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A Method to Determine the Optical Number of Wavelengths in an APSON

IP.com Disclosure Number: IPCOM000126689D
Original Publication Date: 2005-Aug-25
Included in the Prior Art Database: 2005-Aug-25
Document File: 4 page(s) / 264K

Publishing Venue

Siemens

Related People

Juergen Carstens: CONTACT

Abstract

The bandwidth cost in optical networks has been reduced in the last years due to some technological breakthroughs. Moreover, reducing the number of optical fibers in the network lowers other equipment cost indirectly, considering as example the optical switch. Reducing the number of optical fibers means reducing the number of input and output ports in the switch, which inevitably reduces its complexity and cost. One of the advantages of APSON (Adaptive Part Switched Optical Networks) is their ability to reduce the number of wavelengths needed in a network in order to transfer a certain volume of traffic in comparison to other approaches such as OBS (Optical Burst Switching) or especially ASON (Automatic Switched Optical Networks). Therefore, it is important to determine the factors that have an influence on the reduction of the number of required wavelengths in APSON, as well as to quantify this reduction. Until now there is no solution for this problem. In the following an analytical model is presented, which is able to identify the mechanisms through which APSON is capable of reducing the number of needed wavelengths. In addition the model presents an exact quantification of APSON’s potential in the reduction of the number of wavelengths. Moreover, a novel method based on this analytical model is presented. According to this method, considering a given network and a certain traffic volume, the optimal number of wavelengths required by APSON is obtained. In most instances this number will be below the number of wavelengths required by ASON in the same conditions.

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A Method to Determine the Optical Number of Wavelengths in an APSON

Idea: Dr. Miguel de Vega Rodrigo, DE-Munich

The bandwidth cost in optical networks has been reduced in the last years due to some technological breakthroughs. Moreover, reducing the number of optical fibers in the network lowers other equipment cost indirectly, considering as example the optical switch. Reducing the number of optical fibers means reducing the number of input and output ports in the switch, which inevitably reduces its complexity and cost. One of the advantages of APSON (Adaptive Part Switched Optical Networks) is their ability to reduce the number of wavelengths needed in a network in order to transfer a certain volume of traffic in comparison to other approaches such as OBS (Optical Burst Switching) or especially ASON (Automatic Switched Optical Networks). Therefore, it is important to determine the factors that have an influence on the reduction of the number of required wavelengths in APSON, as well as to quantify this reduction. Until now there is no solution for this problem.

In the following an analytical model is presented, which is able to identify the mechanisms through which APSON is capable of reducing the number of needed wavelengths. In addition the model presents an exact quantification of APSON's potential in the reduction of the number of wavelengths. Moreover, a novel method based on this analytical model is presented. According to this method, considering a given network and a certain traffic volume, the optimal number of wavelengths required by APSON is obtained. In most instances this number will be below the number of wavelengths required by ASON in the same conditions.

The Effective Wavelength Capacity:

Figure 1 shows the analytical model of a 2WR-OBS (Wavelength Routed-OBS) network, which is used. A total number of NS sources send information through a common link (optical fiber) which capacity C is equal to Nλ wavelengths * Cλ capacity of each wavelength (C = Nλ*Cλ). The average IP packet arrival rate of each source is represented by λIPi , and the average IP packet size by µ. Each burst from each one of the NS sources is carried out by one of the Nλ available wavelengths. The mapping between wavelengths and bursts is done according to a wavelength assignment or wavelength scheduling algorithm, which selects the wavelength on which a burst will be sent according to some performance criteria. It is assumed that the load of the NS traffic sources is equally distributed among the Nλ wavelengths of capacity Cλ. In the following a single wavelength (and its capacity Cλ) of the optical fiber and its capacity C is analyzed.

A limiting factor of the performance in APSON is the path setup time (tsetup). Every time a new burst is sent, a path setup time is elapsed. During this time no information can be sent and the higher the frequency with which bursts are sent, the more bandwidth will be reduced due to more frequent pat...