The Need for SDN in Orchestration of IP over Optical Multi-Vendor

Networks

Ori Gerstel, CTO, Sedona Systems

Victor Lopez, GCTO team, Telefonica

Acknowledgement: ACINO project, EU grant 645127

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Outline

• What is SDN? What is ML control about?

• When is central control necessary?

• Different forms of control distribution

• Experimental validation

What is SDN (in 1 slide)• A control architecture that is based on centralized

control instead of distributed control• Why?

• Simpler design/code than a distributed solution• Opportunity to commoditize the hardware• Open for 3rd party app development• More optimal global decisions

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CP CP CP

Distributed architecture (PMO) Centralized architecture

SDN

Data Data Data Data Data Data

What is SDN (more realistic definition)

• A control architecture that is based on some centralized control instead of fully distributed control

• Why?• Existing gear will live in the network for many years• Some functions are better implemented in distributed fashion• The risk of moving to a disruptive new architecture is too high

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Hybrid architecture

SDN

CP CP CPData Data Data

What does ML control enable?

• Streamlined operation

• Multi-layer restoration and optimization

• Multi-layer services

Multi-layer discovery and visibility

Always-accurate network view

Learn topology and traffic in each layer

Learn cross layer mapping

Cross-layer awareness

Reduced service downtime

Provision L3 links with optical SRLGs

Reroute optical connections to provide more diversity

Coordinated maintenance

?

Safe operations

Restoration

CAPEX savings

Optimization

Adaptive network

Cloud Burst

Economical 10/100G BoD

Private link

Outline

• What is SDN? What is ML control about?

• When is central control necessary?

• Different forms of control distribution

• Experimental validation

Optical controller requirements

• Get topology, links & ports

• Get connections & their path

• Set up new connections with path constraints

• Define optical restoration properties for connections

• Push alarms

• Compute feasible paths (PCE)

http://sedonasys.com/what-multi-layer-control-requires-from-the-controllers-for-each-layer/

IP controller requirements• Get topology, links & ports• Get LSP, their path &

reserved/actual bandwidth• Get e2e IP traffic matrix• Push alarms• Simulate IP layer behavior under

link add/remove• Add IP link & configure its

properties• Cost out IP link

http://sedonasys.com/what-multi-layer-control-requires-from-the-controllers-for-each-layer/

What is ML control about?

Optical brain IP brainML brain

Network Network

Requires collection of a lot of global data+ heavy processing of the data+ lots of back and forth negotiation extremely complex in a distributed fashion= Central control

Does this mean distributed control is dead?

• No

• Distributed control is useful inside a vendor domain• Connection set up• Restoration

• Distributed control is useful between orchestrators of different Service Provides• East-West interface

Domain DomainDomain Domain

Orchestrator Orchestrator

Controller Controller Controller Controller

Does this mean distributed control is dead?

• NNI? Probably dead

• UNI? Useful for corner cases• IPoDWDM + restoration + WL change

Domain DomainDomain Domain

Orchestrator Orchestrator

Controller Controller Controller Controller

Outline

• What is SDN? What is ML control about?

• When is central control necessary?

• Different forms of control distribution

• Experimental validation

Different forms of control distribution (outline)

• Network control architecture

• Internal controller architecture

• Multi-layer/vendor architecture

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Hybrid control models(OFC’15)

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Initiation Policy decision

Path selection

Path setup

Distributed model

Central path compute model

Policy provisioning model

Centralized model

• Initiation: who decides to set up the path?

• Policy decision: who decides about the constraints for the path?

• Path selection: who decides how to route the path?

• Path setup: who configures the nodes along the path – and (typically) who restores it?

Hybrid control models(OFC’15)

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Initiation Policy decision

Path selection

Path setup

Distributed model D D D D

Central path compute model D D C [+D] D

Policy provisioning model C C D D

Centralized model C C C C

Hybrid control models(OFC’15)

• Setup initiated by the central controller

• It decides on the constraints and provisions the head-end with one or more policies

• The head-end computes the path based on the policies

• The path is set up via distributed signaling (RSVP)

• The network retains autonomous actions (e.g., restoration)

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Initiation Policy decision

Path selection

Path setup

Distributed model D D D D

Central path compute model D D C [+D] D

Policy provisioning model C C D D

Centralized model C C C C

R1 R3

O1

O2

O3

SDN

controller

3. GMPLS-UNI creates the

optical circuit leveraging

WSON

3

2. SDN controller triggers

creation of new link by

provisioning the router with

policies

2

Hybrid control example

1a

1. SDN controller learns

optical network from (a)

Optical layer, (b) IP layer

1b

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4. Upon failure GMPLS

acts according to the

policies

Hybrid distributed and centralized control – not our invention…

Centralized control

Distributed control

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Different forms of control distribution (outline)

• Network control architecture

• Internal controller architecture

• Multi-layer/vendor architecture

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Carrier grade requirements

• Typical carrier-grade req.s for the controller:1. It must survive HW/SW failures

2. It may have to keep working during SW upgrades

3. It may have to scale to a large number of transactions

• (Some of these req.s are not mandatory if the controller is not involvedin real-time operation)

Distributed systems address these req.s

• A failure of one copy does not affect other ones

• Upgrade of one copy allows other copies to continue working

• The workload can be distributed amongst multiple copies

Distributed systems address these req.s

• Typical solution: use distributed database to keep all copies in sync

• Note: this does not imply we’re back to complex distributed systems

Controller

Adapter

NE

Adapter

NE

Apps

Network DB

Controller

Adapter

NE

Adapter

NE

Apps

Controller

Adapter

NE

Adapter

NE

Apps

Controller

Adapter

NE

Adapter

NE

Apps

Distributed network DB

Different forms of control distribution (outline)

• Network control architecture

• Internal controller architecture

• Multi-layer/vendor architecture

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Monolithic SDN architecture

Monolithic SDN controller

ML App

30

• Monolithic approach: • Single controller controlling

multiple layers and vendors

• Concerns:• Complex to manage

• Complex to troubleshoot

• Complex to upgrade

• Recreating some of the issues SDN was meant to solve

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L3 NEsL0/1 NEs

Monolithic SDN architecture

Monolithic SDN controller

ML App

31

• More concerns:• Optical feasibility “must” be

computed by the optical vendor

• Simulation of IP layer behavior “must” be computed by a tool that understands its complexity

• No single vendor can provide all of this

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L3 NEsL0/1 NEs

Modular Hierarchical SDN architecture

Orchestrator

L3 SDN controller

L3 NEs

L0/1 SDN controller

L0/1 NEs

ML App

32

• Modular approach:• Specialized SDN controller for

each layer• Separate SDN orchestrator

which relies on single layer controllers for single layer services

• More open and flexible solution

• Leaves room for vendor expertise and innovation

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Modular Hierarchical SDN architecture

Orchestrator

L3 SDN controller

L3 NEs

Vendor 2 controller

Vendor 2 NEs

ML App

33

• In fact, in some layers (E.g., DWDM), a controller per vendoris likely• We have failed to

agree on a common way to model transmission impairments

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Vendor 1 controller

Vendor 1 NEs

Outline

• What is SDN? What is ML control about?

• When is central control necessary?

• Different forms of control distribution

• Experimental validation

Tu.1.6.5, SDN/NFV, ECOC 2015

Transport SDN/NFV architecture

35

Dat

ace

nte

r

OpenDayLight#1

OVS

…

Cloud Controller(Distributed Data-centers)

SDN IT and Network Orchestrator (SINO)

Multi-domain Network Hypervisor

…Customer #1

OpenDaylight

NFV Orchestrator

OpenDayLight VNF Manager

Customer #NFloodLight

ONOS VNF Manager…

ONOS#N

GMPLS Controller

Packet Core

Switches

GMPLS Controller

GMPLS Controller

Packet Transport Network

Active StatefulPCE

Multi-domain SDN Orchestrator

Optical Transport Network

Experimental demos at Telefonica’s lab

SDN Solutions showcase (S3), as part of ONS, Santa Clara, CA 5/2015

Experimental demos at Telefonica’s lab

SDN Solutions showcase (S3), as part of ONS, Santa Clara, CA 5/2015

Experimental demos at Telefonica’s lab

• Multi-domain provisioning (3/15)

• Multi-layer optimization (3/15)

• Discovery of cross-layer links (5/15)

• Multi-layer provisioning (10/15)

• Sharing L0 SRLGs with L3 (10/15)

• Coordinated maintenance (10/15)

Optical IP

Vendor X

This project is fundedby the European Union

ACINO: Application-Centric IP/Optical Network Orchestration

645127 – ACINO - H2020-ICT-2014-1

www.acino.eu

Application-aware transport layer

App specific requirements

Grooming layer

Application layer

Low bandwidth

Medium / High bandwidth

App-class requirements

Summary

• Both distributed and centralized control systems have valuable attributes for network control

• It is possible to keep some functions distributed while centralizing others

• Multi-vendor systems are likely to be more distributed to allow for vendor innovation

• Typical network control is likely to be hybrid for the above reasons

Thank you!

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