1. Aihua Guo
March 2014
Network Virtualization

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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

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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

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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

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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?

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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 ...

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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...

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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

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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

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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

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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

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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 ADVA Optical 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 ADVA Optical 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

15. aguo@advaoptical.com
Thank You
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