connect switch to hub?

ody1 · 04-12-2004, 08:07 AM

Hello everyone!

I'd really appreciate your info on how to set up a lan, using both switch and hub. I have a 3com switch and a 3com hub. Both have a button for uplink or normal mode. The question is: What's the proper way to achieve connection? What kind of cable do I use (straight or crossover)? And what should be the button state? I've tried several combinations. I noticed that even when all lights are on (of hub,switch), I still can't ping the pc's that belong to the switch network, from a pc that belongs to the hub network (and reverse). The ip's are all set properly. When I left out the hub and connected a pc directly to the switch , ping worked fine.
Thanks in advance..

muah · 04-12-2004, 08:23 AM

U should decide which of those devices will be "higher" in your imaginary network hierarchy, lets say it will be the switch. So u will connect your hub (using uplink port) to your switch (using normal port) via normal patch cable (not crossover) and it will work.

Other option is to connect them both using normal ports - then u would need a crossover cable.

david_ross · 04-12-2004, 08:25 AM

If you are using an uplink port then you only need a striaght through cable. One uplink to one ordinary port. This lets you use the other uplink port to link to a third hub/switch to create an even longer chain

Code:

               Switch
     ||  ||  ||  ||  ||  ||  ||  #
                                  \
                                   \
  # = Uplink Port                   \
 || = Normal Port                    \
  \ = Straight Cable                  ||  ||  ||  #
                                            Hub

edal · 04-12-2004, 08:42 AM

Hi there

For a small network you should be able to use either a hub or a switch. When you set a port to 'uplink' all it does is swap the transmit and receive pairs, this has the same effect as a crossover cable. This also gives you a great way of testing cables without a PC, connect a standard port and an uplink port together and both sets of port lights should come on.

As for the difference between switches and hubs the best explanation I have heard is as follows:

A hub works in a similar way to a taxi radio system. The base station issues instructions which all cars can hear but only the intended car responds to the message, all others ignore it. When the car replies to the message all other cars also hear but only the base station takes action. It is in other words a BROADCAST system.

A switch works in a similar way to the cellphone system. By examining the packets of the signal only the intended recipient gets to hear the message, others ignore it because the address/number is wrong. Switched networks are therefore more efficient.

Ed Almos
Budapest, Hungary