optical transport technologies for data center interconnections (dci)

Dion Leung, [email protected]

Optical Transport Technologies for Data Center Interconnections (DCI)

AusNOG 10, Sydney, Sept 2, 2016

Topics

•  Fundamental Building Blocks of DWDM Links

•  Key Elements for Flexible and Scalable DWDM Networks

•  New Optical Trends for Data Center Interconnected Networks

2 © 2016 Coriant. All rights reserved. Company Confidential.

Interconnections “Within” a DC

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•  Between racks on the same floor and/or different floors

–  X-connection has been one of the main revenue streams for colocation providers

–  For telco and content providers, x-connections monthly cost can be a big part of the OPEX, especially in carrier-dense, expensive DCs

–  Low cost DWDM point to point solutions have been deployed to reduce monthly recurring cost

–  There is also application to use WDM to connect large-scale switches in spine-and-leaf architecture within ‘hyperscale’ DCs

© 2016 Coriant. All rights reserved. Company Confidential.

Basic DWDM Point-to-Point

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M U X

Individually Colored Wavelengths

D E M U X

Fiber Pair (or Single Core)


Equally spaced channels (aka standard ITU grid)


Basic Power Link Budget Calculation

•  Optical light transmitted through fiber will lose power •  Attenuation caused by Scattering, Absorption and Stress •  Other related parameter: fiber length, fiber type, transmission bands, and external loss

components such as connectors, splices and other passive components •  Typical fiber loss: 0.20 dB/km – 0.35 dB/km, although in some regions fiber loss can be

as high as ~0.5 dB/km •  Basic Power Link Budget Calculation:

Fiber loss + connector loss + multiplexer loss + safety margin ≤ Power Budget (i.e. Transmit – Receive Power on the transceiver)


Elements for DWDM Point-to-Point Connection

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M U X


D E M U X

Fiber Pair (or Single Core)


Equally spaced channels (aka standard ITU grid) Transponders in a “Pizza Box”

Various types of Multiplexer / Demultiplexer

Amplifier in a “xFP” pluggable


Miniaturization: EDFA Technology Example MSA / Module Based à XFP / Pluggable Based

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EDFA: MSA (90x70mm2) EDFA: Ultra-Mini (60x40mm2)

EDFA: XFP & OFP2


XFP-EDFA

Additional Optical Layer Functions to be “Pluggable”


Topics



•  New Optical Trends for Data Center Interconnected Networks


Metro and Regional Interconnection “Between” DCs

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•  Between two or more DCs –  Colocation providers need high-speed

connectivity to make their tenants feel like all cross-connections are “virtually” made in the same DC

–  Dark fiber providers want to expand their business from sell “dark” fiber to “grey” fiber, and from “grey” fiber to wavelength services

–  Content providers decide to spend money from leasing capacity to building their own DWDM network to reduce the transmission cost and TCO over a defined period Graphic credits – please see footnote

1 2

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For Multi-point, Ring and Mesh Fiber Networks…

•  Initially point to point links are deployed between DCs •  The challenge arises when some of the wavelengths are needed to be dropped at DC2

while the rest of the wavelengths will need to be “expressed through” DC2 •  Cost of terminating the wavelengths at DC2 = regeneration with transponders = $$$ per λ

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DC1 DC3 40km

10dB

DC2

20km

6dB

10G or 100G wavelengths




Challenge of Partial Add/Drop Traffic…

DE

MU

X

MU

X

λ λ

λ

λ

λ

λ

λ

λ

λ λ

1. The insertion loss affects the overall link budget

2. Each wavelength added needs to be re-balanced

λ 3. Regeneration is required due to deficit power budget

From DC1 Traffic Add/Drop @ DC2 To DC3


ROADM – Key Element for Building Flexible DC Networks

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A/D Ex2

Ex4

Ex3

ROADM

Fiber Line

A/D

Ex3

Ex2

Ex4

ROADM

Fiber Line

A/D

Ex2

Ex4

Ex3

ROADM

Fiber Line

λ

Mux / Demux

λ

λ A/D

ROADM

Fiber Line

Ex2

Ex3

Ex4

Mux / Demux

λ

λ Express Cable

Automatic Power-Balanced Wavelengths

ROADM becomes an essential technology to enhance the flexibility and scalability of optical networks cost effectively.


Real World Examples of ROADM Networks…


Large-scale DCI networks can be designed cost effectively…

… with latest ROADM technologies, including colorless, directionless, contentionless, gridless functionalities

ROADM Architectures Available for DC-to-DC Interconnection

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Which type of ROADM architecture is right for you? It depends on your application and design objectives.


Metric Individual Modules

ROADM-on-a-Blade

Pluggable Optical Layer

Footprint & Power P PP PPP

Flexibility (to mix & match components) PP P PPP

ROADM Scalability (Degrees, Channels) PPP PPP P

Advanced ROADM Add/Drop (CDC, Gridless) PPP PPP P

Performance/Reach PPP PP P

Ease of Installation PP PPP PP

Cost of Replacing Failed Hardware/Sparing PPP P PPP

Content



•  New Trends for Data Center Interconnected Networks


17 © 2016 Coriant. All rights reserved. Source: IHS/Infonetics: 100G+ and ROADM Strategies, Global Service Provider Survey (Nov. 2015)

DCI Applications Constraints Open Line System Drivers

Cost/port and power density lead but …

… ease of integration and DC automation is key, and…

… requirement for Best-in-Class functions emerging

What are Drivers for Open Line Systems (OLS)?

Open Line System Concept is Gaining Traction

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•  Open Line System (OLS) Model –  Open network decouples “optical layer” from “wavelength service layer” –  Open software interfaces make network management simpler –  SDN applications or customized web portals make automation at the

transport layer possible –  A transponder (wavelength generator) is simply managed as a switch

DWDM ROADM

Open DWDM line system from Vendor B

Vendor C

Vendor A

Open Xponder

DCI Pizza Box

NMS, CLI, NetConf, API

Vendor C

Vendor A

Open Xponder

DCI Pizza Box

DWDM ROADM

DWDM ROADM

Simple Netconf Example on a DCI Pizza Box

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<rpc message-id="101" xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <edit-config xmlns="urn:ietf:params:xml:ns:netconf:base:1.0"> <target> <running/> </target> <config> <ne xmlns="urn:coriant:os:ne"> <shelf> <shelf-id>1</shelf-id> <slot> <slot-id>1</slot-id> <card> <port> <port-id>1</port-id> <och-os> <frequency>192200000</frequency> <laser-enable>enabled</laser-enable> </och-os> </port> </card> </slot> </shelf> </ne> </config> </edit-config> </rpc>

Marching into a New World of Transport Networking…

•  Consideration for Operations –  How does the network operator ensure end-to-end optical performance? –  Who is responsible for support and troubleshooting across domain

boundaries?

•  How “Open” the Physical Transport Layer Will Be? –  How does the industry achieve interop for OLS with different transponder

technologies and suppliers? –  There are new models of disaggregation for the industry to consider

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Innovations Beyond Transmission Level…

•  Improvement of Core Optical Technologies is Essential –  Driving for smaller, faster & lower power modules –  Higher order modulation, tightly integrated packaging and assembly,

volume manufacturing, etc..

•  Operational Innovation –  Embrace a new way of thinking to break incumbency and vendor lock-in,

e.g. Open Line System –  In search for value to be gained from OpEx improvements, not just CapEx

reduction

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Thank You.

Dion Leung on Linkedin or [email protected]

optical transport technologies for data center interconnections (dci)

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