[lug] OT: Switch versus hub problem

[Andrew Diederich]

I'm trying to figure out why a switch and a hub are acting differently
on my network for DHCP.  I have a cable modem (Linksys WCG200,
firmware version 1.1.2.9.4-1104).  When I put a switch behind that,
then plug various PCs and laptops into the switch, only the first
device gets an IP address from the DHCP server on the cable modem.  I
swapped out the switch (a netgear ProSafe 16 port 10/100 FS116) with a
plain old hub, and now multiple devices can get IP addresses.

I had really assumed it was the cable modem with the issue, rather
than the switch, figuring the modem got confused seeing multiple MAC
addresses on one port.  Since swapping out the switch for the hub made
the problem go away, it looks like that's not the case.

Can anyone think why it'd work this way?  I had thought that the
switch would broadcast / pass through the DHCP requests to all devices
plugged into it.

Originally I didn't have a hub or switch at all, but the DHCP requests
got lost along the way entirely.  The network looked like modem > wall
cable > patch cable > laptop.  Plugging directly into the modem
worked, but I only like working in the basement so much.

Thanks for the help.

-- 
Andrew Diederich