Our Advanced Technology team was invited to present these slides at the Optical Network Design and Modeling (ONDM) conference in Stockholm, Sweden, along with a representative from the Technical University in Munich. Check out what they had to say about virtualization models

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?

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“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.

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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

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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

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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

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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

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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

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• 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

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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
• 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

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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

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• 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

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• 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

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• 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

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Abstract Link Module –
One Switch per Client Port
Exposed topology dynamically changes based on dynamic constraints

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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.

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Virtualization facilitated by Network Hypervisor and commercial control plane.
TNC2014 Demonstration - SDN-controlled
Optical Service Orchestration

21. Thank You
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