Evaluation of Virtualization Models for Optical Connectivity Service Providers

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

© 2014 ADVA Optical Networking. All rights reserved. 2 2

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 N Enterprise

Tenant B cloud

Tenant C cloud Tenant A cloud

Automate connectivity of multi-tier system patterns (Lower OpEx)

• Network Abstraction

• Virtualization

• Open & standardized interfaces

• Multi-tenancy capability

• Integration with existing OSS / NMS / CP

SDN turns the network into a programmable resource


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.


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?


“Legacy”

Tra

nsport

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.


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


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


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-ENNI BGP-LS NETCONF/YANG

REST

Ab

str

acti

on

Physic

al re

ssourc

es

Derived t

opolo

gy

GMPLS


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


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


Flexible Optical Circuit Switched (OCS) Transport Networks

Packet Routers

OTN / Ethernet Switches

UNI/NNI

NMS

Optical Domain

WS

S

WSS

WS

S

WSS

WSS

ROADM

GMPLS Control Plane


• 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


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


Sample ROADM network

WSS W

SS

CL WSS CL WSS

TP B

1

WSS W

SS

DL WSS

CL WSS

TP A

1

Node A (13)

Node C (15)

WSS W

SS

DL WSS

CCM40/8

TP C

1

Node B (14)

Colorless Directionless ROADM



MXP A

2

MXP B

2

Node A

Node C

Node B


• 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


• 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


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


• 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


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


Abstract Link Module – One Switch per Client Port

Exposed topology dynamically changes based on dynamic constraints


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.


Virtualization facilitated by Network Hypervisor and commercial control plane.

TNC2014 Demonstration - SDN-controlled Optical Service Orchestration

Thank You

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Technology

Evaluation of Virtualization Models for Optical Connectivity Service Providers