building an optical regional flexible transmission platform · flexible transmission platform ......

Building an Optical Regional Flexible Transmission Platform

Anthony RyanTim Robinson 09-Apr-2008


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NNW Flexible Transmission Platform•

Getting Hold of the Fibre

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Scenario 1 Research sites CWDM•

Scenario 2 Local Data Centres CWDM

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Scenario 3 Adding DWDM•

Summary

NNW Flexible Transmission Platform

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Part of NNW SJ5 Exploitation Plan•

Build e-Science Network

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Replace Telco GigE links with Dark Fibre•

Telco costs go down (no equipment) with move from GigE to Dark Fibre but costs tend to go up

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Dark fibre is still much cheaper than multiple GigE or 10 Gbps links

Who was asking for all these new links and extra bandwidth ?•

driven by e-science projects

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separation from production traffic•

dedicated bandwidth across the region

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usually to reach a UKLight or JLPS circuit at Manchester (JANET entry point for NNW)

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or part of a regional research network•

or just “free”

bandwidth across a campus

WDM ?•

different λ

simultaneously on same fibre

-

optical signals from separate devices are assigned to different specific wavelengths.-

the specific wavelengths are multiplexed

together and injected into a single shared fibre.

CWDM v DWDM•

CWDM–

large channel spacing

–

less channels but cheaper components–

lasers don’t need cooling

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filters can be less accurate •

DWDM–

channels crammed tighter -

more channels

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more expensive filters, lasers


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Summary


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G-MING used dark fibre since 1995•

NNW has had short range dark fibre since 1997

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Discussions with Telcos since 2005 about long distance dark fibre–

THUS

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NTL:Telewest•

Telcos understand what NNW is trying to achieve and why


Major Problems•

Diverse Routing

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Distances

Spring 2008 -

Schematic

Summer 2008 -

Schematic


Major Problems•

Diverse Routing

•

Distances

Summer 2008


Major Problems•

Diverse Routing

•

Distances


Major Problems•

Diverse Routing

•

Distances

Manchester –

Liverpool•

Point to point

48 km

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On fibre

101 km


Major Problems•

Diverse Routing

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Distances

Preston –

Liverpool•

Point to point

44 km

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On fibre

126 km


Major Problems•

Diverse Routing

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Distances

Manchester –

Jodrell•

Point to point

26 km

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On fibre

79 km

Lighting the Fibre

Use Transmode CWDM and DWDM equipment

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Transmode were keen to come and do trials

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And to do a demo of the kit •

and offer sale or return


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Summary

First Scenario: Jodrell Bank Observatory

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eVLBI -

a lot of telescope data to shift •

already had a 155 Mbps link for production

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needed extra capacity•

they obtained some new SM dark fibre (one pair) from Global Crossing

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wanted to get 2 x 1 GbE links out of it •

maybe more later

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this was a pretty simple arrangement


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we didn’t even need an optical mux•

just plugged the fibre directly into the LINE (WAN) interface of a card at each site –

operating at 1510nm

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hence no mux needed because 1510nm was the only wavelength on the line

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linecards convert this and present it as 850nm•

presented to end systems as multimode


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Jodrell Bank link required cards which could drive 80 km

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the 80km receivers will work with a signal as low as -28db

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we are receiving at about -26 db •

pretty close to lower limit but it worked without any problem

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JBO could begin to test sharing data…•

we implemented a similar arrangement on the Daresbury-Manchester and Daresbury to Liverpool links


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Summary

Second Scenario Linking Two Data Centres

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requirement for GigE and fibrechannel •

had some SM dark fibre locally between two datacentres

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talked to Transmode again•

they asked about the fibre we had

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gave us a few choices•

explained some future possibilities


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so we came to initial design•

Transmode TS 1100 chassis with flexible choices of CWDM card combinations

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links could be set as GbE or Fibrechannel•

up to 16 wavelengths –

we use 6 of them

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an optical multiplexor to split up and recombine the CWDM wavelengths


•simple enough –

no amplifiers needed•modules arrived set to appropriate assortment of wavelengths•just put the appropriate modules in each card•then connect each card to the matching port on the optical mux


•nothing to configure on some cards•other cards you just set the protocol eg fibrechannel, GbE or STM•each card then spits out normal 850nm towards your end devices•so we got 5 fibrechannel links and 2 x 1 GbE across a single pair•it pretty much worked out of the box –

no tuning or configuration


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Even the lowest spec card drives up to 40 km so 2km was easily covered

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2 km of fibre plus a couple of patches provides enough attenuation

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The 40km receivers will work with a signal as low as -20db or as high a 0db

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We are receiving at about -6db so no problem – it just works

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We have spare capacity to use the extra channels –

just add extra cards


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Summary

Third Scenario Adding DWDM for 10 gig

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We had used the same simple CWDM arrangement for Daresbury and Jodrell Bank i.e. we had provided 2x1GbE using simple CWDM-

DL: one for production/one for a regional

(North West Grid project) to Manchester and to Liverpool-

JB: two for research telescope data

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Two extra requirements came up…


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JANET(UK): “we can deliver 10 gig from Frankfurt to Manchester…can you deliver it to Daresbury ?”

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JANET(UK): “we can deliver 4 gig from Onsala to Manchester…can you drop that off in Jodrell Bank ?”

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So we explored how to get 10 gig across our existing links


DWDM C-band

CWDMOutsideDWDM-band

Mixing DWDM and CWDM Wavelengths

You can mix the two - as long as you leave some space!

In our case we had been advised to avoid 1550nm for CWDM since that covers the C-band which is a popular choice for DWDM. This made things easier when we came to add DWDM

But there are alternative combinations (of CWDM and DWDM bands)……as long as you have left appropriate space somewhere

CWDM OutsideDWDM-band

1 2 45 6 7 8


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got a bit more interesting as we got into mixing CWDM and DWDM on same fibre

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needed Amplifiers, Dispersion Control, OADM•

ended up with two sets of chassis

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added some extra gig links with CWDM too


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the add/drop multiplexer is the thing which lets you mix CWDM/DWDM wavelengths

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it strips off certain wavelengths for you•

lets you pass those to your CWDM cards

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and passes everything else to your DWDM kit


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What all this kit does…


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Normal signal arrives, say, at 850nm


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Signal gets converted to a specific DWDM wavelength

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1550.12nm in our case


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This filter combines DWDM wavelengths•

We only use one at the moment


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Our single DWDM wavelength carries on


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Signals get amplified for their journey •

The optimum level depends on how many channels you see yourself using in future


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DWDM signals mixed with CWDM here•

Note we only had to amplify the DWDM


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Signals travel across link•

Power will be dropping on the way


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Add/drop multiplexer does its job•

Peels off our specific CWDM wavelengths


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We needed amplifiers before and after the long distance links


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We also needed dispersion control modules due to the long distance


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If we used more than one DWDM wavelength they would be split up by this filter


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Reaches the receiver –

hopefully at a nice comfortable level after being amplified twice while suffering attenuation on way


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Signal presented to end systems


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Summary

NNW e-Science Network

ManchesterKilburnDaresbury Daresbury

Liverpool

2 * 1 Gbps 2 * 1 Gbps2 * 1 Gbps

1 Gbps

1 * 10 Gbps

Jodrell

ManchesterReynolds

1 * 10 Gbps

4 * 1 Gbps

Summary

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If using CWDM, try to keep some space in case you choose to add DWDM later

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Most common for DWDM is C-band but there are S or L bands you could reserve instead

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Keep telco fibre records –

helps at design•

find out how your UKLIGHT circuits are to be presented –

avoid unnecessary LH/SH type

media conversion•

Need optical meters to commission and test

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New hardware maintenance requirement

Futures•

Procurement of kit for production network

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N * 10 Gbps on NNW ‘diamond’•

Liverpool –

Preston –

Manchester –

Stoke

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Liverpool•

N=2, 4?

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Use MPLS instead of n * 1 Gbps for lower speed links?

NNW e-Science Network

ManchesterKilburnDaresbury Daresbury

Jodrell

2 * 10 Gbps

2 * 10 Gbps

2 * 10 Gbps

2 * 10 GbpsLiverpool ManchesterReynolds

2 * 10 Gbps

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