The idea of a Light tree represented as a wavelength-routed optical network, which engages wavelength -department multiplexing known as WDM.
Relying on the underlying physical topology networks can be categorized into three generations:
a).First generation: these systems do now not rent fibre optic era; instead they appoint copper-based entirely or microwave era. E.g. Ethernet.
b).2nd generation: these networks use optical fibres for statistics transmission, but switching could be carried out within the electronic domain. E.g. FDDI.
c).3rd generation: in these networks, each facts transmission and switching is performed within the optical area. E.g. WDM.
WDM wide area networks appoint tunable lasers and filters at getting right of entry to nodes and optical/digital switches at routing nodes. Gain entry to a node might also transmit signals on distinguishing wavelengths, which are coupled into the fibre the usage of wavelength multiplexers. A visible sign passing through an optical wavelength-routing switch (WRS) can be routed from an output fibre without present process optoelectronic conversion.
A light path is an all-optical channel, which can be used to carry circuit switched traffic, and it could span more than one fibre links. Assigning a selected wavelength to it sets these up. In the absence of wavelength converters, a light path might occupy the same wavelength continuity constraint.
A light route can create logical (or digital) neighbours out of nodes that can be geographically far apart from every different. A light direction contains no longer only the direct visitors between the nodes it interconnects but additionally the visitors from nodes upstream of the source to nodes upstream of the vacation spot. A prime goal of light direction communique is to reduce the range of hops a packet has to traverse.
Under light route communication, the community employs an equal variety of transmitters and receivers because each mild course operates on a factor-to-factor foundation. But, this method isn’t always capable of ultimately apply all the wavelengths on all the fibre links within the network. Additionally, it isn’t capable of conclusively make the most all the switching functionality of every WRS.
A light tree is a point to factor-multipoint all optical channel, which might also span multiple fibre links. Hence, a Light tree allows unmarried-hop communication between a source node and a hard and fast of vacation spot nodes. For that reason, a mild tree primarily based digital topology can extensively reduce the hop distance, thereby increasing the community throughout.
Requirements for Light Tree:
1. Multicast -successful wavelength routing switches (MWRS) at each node in the community.
2. more optical amplifiers inside the community.