avq@goya.dit.upm.es (Alfredo Villalobos) (08/30/90)
Unshielded Twisted Pair Implementions of Ethernet at 10 MBits/Second. 4 Concentrator (Hub) limitation We would like any information on the reasons why there is a limit of 4 hubs or concentrators between any two devices on some UTP implementations of ethernet and not on others. Specifically, Hewlett Packard in their StarLAN network specify a maximum of four hubs between the most remote network devices and Synoptics specify a maximum of four retimings, which in the case of their newer products also means a limit of four concentrators. However AT&T, in their version of StarLAN, permit many more hubs to be placed between any two network devices. While they do not specify an exact number for every case the maximum would appear to be about seven. We had assumed that this limit was because of delays in reporting collisions, especially with small packets, however the absence of such a tight limitation in the AT&T version would seem to contradict this. We would particularly like to know how the proposed 10BaseT standard affects this. Any information will be gratefully received, Regards,