nobel wp5 meeting munich – 14 june 2005 wp5 cost study group author:martin wade (bt) lead:andrew...

NOBEL WP5 MeetingMunich – 14 June 2005

WP5 Cost Study Group

Author: Martin Wade (BT)

Lead: Andrew Lord (BT)

Relative Cost Analysis of Transparent & Opaque Optical Network Design Solutions

2NOBEL WP5 Ipswich Meeting - 18 March 2005BT - Martin Wade

Objectives

Is the transparent optical network cheaper than the “traditional” network, and if yes: what are the boundary conditions?

Analyse the following scenarios:– Fully transparent networks (O/O/O, optical switch matrix, no

transponders for transit traffic and thus no wavelength conversion)

– Traditional opaque networks (O/E/O, electrical switch matrix, point-to-point links only, transponders required for transit traffic)

– Hybrid networks (transparency islands with transponders for signal regeneration and/or wavelength conversion)

– New vendor solutions, e.g. Infinera cheap integrated 10 * 10 Gbit/s O/E/O chips

Understand underlying design and cost factors– Consider ‘pragmatic’ & ‘realistic’ rather than optimised designs


Inputs

Reference networks

– Pan-European, DT, TILAB, BT core & London metro

Traffic demand

– Three traffic growth levels per network

– 10 Gbit/s granularity only

– Traffic assumed to be already groomed• Potential advantage of opaque solution thus not taken into account

• Client layer architectures not considered, although heavy impact on traffic profile

– Unprotected• Protection and shared restoration not yet considered

– Static (once provisioned, it remains for long time)• Dynamic traffic not yet considered

Network element costs

– Capex only considered initially


Methodology

Excel/VBA calculations performed

– No formal modelling tools available for general use

Routing for opaque and transparent designs

– Fixed routing for each individual traffic demand• Adaptive routing not yet applied

– Least cost routing (minimum hop and minimum path distance other options)

Wavelength assignment for transparent design

– ‘First fit’ method applied (lowest numbered spare wavelength used; lowest numbered OMS used for each link)

– Order of traffic assignment options: max hop paths first or random order (simulates incremental provisioning with no foresight)


Node Models

Opaque SwitchLine Cards & Transponders

Opaque SwitchColoured Line Cards

Transparent Switch

O-E-O Transponder (1310/1550nm to ITU grid wavelength conversion)

E-O Line Card (1310/1550nm)

O-E-O Transponder (1310/1550nm to ITU grid wavelength conversion)


E-O Coloured Line Card(ITU grid wavelength)


E-O Coloured Line Card(ITU grid wavelength)


O-E-O Transponder (1310/1550nm to ITU grid wavelength conversion)O-E-O Transponder (1310/1550nm to ITU grid wavelength conversion)


Network Cost Elements

Input from WP2 D15 with additional data from Siemens– Data to be verified

Major items used:– Base unit: Electrical STM-1 line-card 1

– STM-64 LR transponder 160 (too high)

– STM-64 SR line card 70 (only for add/drop)

– 40 channel mux/demux module 220

– 80 channel mux/demux module 500

– Amplifier SH 220

– Signal conditioning element 430 (transparent only)

– Opaque switch per port 18.75(derived)

– Transparent switch per port 12.5 (derived)


High-Level Design Comparisons

Switch port dimensioning

– Transparent & Opaque 2 * Traffic * (Av hops + 1)

Transponder dimensioning

– Transparent 2 * Traffic• Additional for regeneration over transparency limit

– Opaque 2 * Traffic * Av hops• Proportion of transponders for drop traffic 1 / Av hops

• Proportion of transponders for transit traffic 1 – (1 / Av hops)

• May be implemented as:

– line card & transponder

– coloured line card (probably cheaper, but there may be compatibility issues with using different OMS supplier)


High-Level Design Comparisons

Line card dimensioning (Opaque only)

– Tributary line cards 2 * Traffic

– Trunk line cards 2 * Traffic * Av hops

• Only if line cards are used with transponders (see previous slide)

OMS channel dimensioning (per link)

– Opaque No of connections on link

– Transparent Max channel used on link

– Ratio of (max channel / link load) is the Wavelength Continuity Penalty

• Results in more OMS channels required to carry all traffic or fewer routable traffic demands

• Dependent on network topology, OMS channel capacity, order of routing assignment

– Sum of all opaque link loads Traffic * Av Hops


Initial Design Results – Pan-European

16 nodes; 23 links

Key stats

0

500

1000

1500

2000

2500

3000

3500

4000

2005

No

of

Ele

men

ts

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

Traffic Av Hops WCP2005 526 2.5 1.22006 1010 2.5 tbc2007 2166 2.6 tbc

Total Costs (excl. ILAs)

Opaque Transparent2005 0.60 0.282006 1.15 tbc2007 2.49 tbc

* Based on 40 channel OMS systems and traffic provisioned in random order (average of 100 runs)

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

2005

Rel

ativ

e C

ost

Un

its

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *


Initial Design Results - DT

17 nodes; 26 links

Key stats

0

500

1000

1500

2000

2500

3000

3500

2005 2006 2007

No

of

Ele

men

ts

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

0

50000

100000

150000

200000

250000

300000

350000

400000

2005 2006 2007

Rel

ativ

e C

ost

Un

its

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

Traffic Av Hops WCP2005 226 2.4 1.42006 315 2.5 1.42007 478 2.4 1.3


Opaque Transparent2005 0.25 0.132006 0.35 0.172007 0.53 0.26



Initial Design Results - TILAB

38 nodes; 79 links

Key stats

0

500

1000

1500

2000

2500

3000

3500

4000

2005 2007 2009

No

of

Ele

men

ts

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

0

50000

100000

150000

200000

250000

300000

350000

400000

450000

2005 2007 2009

Rel

ativ

e C

ost

Un

its

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

Traffic Av Hops WCP2005 300 3.0 1.92007 357 2.8 2.02009 473 2.6 1.9


Opaque Transparent2005 0.40 0.202007 0.44 0.242009 0.55 0.30



Initial Design Results – BT Core

79 nodes; 139 links

Key stats

0

2000

4000

6000

8000

10000

12000

14000

Base 3x Growth 5x Growth

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

0

200000

400000

600000

800000

1000000

1200000

1400000

1600000

1800000


Rel

ativ

e C

ost

Un

its

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

Traffic Av Hops WCPBase 526 3.9 1.83x Growth 829 4.1 1.55x Growth 1171 4.2 1.4


Opaque TransparentBase 0.87 0.393x Growth 1.45 0.595x Growth 2.05 0.81



Initial Design Results – BT Metro

38 nodes; 62 links

Key stats

0

500

1000

1500

2000

2500

3000


No

of

Ele

men

ts

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

0

50000

100000

150000

200000

250000

300000

350000


Rel

ativ

e C

ost

Un

its

Op. Sw. Ports

Tr. Sw. Ports

Op. Transp.

Tr. Transp.

Op. Line Cards

Tr. Line Cards

Op. OMS Ch.

Tr. OMS Ch. *

Traffic Av Hops WCPBase 193 2.9 1.63x Growth 233 3.0 1.55x Growth 297 3.1 1.5


Opaque TransparentBase 0.25 0.123x Growth 0.31 0.145x Growth 0.40 0.19



Initial Conclusions

As suspected, costs of transponders in opaque designs far outweigh additional OMS costs in transparent designs

– Opaque designs 1.9 – 2.5 times more expensive than equivalent transparent designs

However, transponder costs are clearly far too high in current cost model

– Effect of Infinera cheap integrated 10 * 10 Gbit/s O/E/O chips also to be determined, e.g. what fraction would they have to be to cost in?

Effect of loading traffic in random order compared to near-optimal heuristic ranges from 2% to 40% additional OMS channels required

Smaller OMS system capacities significantly reduce the additional OMS channels required - up to 88% more if there is no OMS capacity limit - due to effective wavelength conversion with multiple stacked OMS systems on same link


Further Work

Cost sensitivity analysis

Adaptive (state-dependent) routing

Traffic protection and shared restoration

Trade-off of transparency limit vs. regenerator costs

– Analysed by Matthias for DT network

– Transparency limit (1500 km) currently so high very few traffic paths exceed limit

– Will allow transparency islands to be analysed

Opex considerations

– Reliability of components

– Operation of network

nobel wp5 meeting munich – 14 june 2005 wp5 cost study group author:martin wade (bt) lead:andrew...

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