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Hub as Repeater

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by r. a. caluste 3 views

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I have layed down an underground cable inside an unused conduit from our main building to our warehouse. The warehouse is more than 100 meters. In between the warehouse is a weatherproof box where I plan to put a hub to act as a repeater to resolve the 100 meter limitation of the cat5 cable. Will this work with an ordinary hub (uplinked) ? Any suggestions?

Thanks.

13 replies

by road-dog

It should work, Is there 115AC in the box? If not, you've got problems. Pay attention to the 3-4-5 rule...

by bohicam1

As long as the hub is an "active hub"....meaning it is plugged in, you will have no problems. Make sure you always have access to this box as your hub may need resetting once in a while.
Good luck!

Mike

by r. a. caluste

Yes, we have prepared for that already (putting an AVR into the box) even before designing the weatherproof box. I am more concerned about the repeater hop counts. Thanks for answering anyway.

by don

An ordinary hub will not act as a repeater. A repeater or a switch will. You realize the repeater needs to be within the 100 meter limitation, meaning somewhere in the middle of the conduit.

by nettek

I don't like to step on answers, but answers 1 and 2 are correct, and answer 3 is incorrect. A hub, by definition, indeed acts as a repeater.

The 5-4-3 rule means than you can have 5 network segments, 4 four repeaters (hubs), but only 3 segments can have computers connected to them. So if you plan on setting up your network as follows:
Hub (main building)<-> Hub (in box, no users)<-> Hub (warehouse), you should have no problems.

by r. a. caluste

Thank you for your suggestions. i have been reading articles regarding repeater hop counts. According to the articles, the 5-4-3 repeater hop count rule applies to 10 Mbps ethernet network. However, on a 100BaseT Fast ethernet network, there is a maximum of 205m network diameter or at least two class II hubs (two repeater hops). Also, this rule can be extended by using a switch since it effectively separate the network into individual segments with their own collision domains.

I would like to hear comments about the above topic from experts. I am upping the points for continuing discussion.

Also, to provide further input, network layout is below: (100BaseT, Fast Ethernet)

[Main Bldg, Second Floor] Switch (Cisco Catalyst) -> [MB, Ground Floor] 3com (Officeconnect, Class II hub) -> [Box] Planning to use Dlink Switch -> [Warehouse] Planning to use 3com Officeconnect

Should I replace the Hub (repeater) located at the Main bldg, ground floor from 3com officeconnect to a switch?If so the layout will be as follows:

switch -> switch -> switch -> class II hub or will the switch -> class II hub -> switch -> class II hub work?

Thanks.

by jose mir

switch -> class II hub -> switch -> class II hub will work fine.
As you state, switches modify the 5-4-3 rule. Switches are, by construction, multiport bridges.
There are other solution to your problem. You can use a fiber patch cord and two coperto fiber transducers. you can find some info at blackbox.com

Regards,

Jose P Mir
jpm@jpmir.net

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