[2] M. Born and E. Wolf. Principles of Optics: Electromagnetic Theory of Propagation, Diffraction and Interference of Light.

(1)

198

CONCLUSIONS

The activities which have originated this book have been an interesting opportunity to learn in detail many fiber optic and optical networks features.

Our final goal – totally reached – was to implement an optical core with 3 PMA32s, providing 32 optical channels with a 2,5 Gbps capacity, each with its protection line in case of failure/fault. This core can be used as a linear network or as an optical ring, depending on the necessities – and this can be obtained simply using the software by Marconi-Ericsson in remote mode, thus avoiding manual maintenance.

The infrastructure we built up is an optical ring between the Information Engineering Dept. and the national CNR, throughout the city of Pisa. The same kind of network can be created using as many PMA32s as necessary, in any metro or regional area, thus originating metro-access or long-haul infrastructures.

To test the optical core we configured the needed cross-connections and pass-through connections and we measured some performance parameters by a Spirent AX4000 traffic generator/analyzer. Different kinds of simulated traffic have highlighted a good performance of a 2 PMA32 core, and have generated a medium packet transfer delay of 122.8 microseconds, due to the entire optical network. Only a latency of 1 microsecond is due to a single PMA32, thus indicating that it’s a very good OADM for all-optical infrastructures.

As for the protection paths, we have tested every possible configuration of the ring and every possible failure of a TX/RX component: in every single case the PMA32 immediately reconfigures the network forcing the traffic sent to the line which is properly working, and the loss of packets is very low and not significant.

Along the ring many different configurations are possible, and each logical configuration generates a different latency, according to the physical configuration. So the traffic analyzer also becomes an efficient way to measure the relative lengths of the deployed fiber cables, thus choosing the shortest path with the smallest packet transfer delay. In our case 3 possible paths are possible between the two ends of the city of Pisa: we got delays of 104.5, 122.9 and 141.2 microseconds. In case of failure or necessity to change the logical topology of the network the delay stays more or less the same.

When a card doesn’t work properly, it can be difficult to understand from where the alarms are originated because the PMA32 has a complex and maybe too precise fault management system;

anyway we tried to trace a good guide to concrete alarms and solutions in this book.

Sending video traffic on the implemented optical ring was maybe the most immediate and practical way to see if the PMA32 is able to carry parallel flows in an efficient way and to keep on transmitting on a ring when there’s a fault on the working line: the protection mechanism behaved the way it was supposed to.

Grid computing and its topology discovery service are a second interesting example treated in this book which allowed to see once more that the PMA32 can be a good component for DWDM optical cores.

The final chapter about the Ericsson’s products in the backbone networks’ scenario is a last series of considerations on the future objectives of optical technology. The new backbones are now and will always being reconfigured to encounter the growing demand for bandwidth, so they are becoming mesh-shaped, more complex, and layered with a standard IP/MPLS over OTN/ASON.

Many different possibilities are being tested and projected. Only future will give the final answers.

(2)

199

REFERENCES

[1] J.A. Buck. Fundamentals of Optical Fibers. John Wiley, New York, 1995.

[2] M. Born and E. Wolf. Principles of Optics: Electromagnetic Theory of Propagation, Diffraction and Interference of Light.

Cambridge University Press, 1999.

[3] L.G. Kazovsky, S. Benedetto, and A. E. Willner.

Optical Fiber Communication Systems. Artech House, Boston, 1996.

[4] C. Lin, editor. Optoelectronic Technology and Lightwave

Communications Systems. Van Nostrand Reinhold, New York, 1989.

[5] M.W. Chbat et al. Towards wide-scale all-optical networking:

The ACTS optical pan-European network (OPEN) project. IEEE JSAC.

Special Issue on High-Capacity Optical Transport Networks, 16(7):1226-1244, Sept. 1998.

[6] G.P. Agrawal and N. K. Dutta. Semiconductor Lasers.

Kluwer Academic Press, Boston, 1993.

[7] M. Born and E. Wolf. Principles of Optics: Electromagnetic Theory of Propagation,Diffraction and Interference of Light.

Cambridge University Press, 1999.

[8] D. Chiaroni et al. New 10 Gb/s 3R NRZ optical regenerative interface based on semiconductor optical amplifiers for all-optical networks.

In Proceedings of European Conference on Optical Communication, pages 41-43, 1997.

[9] R. Perlman. Interconnections: Bridges, Routers, Switches, and Internetworking Protocols.

Addison-Wesley, Reading, MA, 1999.

[10] E. Desurvire. Erbium-Doped Fiber Amplifiers:

Principles and Applications. John Wiley, New York, 1994.

(3)

200

[11] L.A. Coldren. Monolithic tunable diode lasers. IEEE Journal of

Selected Topics in Quantum Electronics, 6(6):988-999, Nov./Dec. 2000.

[12] M. Sexton and A. Reid. Broadband Networking:

ATM, SDH and SONET. Artech House, Boston, 1997.

[13] J. Walrand and P. Varaiya.

High-Performance Communication Networks.

Morgan Kaufmann, San Francisco, 2000.

[14] T.L. Koch and U. Koren. Semiconductor lasers for coherent optical fiber communications. IEEE/OSA Journal on Lightwave Technology, 8(3):274-293, 1990.

[15] S. Aidarus and T. Plevyak, editors. Telecommunications Network Management into the 21st Century.

IEEE Press, Los Alamitos, CA, 1994.

[16] M.-C. Amann and J. Buus. Tunable Laser Diodes. Artech House, Boston, 1998.

[17] P.E. Green. Fiber-Optic Networks. Prentice Hall, Englewood Cliffs, NJ, 1993.

[18] G.P. Agrawal. Fiber-Optic Communication Systems.

John Wiley, New York, 1997.

[19] G.N.S. Prasanna, E. A. Caridi, and R. M. Krishnaswamy.

Metropolitan IP-optical networks: A systematic case study.

In Proceedings of National Fiber Optic Engineers Conference, 2000.

[20] C. Clos. A study of nonblocking switching networks.

Bell System Technical Journal, 32:406-424, March 1953.

[21] Broadnets 2007 Invited Paper:

Topology Discovery and Performance Information Services for Optical Grids by Valcarenghi, Paolucci, Castoldi, Cugini, Adami, Ficara, Giordano

[22] L. Valcarenghi, L. Foschini, F. Paolucci, F. Cugini, and P. Castoldi,

“Topology discovery services for monitoring the global grid,” IEEE

Communications Magazine, vol. 44, no. 3, pp. 110–117, March 2006.

(4)

201

LIST OF FIGURES

Chapter 1

Figure 1.1 – Principle of Total Internal Reflection 2

Figure 1.2 – Attenuation loss in silica as a function of wavelength 3 Figure 1.3 – The three bands, S-band, C-band, and L-band, based on amplifier availability, within the low-loss region around 1.55 µm in silica fiber 4

Figure 1.4 – Optical coupler scheme 5

Figure 1.5 – Star coupler 6

Figure 1.6 – Three-port (a) and four-port (b) optical Circulators 7 Figure 1.7 – Different applications for optical filters in optical networks 8

Figure 1.8 – A static wavelength cross-connect 8

Figure 1.9 – (a) A transmission grating and (b) a reflection grating 9

Figure 1.10 – A lens and the obtained wavelength 10

Figure 1.11 – Example of Serial Architecture DEMUX 11

Figure 1.12 – Example of Single-Stage Architecture DEMUX 11

Figure 1.13 – Multistage Banding Architecture DEMUX 12

Figure 1.14 – Multistage Interleaving Architecture DEMUX 13

Figure 1.15 – EDFA architecture 14

Figure 1.16 – Block diagram of a receiver in optical communications 16

Figure 1.17 – Crossbar switch 18

Figure 1.18 – 1024 • 1024 switch using 32 x 64 and 32 x 32 switches interconnected in a

three-stage Clos architecture 18

Figure 1.19 – A 2D mirror 19

Figure 1.20 – A 3D mirror 19

Figure 1.21 – Example of wavelength converter 20

Figure 1.22 – Wavelength grid selected by the ITU 22

(5)

202

Figure 1.23 – IP in the layered hierarchy 24

Figure 1.24 – Various implementations of IP over WDM 24

Figure 1.25 – A wavelength-routing mesh network showing optical line terminals (OLTs), optical add/drop multiplexers (OADMs), and optical crossconnects (OXCs).

The network provides light-paths to its users, such as SONET boxes

and IP routers 25

Figure 1.26 – Block diagram of an optical line terminal 27

Figure 1.27 – A three-node linear network example to illustrate the role of optical add/drop multiplexers.

(a) A solution using point-to-point WDM systems.

(b) A solution using an optical add/drop multiplexer at node B 28 Figure 1.28 – Different OADM architectures. (a) Parallel, where all the wavelengths are

separated and multiplexed back; (b) modular version of the parallel architecture; (c) serial, where wavelengths are dropped and added one at a time; and (d) band drop, where a band of wavelengths are dropped and

added together 30

Figure 1.29 – Using an OXC in the network 32

Figure 1.30 – Forward and backward defect indicator signals and their use in a network 34 Figure 1.31 – The optical supervisory channel, which is terminated at each amplifier 35 Figure 1.32 – A typical carrier backbone network based on SONET/SDH 36

Figure 1.33 – Architecture of a typical backbone node 36

Figure 1.34 – Architecture of the future telecommunication networks 38

Figure 1.35 – Wavelength regions 38

Figure 1.36 – Evolution of DWDM 39

Figure 1.37 – DWDM Functional Schematic 40

Figure 1.38 – Mux/Demux functions with a Prism 40

Figure 1.39 – Mux/Demux functions with a Grating 41

Figure 1.40 – End-to-end anatomy of a DWDM System 41

Chapter 2

Figure 2.1 – A view on the mechanical apparatus in the PMA-32 45

Figure 2.2 – An example of PMA-based architecture 46

(6)

203

Figure 2.3 – Internal traffic architecture of a PMA-32 47

Figure 2.4 – West TX line detailed view 48

Figure 2.5 – East RX line detailed view 48

Figure 2.6 – Internal traffic interfaces 49

Figure 2.7 – Example of multiple alarms on a PMA32 53

Figure 2.8 – Local Craft Terminal (LCT), the Marconi software provided with the PMA32 59

Chapter 3

Figure 3.1 – NE Source’s LINE WEST showing our 192.80 tributary 61 Figure 3.2 – LINE EAST, showing the 192.80 frequency again 61 Figure 3.3 – How to have access to other PMA’s in Remote Mode 62 Figure 3.4 – The configured transponders on the 2^nd PMA, shown in Remote Mode 62 Figure 3.5 - First step for the cross-connection: selection of the 192.80 frequency

up to the West RX terminal 63

Figure 3.6 – Selecting the Creation of the Cross-connection 64

Figure 3.7 – The Cross-connection has been created 64

Figure 3.8 – First step to create SNC protection 65

Figure 3.9 – Default values for the activation of SNC protection 65

Figure 3.10 – Protection has been activated 66

Figure 3.11 – Result of the procedure: 192.60 and 192.80 tributaries have their protected cross-connections (indicated with “Bidirectional” and “Intra Card”) 66

Figure 3.12 – First step to activate a pass-through 67

Figure 3.13 – Creation of the desired pass-through 68

Figure 3.14 – Frequency 193.10 has been configured as a pass-through 68 Figure 3.15 – First step to UNCONFIGURE T5 and T7 transponders 69

Figure 3.16 – DELETE SNC PROTECTION option for the T7 70

Figure 3.17 – DELETE CROSS-CONNECTION option, still on the T7 70

Figure 3.18 – MODIFY CABLE option 71

(7)

204 Figure 3.19 – Actual ADJACENT CABLE ROUTING choice in MODIFY CABLE window 72

Figure 3.20 – Final NO CABLE ROUTING choice 72

Figure 3.21 – T5,6,7,8 slots are now with no frequency indicated 73 Figure 3.22 – Adjacent Cable Routing for the new slots we need for our cards 73

Figure 3.23 – ADOPT function 74

Figure 3.24 – Port Configuration for the added payload type 74

Figure 3.25 – Gigabit Ethernet payload type 75

Figure 3.26 – How to activate the ANALOGUE MONITOR function 76

Figure 3.27 – ALARMS obtained using a single PMA 77

Figure 3.28 – ALARMS obtained in the point-to-point link 77

Figure 3.29 – TX section @ PMA not connected to the AX4000 78 Figure 3.30 – RX section @ PMA not connected to the AX4000 79 Figure 3.31 – Tributary 192.80 @ PMA not connected to the AX4000 79 Figure 3.32 – Tributary 192.80 @ PMA connected to the AX4000 80 Figure 3.33 – Packet Transfer Delay obtained on a single PMA with 1500 byte IP packets 81 Figure 3.34 – Histogram showing the packet transfer delay more precisely 81 Figure 3.35 – TX section @ PMA connected to the AX4000 sending traffic 82 Figure 3.36 – RX section @ PMA connected to the AX4000 sending traffic 82 Figure 3.37 – Tributary 192.80 @ PMA connected to the AX4000 sending traffic 82 Figure 3.38 – PMA A1 (Information Engineering Department) – Analogue Monitor

Display about Tributary 192.80 84

Figure 3.39 – PMA A3 (CNIT) – Analogue Monitor Display about Tributary 192.80 84 Figure 3.40 – PMA A3 (CNIT) – Analogue Monitor Display about Tributary 193.10

(not available in the A1 PMA) 85

Figure 3.41 – PMA A1 (Information Engineering Department) – Analogue Monitor Display

about Tributary 192.80 85

Figure 3.42 – PMA A3 (CNIT) – Analogue Monitor Display about Tributary 192.80 86 Figure 3.43 – PMA A3 (CNIT) – Analogue Monitor Display about Tributary 193.10

(not available in the PMA A1) 86

(8)

205

Figure 3.44 – TX LINE WEST 87

Figure 3.45 – TX LINE EAST 87

Figure 3.46 – RX LINE WEST 88

Figure 3.47 – RX LINE EAST 88

Figure 3.48 – Final Resume of the values obtained for the PMA-32’s transponders

with all the tests 89

Figure 3.49 – Final Resume of the values obtained for the PMA-32’s TX & RX Lines 90 Figure 3.50 – The different fixed datagram lengths we use for our test 94 Figure 3.51 – Selection of the desired traffic in the AX4000 Generator 95

Figure 3.52 – 64byte packets; 50% 95

Figure 3.53 – 64 byte packets; 80% 96

Figure 3.55 a b c d – Packet transfer delay histograms obtained with increasing

% bandwidth values 97

Figures 3.69 a b c – Histograms obtained with 1500 bytes packets –

50%,80%,100% bandwidth 104

(9)

206

Figure 3.70 – Packet Transfer Delay due to the AX4000 105

Figure 3.71 – Amend SNC Protection window 107

Figure 3.72 – A3 PMA equipment 111

Figure 3.73 – A2 PMA equipment 111

Figure 3.74 – Router-Tester window with the two simulations of traffic 112 Figure 3.75 – Amend SNC Protection window when the worker channel is LINE EAST 113 Figure 3.76 – Amend SNC protection window in case of fail on TX WEST 114 Figure 3.77 – Amend SNC protection window in case of fail on RX East 114 Figure 3.78 – No more fail on RX East – NON REVERTIVE mode 115

Figure 3.79 – No more fail on RX East – REVERTIVE MODE 115

Figure 3.80 – Amend SNC protection window in case of fail on TX East 116 Figure 3.81 – Amend SNC protection window in case of fail on RX West 117 Figure 3.82 – Swap Worker/Protection option on 193.10 frequency 117 Figure 3.83 – Router-tester analysis when simulating a signal fail on the ring 118 Figure 3.84 - Router-tester analysis during the transition between signal fail and ring

working again 119

Figure 3.85 – Signal fail on protection indication in the present configuration of the ring 119 Figure 3.86 – Table resuming the values measured in the preceding tests 120

Figure 3.87 – 192.8 and 193.1 ADD/DROP procedure 121

Figure 3.88 – WEST / WEST Ring 122

Figure 3.89 – Alarms for the A1 PMA 123

Figure 3.90 – 193.10 tributary’s Amend SNC Protection window (A1) 124 Figure 3.91 – 192.80 tributary’s Amend SNC Protection window – Dual Ended mode (A1) 124 Figure 3.92 - 192.80 tributary’s Amend SNC Protection window – Single Ended mode (A1) 125

Figure 3.93 – SQM (Signal Quality Monitor) 125

Figure 3.94 – How to select the SQM Analogue values 126

Figure 3.95 – Changed situation after the elimination of the 192.80 tributary’s protection 126

(10)

207 Figure 3.96 – Alarms for the A3 PMA, at the other end of the link 127 Figure 3.97 – 193.10 tributary’s Amend SNC Protection window (A3) 127 Figure 3.98 - 192.80 tributary’s Amend SNC Protection window – Dual Ended mode (A3) 128 Figure 3.99 – The WEST LOSS OF SIGNAL alarm that shows what is wrong

with the A3 PMA 128

Figure 3.100 – Latency (green), Bandwidth (blue) and Lost packets (red) for the tributaries 129 Figure 3.101 – The way we want the point-to-point link to be (WEST / WEST Ring) 129

Figure 3.102 – The way the point-to-point link is configured by the PMA’s,

in this case of SIGNAL FAIL - DUAL ENDED MODE 130 Figure 3.103 – The way the link is configured by the PMA’s, SINGLE ENDED 131

Figure 3.104 – WEST / EAST Ring 132

Figure 3.105 – Swapping both tributaries - Worker on the east line 133 Figure 3.106 – Swapping both tributaries - Worker on the west line again 134

Figure 3.107 – “Force Switch To Protection” option 134

Figure 3.108 – “Force Switch To Worker” option 134

Figure 3.109 – Collapse of the bandwidth when using the west line forcing to switch on it 135 Figure 3.110 – Lost packet count when forcing the transmission to the failed line 135 Figure 3.111 – Interesting logical topologies with 2 PMA’s and 2 frequencies 136 Figure 3.112 – Latencies obtained with the complete length of the ring 137 Figure 3.113 – Latencies for the ring starting at the A1 West TX and getting

back at the A3 East TX 138

Figure 3.114 – Latencies for the 2 tributaries running on the 2 complementary paths 139 Figure 3.115 – Resume of the possible paths’ packet transfer delays 140 Figure 3.116 – Resume of the power values obtained in the transponders’ Analogue

Monitoring 141

Figure 3.117 – Resume of the power values obtained in the TX/RX’s Analogue Monitoring 142 Figure 3.118 – Add Channel Failure alarms, due to the A1 west transmitter (A1 PMA) 143 Figure 3.119 – Alarms on the A1 PMA after solving the Add Channel Failure error 144

(11)

208 Figure 3.120 – Alarms on the A3 PMA after solving the Add Channel Failure error 144 Figure 3.121 – Configuration of the PMA32’s with no alarm on the OTM’s 145

Chapter 4

Figure 4.1 – Ring involving 3 PMA’s with Worker at the West TX for every single PMA 146 Figure 4.2 – Ring involving 3 PMA’s with Worker at the East TX for every single PMA 147 Figure 4.3 – Ideal situation: the 3 available frequencies on the west line at each PMA 148

Figure 4.4 – Core configuration @ A1 PMA 149

Figure 4.5 – Sub-rack configuration @ A1 PMA 150

Figure 4.6 – Sub-rack cabling @ A1 PMA 151

Figure 4.7 – Cross-connections window @ A1 PMA 151

Figure 4.8 – Signal Quality Monitor – available @ A1 PMA 152 Figure 4.9 – Remote mode, Sub-rack configuration @ A3 PMA 152 Figure 4.10 – Remote mode, Cross-connections window @ A3 PMA 153 Figure 4.11 – Remote mode, Sub-rack configuration @ A2 PMA 153 Figure 4.12 – Remote mode, Cross-connections window @ A2 PMA 154

Figure 4.13 – A1 real time alarms 155

Figure 4.16 – The desired configuration, with all the frequencies on the external path 156 Figure 4.17 – The configuration as it can be configured by the PMA’s 156 Figure 4.18 – Medium path delay for both Gigabit Ethernet traffics 157 Figure 4.19 – Comparison delays obtained in the 2 PMA’s configuration 157 Figure 4.20 – Medium path delay for both Gigabit traffics using the opposite direction 158 Figure 4.21 – Configuration with the 192.8 trib. being treated by 2 PMA’s only 158 Figure 4.22 – Shortest path for the 192.8, medium path for the 193.1 159 Figure 4.23 – Comparison delays obtained for the 2PMAs configuration’s shortest path 159

(12)

209 Figure 4.24 – Shortest path for both the 192.8 and the 193.1 tributaries 160 Figure 4.25 – Configuration to test the longest path delay, with single-ended 192.8 160 Figure 4.26 – Longest path for the 193.1; single ended & medium delay for the 192.8 161 Figure 4.27 – Configuration to test the longest path delay, with dual-ended 192.8 161 Figure 4.28 – Longest path for the 193.1; dual ended & shortest delay for the 192.8 162

Figure 4.29 – Final resume of the obtained path delays 162

Figure 4.30 – Add-drop operation requiring our 2 available frequencies 163 Figure 4.31 – Configuration of the different ISO levels of our infrastructure 165 Figure 4.32 – Double File Transfer on opposite directions

with Point-to-Point Link configuration 166 Figure 4.33 – Double File Transfer on opposite directions with Ring configuration 167 Figure 4.34 – Multiplexed signal created with two traffic flows on the same direction 168 Figure 4.35 - The picture shows a Centralized TDS Architecture example 170 Figure 4.36 – The picture shows a Fully Distributes TDS Architecture example 171

Figure 4.37 – Centralized TDS experimental TESTBED 172

Figure 4.38 – Fully Distributed TDS experimental TESTBED 173

Figure 4.39 – Discovered topology 174

Chapter 5

Figure 5.1 – Different types of MHL3000 enclosures 179

Figure 5.2 – Possible topology including different MARCONI-ERICSSON OMS families 183

Chapter 6

Figure 6.1 – The Italian backbone network by Wind-Infostrada 185 Figure 6.2 – Integration of networks by a superbackbone network 186 Figure 6.3 – Mesh (left) and ring (right) topologies in the Italian backbone solutions 186

Figure 6.4 – The Albacom backbone network 187

Figure 6.5 – The 2 layers of Telecom Italia’s latest strategies 188

(13)

210 Figure 6.6 – The evolution from the present situation to the future one 189

Figure 6.7 – The PHOENIX backbone network 190

Figure 6.8 – An ODXC and the different client layers 191

Figure 6.9 – DWDM OADM’s by Alcatel & Marconi-Ericsson 191 Figure 6.10 – The management chain in the Phoenix architecture 192 Figure 6.11 – Activation of a new working path in Phoenix 192

Figure 6.12 – GigaPop logical structure 194

Figure 6.13 – Interoute i-21 by Interoute Telecommunications 196 Figure 6.14 – European-Asian FLAG network by FLAG Telecom 197