HUB&switch

[David Rohleder]

dan at obluda.cz (Dan Lukes) writes:

> >
> >
> >Full duplex muze byt tazen v podstate na libovolnou vzdalenost (je
> >omezena pouze vlastnostmi prenosoveho media - 10 km dlouhy TP by asi
> >nefungoval :-)
> >
>     No, jenze vlastnost media obvykle delku kabelu zkracuje podstatne
> vyrazneji nez omezeni protokolu - zatimco zpozdeni limituje 10BaseT na
> cca 2,5km a 100BaseT na cca 250m, vlastnosti media limitovaly delku
> kabelu na 175m u 10Base2 (300m u extended verzi), 500m u 10Base5 a 100m
> u 10BaseT a 100baseT. Lepe to dopada jen v pripade optiky, kde skutecne
> obcas narazi delka kabelu drive na omezeni protokolu nez na omezeni media.
>
>     Takze, abych se vratil k prispevku na ktery reaguji - full-duplex
> muze byt skutecne tazen na libovolnou vzdalenost, ale zarucenou
> funkcnost ma na stejnych 100m jako half-duplex ...

To nechapu. Ale tady je citace:

Since full duplex operation does not use CSMA/CD, this distance
restriction no longer applies. Regardless of the data rate of the LAN,
the length of a full duplex Ethernet link is limited only by the
physical transmission characteristic of the medium. While twisted pair
links may be used at distances on the order of 100 m, optical fiber may
be used at distances up to 2 to 3 km (multimode fiber) and 20 to 50 km
or more (single mode fiber). With appropriate line drivers and signal
regeneration, there is no reason why a full duplex Ethernet link
cannot be extended across national and international distances using
satellite, private fiber, or other technologies. The distance
restrictions of CSMA/CD no longer apply.


Rich Seifert: The Switch Book

Autor je predsedou a editorem nekterych standardu IEEE 802.X


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David Rohleder						davro at ics.muni.cz
Institute of Computer Science, Masaryk University
Brno, Czech Republic
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