSS 1xNWSS 1xN WSS 1xN WSS 1xN WSS XPDR XPDR XPDR XPDR XPDR XPDR XPDR XPDR EXTERNAL Tunable transponders Network Degree 1 Network Degree 3 Colorless ROADM Directionless ROADM Directional ROADM Fixed Filter XPDR XPDR PROT External Wavelength Transponder Protection Fixed – Tunable Regeneration Tunable – Tunable Regeneration Fixed transponders Tunable Port ID 1 Grid ID 1 Lamba Offset 1 Tunable Port ID 2 Grid ID 2 Lamba Offset 2 Tunable Port ID 3 Grid ID 3 Lamba Offset 3 ... Resource Group ID Virtual Link Resource grouping constraint
- 13. © 2014 ADVAOptical Networking. All rights reserved. Confidential.1313 Constraints in an Optical Node • 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 network degree, LSG of outgoing regenerator port, outgoing network degree } • Important for computing path for virtual overlay networks 1xNWSS 1xNWSS 1xN WSS 1xN WSS 1xN WSS XPDR XPDR XPDR XPDR XPDR XPDR XPDR XPDR EXTERNAL Tunable transponders Network Degree 1 Network Degree 3 Colorless ROADM Directionless ROADM Directional ROADM Fixed Filter XPDR XPDR PROT External Wavelength Transponder Protection Fixed – Tunable Regeneration Tunable – Tunable Regeneration Fixed transponders Tunable Port ID 1 Grid ID 1 Lamba Offset 1 Network Degree 1 + Transponder tunable range constraint Lambda selection group Tunable Port ID 2 Grid ID 2 Lamba Offset 2 Network Degree 2 + … Tunable Port ID 3 Grid ID 3 Lamba Offset 3 Network Degree 3 + Tunable Port ID 4 Grid ID 4 Lamba Offset 4 Network Degree 4 +
- 14. © 2014 ADVAOptical Networking. All rights reserved. Confidential.1414 Summary • Optical networks can be virtualized for dynamic, multi-tenant operations • Optical transport networks have complexities • A continuum of techniques needed to realize benefits • Virtualization initially bring transport into SDN • Providers use virtual overlay networks to enable SDNs for clients • "Infrastructure-as-a-Service", "Just Enough Topology" models • Virtualization of optical networks build on top of established expertise • Optical networks may be exposed as virtual overlay networks consisting virtual links, virtual nodes, or any combination of both to the clients • Node scope virtualization requires proper abstractions and exposing of optical constraints
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