🚀 go-pugleaf

On Sat, 10 Apr 1999, Michael Salem <4ms2u$ms@michaels.demon.co.uk>
wrote:
>> > Does anyone know what the limit is for max length of CAT 5 cable between
>> > a workstation and a hub. I have to extend our network over a distance of
>> > about 600 metres too multiple workstations. I am presuming that this
>> > would need some form of booster. Also I believe that there is limit to
>> > the number of hubs that can be joined on an ethernet network and that
>> > this is fairly low, something like 5  24 port hubs, is this correct or
>> > am I talking rubbish.
>> 
>> Each utp cable max is 100 metre. I believe you can cascade 4 hubs
>> together so the path between any 2 workstations cannot have more
>> than 4 hubs. If however you use hubs with bnc and use a thin
>> ethernet backbone, then you should be able to connect 30 hubs
>> together.
>
>Additional notes: the maximum length of a thin Ethernet segment is 
>185m; thick Ethernet will go to 500m. Fibre will handle 1km 
>inter-repeater length. With some small print (distances are shorter 
>if the maximum permissible number of repeater sets is used).
>
>I don't see that you can connect 30 hubs: wouldn't they fall foul of 
>the IEEE standard:
>   
>   The transmission path permitted between any two DTEs may consist
>   of up to five segments, four repeater sets (including optional
>   AUIs), two MAUs, and two AUIs. 
>
>Best wishes,

30 hubs may coexist on a 10Base-2 or 10Base-5 (Thin or thick) ethernet
segment, as there is a maximum of two repeaters between any two DTE's.
Thus the backbone may consist of up to three segments separated by two
repeaters.

Anything in excess of this will require two or more seperate ethernets.
In other words use a repeater to separate nets. A repeater is a device
that has addressing tables which allow it to determine which port, if
any, to forward a packet on. Depending on the number of DTE's involved,
subnetting may be a possibility here. And of course, the coaxial
segments may be dispensed with altogether, if you fit UTP adapters to
the repeater's AUI port. Finally, not recommended, but a possiblity
dependent on the volume of traffic is the use of overlength drop leads.

Dont forget, that the 100M hub to DTE limit should take account of patch
leads and drop leads, so if you using 2.5M on each, the maximum allowed
on your cabling system (socket to socket) is 95M. However, some sites do
choose to push this overspec. The tradeoff is at the expense of
increased collision frequency, which again is a function of net traffic.
I'd advise adhering rigidly to the limits if you anticipate ever running
the network at speeds > 10MHz.

Finally, fibre will handle considerably more than 1km inter-repeater
distance if you specify monomode fibre. Sorry, but I don't have precise
figures to hand.

-- 
Barry Smith
Email: sax (at) wychcraft.demon.co.uk <--  I don't want ANY spam!