Ahmed Musa, John Medrano, Virgillio Gonzalez, Cecil Thomas

University of Texas at El Paso

Circuit Establishment in a Hybrid Optical-CDMA and WDM All-Optical Network Using the Flooding Mechanism

Mehdi ShadaramUniversity of Texas at San Antonio

* Introduction - A high demand on higher capacities ( Why all-optical network?)

- Approaches to make the transmission medium has a scalable bandwidth (BW) capacity

* Backbone network- Optical-Optical-Optical (OOO)- Optical-Electrical-Optical (OEO)

* Routing Benefits and Disadvantages

* Proposed routing algorithm

* Routing (Setup Optimal Lightpath) Steps

* Routing Implementation Using Flooding Mechanism

* Example

* Conclusions

Outline

Introduction

• A high demand on higher capacities because ofMultimedia services.Video conferencesInternet.Environmental remote sensing.Medical imaging

• Approaches to make the transmission medium has a scalable bandwidth (BW) capacity

Install more fiber (costly) Exploit the BW of existing fiber using higher data rates and

multiplexing techniques such as Wavelength Division Multiplexing (WDM).

- Coarse WDM (# of Lambdas λ’s < 10)

- Dense WDM (# of λ’s > 10)

Time Division Multiplexing (TDM). Code Division Multiplexing (CDM).

Backbone networkOptical – Electrical – Optical (OEO)

Optical – Optical – Optical (OOO or Photonic NW)

Photonic networks

Advantages– Solve the electronic equipment bottleneck

– Exploit the existing network

Disadvantages - Photonic NW is a complex system ( a large number of

different functions must cooperate for a network such as

– transmission

– Routing and Switching

– Control and management

– etc.

Routing Benefits Support services such as connection on demand Enriches the service level agreement (SLA) by supporting (Protection and

Restoration). Improves bandwidth (BW) efficiency and source utilization of the network.

Intractable problem (NP-Complete). Therefore, assumptions and heuristics are used to reduce the process complexity.

Routing disadvantages

Upgrading the Network by : Increase bit rate from 2.5 up to 160 Gb/s #of wavelength up to 256 Narrowing the channel spacing Is significantly affected by Routing Algorithm due to Physical impairments

Table 2: Optical Linear and Non-linear Impairments

Class Impairment Constraint

Linear

Attenuation (Loss)Optical amplification implying OSNR degradation

Chromatic dispersion (GVD)Compensation fiber or limit on the total length of fiber links

Polarization-mode dispersion (PMD)

Total length of fiber links

Non-linear

Self-phase modulation (SPM) NLP constraint

Cross-phase modulation (XPM) NLP constraint

Four – Wave Mixing (FWM) Negligible (per system design)

Simulation Roman scattering (SRS)

Modification of signal power (and thus NLP)

Stimulated brillouin scattering (SBS)

Negligible

NoiseAmplifier spontaneous emission (ASE)

OSNR degradation (resulting in constraint on the number of fiber spans)

N e twor k - Laye r M odu le

C all R eq u es t

L o o k f o r a na va i l a b l e l i g h t p a t h( L P ) u s i n g a R W A

B lo ck ca ll

n o L Pa v a ila ble

A dm it c al l

W a v e le n g th a n dC o de A s s ig n m e n t

C a lcu la te L P s M etrics

C a n dida te L PPh y s ica l - L a y e r M o du le

C h oo se th e b est P a th" M in . C ost P a th "

S witch M e tricsF ibe r M e trics

A p p ly V etirb iA lgo rith m on

th e clo sed L o op

C h oo se th e low estm etric P a th

C a lcu la te lig h tpa th (L P) M e trics

Routing algorithm flow diagram

Proposed routing algorithm

– Used Optical CDM and WDM to label the optical signal

– Takes into account the physical impairments existing in NW

– Set up the lightpath based on calculating the cost of all possible paths from ingress to egress node.

Routing (Setup Optimal Lightpath) Steps– First Step :- Calculate the fiber metrics.

– Second Step :- Calculate switch metrics.

– Third Step :- Apply Viterbi algorithm on each close loop from the source to destination to select the minimum metric.

Fiber metrics

65,535x N

)PMDLL

GVDLL

atten.LL(

ji,M

Where N is the normalization factor

I/P Metric O/P Metric

Link merits (L) :-Attenuation Dispersion D

Where Δ M 'M ijij , and is a function of Attenuation and Dispersion

D

Δ M (i) M(o)

klk2k1

2 l2 22 1

1 l1 211

mmm

m.......mm

m.......mm

1 2 lC1C2

Ck

klk2k1

2 l2 22 1

1 l1 2

m 'm 'm '

m '.......m 'm '

m '.......m '

1 2 lC1C2

Ck

11m '

Wavelengths are selected based on ITU-T G.692 WDM grid

10 192.00 1561.42  

11 192.10 1560.61 Long band

12 192.20 1559.79 Long band

13 192.30 1558.98 Long band

14 192.40 1558.17 Long band

15 192.50 1557.36 Long band

16 192.60 1556.55 Long band

17 192.70 1555.75 Long band

18 192.80 1554.94 Long band

19 192.90 1554.13 Long band

20 193.00 1553.33 Long band

21 193.10 1552.52 Reference frequency

22 193.20 1551.72 Long band

23 193.30 1550.92 Long band

24 193.40 1550.12 Long band

25 193.50 1549.32 Long band

26 193.60 1548.51 Long band

Routing Implementation Using Flooding Mechanism(1) The forward signaling procedure

(2) The backward signaling procedure.

(3) The clearance procedure

D e st . S r c .H o p

C o u n tH e lloT im e r

In p u tP o r t

O u tp u tP o r t

In p u tP o r t

O u tp u tP o r t

M 11

M 1 2

M 1 3

M n m

...

M ( ')1 1

M ( ')n m

...

M ( ')1 2

M ( ')1 3

~ ~M (k )

1 1

M (k )n m

...

M (k )1 2

M (k )1 3

In p u tP o r t

O u tp u tP o r t

~ ~S wit ch 1 S wit ch 2 S wit ch k

C) Input

D estin a ta io na d d ress

S o u rcea d d ress

N etw o rkD im en sio n

( C

) Input

( C

) Input

D e st . S r c .H o p

C o u n tT im e r

In p u tP o r t

O u tp u tP o r tM 11

M 1 2

M 1 3

M n m

...

S wit ch 1

D estin a ta io na d d ress

S o u rcea d d ress

N etw o rkD im en sio n

(n u m b er o f n o d e )

( C

) Inp

ut

2 x 2 x 2 x 2

2

3

S wit ch # X

1

S wit ch Y

λ1C1 λ1C2 λ2C1 λ2C2

D A 310ps 31

1111

4

λ1C2

76

53 IP1

λ1C1

λ2C1 λ2C2

C1 C2 C1 C2 λ1 4 5 λ1 7 6 λ2 5 7 λ2 9 7

C1 C2 C1 C2 λ1 8 10 λ1 11 9 λ2 7 8 λ2 9 8

C1 C2

λ1 4 5 λ2 5 7

M in( )

C1 C2 C1 C2 λ1 4 5 λ1 7 6 λ2 5 7 λ2 9 7

C1 C2 C1 C2 λ1 8 10 λ1 11 9 λ2 7 8 λ2 9 8

C1 C2

λ1 4 5 λ2 5 7

M in( )

C1 C2 C1 C2 λ1 4 5 λ1 7 6 λ2 5 7 λ2 9 7

C1 C2 C1 C2 λ1 8 10 λ1 11 9 λ2 7 8 λ2 9 8

C1 C2

λ1 4 5 λ2 5 7

M in( )

S witch Y

λ 1 C 1

λ 1 C 2

λ 2 C 1

λ 2 C 2

D A 2x xx 31

1111

λ 1 C 1

λ 1 C 1

λ 1 C 1

λ 1 C 1

4557

S witch X

1 3

S witch Y

λ 1 C 1

λ 1 C 2

λ 2 C 1

λ 2 C 2

D A 2x xx 31

1111

λ 1 C 1

λ 1 C 1

λ 1 C 1

λ 1 C 1

4557

S witch X

1 4

S witch Y

λ 1 C 1λ 1 C 2

λ 2 C 1

λ 2 C 2

D A 2x xx 31

1111

λ 1 C 1

λ 1 C 1

λ 1 C 1

λ 1 C 1

4557

S witch X

1 2

Calculate Switch Metrics

C1 C2

λ1 1.0 1.0 λ 2 1.0 1.0

C1 C2

λ1 1.0 1.0 λ 2 1.0 1.0

Switch C

2x2x2

2

13

4

C1 C2

λ1 ? 1.0 λ 2 1.0 1.0 C

C1 C2

λ1 1.0 1.0 λ2 1.0 1.0

L 1

C1 C2

λ1 ? 1.0 λ 2 1.0 1.0

C1 C2

λ1 ? 1.0 λ 2 1.0 1.0

L 2

C1 C2

λ1 ? 1.0 λ 2 1.0 1.0

C1 C2

λ1 ? 1.0 λ 2 1.0 1.0

C1 C2

λ1 1.0 1.0 λ 2 1.0 1.0 A

C1 C2

λ1 ? 1.0 λ 2 1.0 1.0

L3

C1 C2

λ1 1.0 1.0 λ 2 1.0 1.0

Switch B

Switch A

2x2x22

1 3

4 2x2x22

13

4

B C1 C2

λ1 1.0 1.0 λ 2 1.0 1.0

N e tw o r k M a n a g e r( S i g n a l Tr a n s fe r P o i n t )

S ig n al in g L in k

Fibe r L in k

Data start brusted through using the selected path (A B C)

S wit ch in g Po in t(S ig n a l Tra n s fe r Po in t )

s w itc h A

s w itc h B

1

2

3

4

1

2 3

4

1

2

3

4

1

2 3

4

s w itc h C

s w itc h D

n o de A

n o de D

Ex te rn a l n o de

ph o to n ic s wit ch

S ig n a lin g L in k

Fibe r L in k

B is e ct io n a l B a n dwidth

B is e ct io n a l B a n dwidth

Network Model and Bisectional Bandwidth

Network Characteristics and Switch Metrics

Switch Metrics Matrix for 2 wavelengths x 2 codes

Fiber Lengths : distance (Switch A, Switch B) = 30 km distance (Switch A, Switch C) = 20 km distance (Switch B, Switch C) = 25 km distance (Switch B, Switch D) = 15 km distance (Switch C, Switch D) = 20 km

λ1C1 λ1C2 λ2C1 λ2C2

1224

2142

2412

4221λ1C1

λ1C2

λ2C1

λ2C2

λ1 λ2

0%

10%

20%

30%

40%

50%

60%

0 5 10 15 20Traffic Load (Erlangs)

Blo

ckin

g P

roba

bilit

y

Blocking due to entry port

Blocking due to NW resources

Blocking probability of NW (2 wavelengths and 2 codes) at different traffic load

Blocking probability due to NW resources (2 wavelengths and 2 codes) at different traffic load

Blocking Probability due to NW Resources

0.00%

1.00%

2.00%

3.00%

4.00%

5.00%

6.00%

0 2 4 6 8 10 12 14 16

Traffic Load (Erlang)

Blo

ckin

g Pr

obab

ility

(%)

Impaired NW

Ideal NW

Ideal Switch/Impaired Fiber

Ideal Fiber/Impaired Switch

Conclusions

This algorithm help improving the NW Performance.

Flooding mechanism is used to set up the path (used in the control plane of the network independent of the information path.

Flooding mechanism is emulated in in the network manager.