scalable research & education networks dr. brian smith, senior optical systems designer
TRANSCRIPT
Scalable Research & Education NetworksDr. Brian Smith, Senior Optical Systems Designer
Confidential
Content
Introduction.
Review of Requirements for Research and Education Regional Optical Networks.
Comparing Strategies for Regional Optical Networks.
Towards seamless overlay of 10Gbps and 40Gbps traffic.
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Introduction
Regional Optical Networks for Research and Education are being built at an increasing rate Acquisition of dark fiber – lit up as private networks
Some University focused – some joint education/government initiatives.
Large Scale Research Applications are driving the demand for dedicated bandwidth Real time image sharing between collaborating institutions
Very Large Baseline Interferometry
Distributed supercomputer simulations
Interactive Video
Requires a network that can respond quickly to the demands of the Research Community
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What features would be required in such a network ?
Dynamic Provisioning Fully reconfigurable wavelength node
Simple migration from ring to mesh networking.
Ability to switch light-paths using Central/Distributed Management workstation(s).
Single wavelength granularity add and drop.
Seamless switching between DWDM and CWDM providing cost effective multi-grid networks.
Bit rate and protocol transparency – universal interface to higher layers.
Traffic grooming down to ‘STS-1’ level for ultimate flexibility but with GFP for protocol transparency.
= Optimum network configuration matched to actual demand.
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Other Features ?
Simple and Cost-Effective Transport platform that integrates WDM transmission, wavelength
switching and SDH/SONET grooming.
Central or distributed management of all network elements.
Layer 1 performance monitoring at every node – fault isolation.
Auto discovery of nodes, cards and optical interfaces
Interface directly to existing GigE /10GigE routers/switches (carry 10GigE LAN PHY natively without expensive WAN PHY/SONET encapsulation).
Carry any service (Ethernet, SONET, SAN) at wire speed from Fast Ethernet to 10GigE and beyond.
Reduced cost and complexity = Rapid response to new Research Initiatives
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Scalability Add wavelengths ‘in-service’ with no impact on existing traffic.
Add wavelengths with no adjustments to network provisioning (amplifiers etc).
Seamless overlay of wavelengths carrying traffic up to 2.5G, 10G and 40G over the same fiber.
Allow addition of on-grid alien wavelengths.
Make full use of industry standard technologies such as SFP/XFP to reduce cost and complexity of sparing.
All of these features ARE available. . . . .
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Fully Managed via the 8600 NMS & 8300 EMS
7200 OADX
Multi-transport platform Wavelength switching (128 ) STS1 grooming (320G) CWDM, DWDM & ROADM
transmission Transparent & GFP interfaces Mesh, ring, star Scaleable
Meriton Product Family
1450 OFA Line
Pre/post/line EDFA Raman Amplifiers Intelligent controls Transient
suppression 1510nm OSC Up to 600 km links
without regen
1100 DCMs
Fully passive with low insertion loss
Link Extension ProductsMetro Core & Regional
3300 OSU
CWDM & DWDM Transparent & SRM
- Ethernet & SANs- STMx, OCx
Ring, star, & linear 10Gbps supported Seamless interworking
with 7200 OADX
Metro Access
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OADM vs OADXNetwork Issues
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Typical OADM
Transponder-Based
Architecture
Complicates network planning/engineering.- adding a filter affects the whole network.
Serial Filter Design
Prevents interconnection of CWDM to DWDM.Dedicated WDM Transponders
Results in stranded wavelengths around the ring.- all wavelengths in a band are expected to be dropped at the same site
Adding wavelengths requires service outage. - filter insertion, re-cabling, and power re-balancing.
Lack of wavelength switching. - limits networking to point-to-point or ring only.
Lambda Add/Drop Fixed by Band
Can only switch on hard failures eg. fiber cuts.- Cannot switch on data error rate degradation.
Protection Switching Limited to LOS.
Difficult to isolate faults - no electrical loop-backs.
Limited Maintenance & Diagnostic Support.
Cannot monitor layer 1 (protocol level) error rate.- Cannot detect data errors and degradation.
Performance Monitoring Limited to Optical Level.
Truck rolls required to add new service type.- different trib card required per protocol type.
Protocol-specific client-side cards.
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7200 OADX –Unique Product Architecture
Full 3R Regeneration Simplified network design.- Link based design
Wavelength Translation Full CWDM to DWDM connectivity.
Wavelength Switching at the Electrical Level
Non-blocking add/drop of wavelengths.(any wavelength in to any wavelength out). No stranded wavelengths.
Hitless maintenance switches. - of protected lightpaths or cross-connects.
Supports up to 16 WDM network interfaces. - allow support of multiple point-to-point, ring, and mesh networks concurrently.
Performance Monitoringat the Optical and Electrical Level.
Monitoring and detection of layer 1 data errors and degradation. (SONET/SDH, GIGE, FICON, ESCON, Fiber Channel)
Protection switching on data error threshold.- protection on loss of signal or error threshold detect
Supports Multiple Loopbacks
at the Electrical Level.
Simplified network troubleshooting.
ElectronicROADM
Architecture
Same trib card supports multiple service types.- simplified sparing, pay as you grow upgrade - SFPs
Universal client-side cards.
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OADM vs OADXMulti-Degree Support
EastWest
Typical OADM Meriton 7200 OADX
EastWest
2 WDM Network Interfaces Maximum 16 WDM Network Interfaces
Single point-to-point, or single ring network only
Multiple point-to-point, multiple ring, multiple mesh network configurations concurrently.
Shared network – Not dedicated
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OADM vs OADXMulti-WDM Interface Support
Typical OADM Meriton 7200 OADX
DWDM DWDM
CWDM CWDM
DWDM
DWDM
DWDM DWDM
CWDM
CWDM
CWDM CWDM
CWDM DWDM
DWDM CWDM
EastWest
DWDM DWDM
OR
EastWest
CWDM CWDM
EastWestCWDM DWDM
DWDM
CWDM
AND
AND
AND
DWDM
CWDM DWDM
DWDM
DWDM
CWDMCWDM
CWDM
WDM network interfaces must match.Any combination of WDM network interfaces.
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High error rate initiated protection switching is NOT supported by OADMs. - no level 1 performance monitoring to detect data errors
OADM vs OADX High Error Rate Protection Switching
DWDM
DWDMCWDM
Fiber Kink
Layer 1 performance
monitoring detects high error rate and initiates protection switch.
Layer 1 performance
monitoring detects high error rate and initiates protection switch.
OADX layer 1 performance monitoring is used to detect high error rates and automatically trigger protection switching.
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OADM vs OADXAdding Wavelengths
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Typical OADM capacity upgrade
OADM solutions address fiber exhaust needs but introduce difficult operational and engineering constraints
Serial Architecture Filter Design (Cascaded & Banded) Result in Stranded Bandwidth
Serious Scaling Pains w/Re-engineering Required
O
pti
cal P
ow
er
Output w/No Balancing
Maximum Power
OEO OEO OEO OEO Filter Loss = L
4L
DWDM NE
3L2LL
1 2 43
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7200 OADX capacity upgrade
1 DWDM
Mux
DWDM band
Op
tica
l Po
wer
Output w/No Balancing
1 DWDM
1 DWDM
• No power balancing or equalization required when adding wavelengths.
• No re-engineering required simply plug in card / SFP / XFP and your up and running
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7200 OADX
Capacity Upgrade – Line Amplifiers
OADM
Re-provision optical amplifiers to maintain link-budget
1450 OFA amplifiers use gain control – More Gain – No Pain!
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OADM vs OADXAdding New Nodes
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Existing operational network and serviceNeed to add an additional service, including inserting a new POP/node here.“Bridge” the existing service on-the-fly: using existing capacity, point, click, up and running in seconds.
“Roll” the existing connection: hitlessly swing the service to the new path, with no service outage.
Break the fibre. No service outages!Bring the new Meriton node into service, into the existing network. No service outages!
Establish connections to the new equipment. Provision and activate a new light path.
“Roll” the existing service back to its original route.
OADM vs OADX – Network Changes
Bridge and roll is NOT supported by OADMs.- all switch operations result in service disruptions
7200 OADX bridge-and-roll provides hitless maintenance operations.
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OADM vs OADXMulti-Protocols Trib Card Support
Typical OADM Meriton 7200 OADX
• Single Tributary Interface Card.• Multiple Protocols Require Multiple Cards
• More Costly and Complex Upgrades• Any port – Any Protocol.
• Universal Pluggable SFP/XFP Interface
SONET OC-12 SONET OC-48
SDH STM-1 SDH STM-4
GigE
• More expensive Sparing
• Cost Effective Sparing
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Meriton 7200 OADX vs OADM
Functionality Meriton 7200 OADX Typical OADM
Switching Integrated? Yes No
Ring Support? Simplified Engineering Complex Engineering
Mesh Support? Yes No
Mix CWDM & DWDM? Yes No
Wavelength Translation? Yes No
Layer 1 Performance Monitoring?
Yes No
Hitless Maintenance Yes No; requires services outages
Scalability Yes, cost-effective Difficult and expensive
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Overlaying 10G and 40G traffic on existing
networks
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Link Engineering- Challenges
10GOTR
2.5G DWDM
DCMOFA
Mux
2.5G DWDM
40G
Need to understand dispersion tolerance and PMD tolerance to overlay 10G
DCMOFA
Dispersion tolerance and PMD are much more of an issue when overlaying 40G traffic
DCMOFA
Lets have a quick look at these issues . . .
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Dispersion Tolerance
The dispersion experienced over any km of fiber segment lies within a range defined by the manufacturer.
Wavelength (nm)
Co
mp
ensa
tio
n (
ps
/nm
)
Similarly, the amount of compensation delivered by a typical DCM is only accurately known within a range.
Wavelength (nm)
Dis
per
sio
n (
ps/
nm
km)
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Dispersion Tolerance (cont. .)
Taking a 6 span x 80km link with each span compensated 100%, the actual net dispersion can lie between –500 and +500 ps/nm !
0
0.02
0.04
0.06
0.08
0.1
0.12
0.14
-600 -400 -200 0 200 400 600
Net Dispersion (ps/nm)
Pro
b (
au)
So how would this large range in net dispersion affect the eye closure penalty for 2.5, 10 and 40G traffic ?
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0
1
2
3
4
5
6
7
-600 -400 -200 0 200 400 600
Net Dispersion (ps/nm)
Pen
alty
(d
BQ
)
0
1
2
3
4
5
6
7
-600 -400 -200 0 200 400 600
Net Dispersion (ps/nm)
Pen
alty
(d
BQ
)
-1
0
1
2
3
4
5
6
7
-600 -400 -200 0 200 400 600
Net Dispersion (ps/nm)
Pen
alty
(d
BQ
)
6x80kmx26dB - 32
2.5G
40Gneeds ADCM + enhanced FEC
10Gneeds FEC
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Polarization Mode Dispersion
Using 6x80kmx26dB with 6 EDFA and 6 DCM, the calculated average DGD (assuming fiber is post 1995) = 2.5 ps
The PMD tolerance (and expected outage) for various data rates is:
Rate pmd tolerance system outages/yr
2.5G 30ps insignificant pmd outages/yr
10G 7.6ps insignificant pmd outages/yr
40G(NRZ) 1.9ps ~ 22 minutes/year uncompensated
40G(RZ) 2.7ps ~0.5 seconds/year uncompensated
40G scenarios improved using enhanced FEC and/or PMD compensation.
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10G + 40G overlay on existing traffic
With an appropriate adaptive DCM at the receiver and enhanced FEC, 40G traffic can be transmitted over a system designed to support 2.5 and 10G traffic.
With PMD compensation and/or FEC, a 40G(NRZ) system is capable of reaching ~ 500km with no significant outages resulting from PMD.
A 40G(RZ) system with FEC is capable of reaching ~ 700km with no significant outages resulting from PMD
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Summary
Reviewed some of the requirements for Research and Education Regional Optical Networks.
Compared OADM vs OADX strategies for Regional Optical Networking.
Analyzed the impact of Chromatic Dispersion and PMD tolerance for migration to 40Gbps traffic over existing networks.
