network virtualization

Aihua GuoMarch 2014

Network Virtualization

© 2014 ADVA Optical 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


Optical Transport Networks

Optical transport networks increasingly asked to provide dynamic, high bandwidth, programmable services

Optical transport networks increasingly asked to provide dynamic, high bandwidth, programmable services

Packet Routers

OTN Switches

UNI/NNI

NMS

Optical Domain

XPD

RX

PD

RX

PD

RX

PD

R


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


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?


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 ...


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...


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


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


Optical Node ConfigurationNetwork

Degree 2

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

EX

TE

RN

AL

Tunable transponders

Network

Degree 1 Network

Degree 3

Colorless

ROADM

Directionless

ROADM

Directional

ROADM

Fixed FilterFixed Filter

XPD

R

XPD

R

PR

OT

External Wavelength

Transponder Protection

Fixed – Tunable Regeneration

Tunable – Tunable Regeneration

Fixed transponders


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

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

EX

TE

RN

AL


Network

Degree 1 Network

Degree 3

Colorless

ROADM

Directionless

ROADM

Directional

ROADM


XPD

R

XPD

R

PR

OT

External Wavelength




Fixed transponders

Tunable Port ID 1 Grid ID 1 Lamba Offset 1


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 groupEdge binding

constraint


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

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

EX

TE

RN

AL


Network

Degree 1 Network

Degree 3

Colorless

ROADM

Directionless

ROADM

Directional

ROADM


XPD

R

XPD

R

PR

OT

External Wavelength




Fixed transponders




...

Resource Group ID

Virtual Link

Resource grouping constraint


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

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

XPD

R

EX

TE

RN

AL


Network

Degree 1 Network

Degree 3

Colorless

ROADM

Directionless

ROADM

Directional

ROADM


XPD

R

XPD

R

PR

OT

External Wavelength




Fixed transponders

Tunable Port ID 1

Grid ID 1

Lamba Offset 1

Network Degree 1

+

Transponder tunable range constraintLambda 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

+


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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network virtualization

Technology

optical network virtualization

realities optical networks

adva optical networking

scope optical constraints

clients virtual networks

packet optical integration

otn networks

physical networks