I am having trouble connecting an "el cheapo" switch to a 2948G. I have set up a training room and needed a high density of PCs so I plugged a switch into a 2948G port. There is a button for up-link abd I get a link light and the 2948G indicates it is connected. I plug PCs into the "el cheapo" and can't get a dhcp address. They all have link lights and work when plugged directly to the 2948G. I have swapped the "el cheapo" with an old Cabletron and connections worked for a few days but now nothing. I had turned portfast off on the downlink port on the 2948G. Help.