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Functions

Industrial Ethernet OSM/ESM

C79000-Z8976-C068-10

Functions

This chapter discusses the general functions of the OSM/ESM, in particular the

properties of the switching technology.

Increased Network Performance

By filtering the data traffic based on the Ethernet (MAC) address of the DTEs,

local data traffic remains local, only data intended for nodes in another network

segment are passed on by the OSM or ESM. This reduces the data traffic in the

network segments and lowers the network load in the network segments.

Simple Network Configuration and Network Expansion

OSMs and ESMs store the data received at the ports and the direct it to the

destination address. The restriction of the network span resulting from collision

detection (CSMA/CD) ends at the OSM/ESM port. With multimode graded-index

fibers, a total network span of up to 150 km and more can be achieved without

problems. With the OSM ITP62-LD, the monomode fibers allow a network span of

up to 1300 km.

Limitation of Errors to the Network Segment Affected

OSMs and ESMs only pass on valid data. Invalid packets are discarded so that

bad packets within a network segment have no effect on any other segment

attached to the OSM/ESM.

Learning Addresses

By evaluating the source addresses in the data packets, OSMs/ESMs

automatically learn the addresses of the DTEs attached via a particular port. If an

OSM/ESM receives a data packet, it directs this packet only to the port via which

the appropriate DTE can be obtained.

An OSM/ESM can learn up to 7000 addresses.

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Siemens ESM Manuel d'utilisateur Page 29