View Full Version : Problem connecting Cat5e to Switch

05-31-2006, 11:53 AM
I have a 40m run of Cat5e cable that is connected at one end to a Linksys ADSL router that provides DHCP and DNS services.

When I plug the cable directly into the back of my PC it works perfectly.

However, if I plug it into a 10/100 Linksys Switch I am unable to obtain a DHCP address and even if I setup a static address I cannot ping the router.

Please can anyone provide a suggestion as it has driven me mad for about 6 hours today!!


05-31-2006, 09:27 PM
"I have a 40m run of Cat5e cable that is connected at one end to a Linksys ADSL router"
Are you using crossover or patch cable for this ?

"However, if I plug it into a 10/100 Linksys Switch"
I may be wrong, shouldnt crossover cable be used for that.

05-31-2006, 09:37 PM
From what I have read it should had required a crossover cable (or an uplink port) for the cable that connects two switches.

Let me explain a little more fully - the 40m cable comprised a 30m length plus a 10m length. Both cables are straight - no crossover. At the remote end the Cat5 is connected to the linksys ADSL router in all cases.

(1) Connect a switch to the 30m cable and the 10m cable to the switch. A PC locally connected to the switch or connected to the end of the 10m cable can get a DHCP address.

(2) Connect the 30m and 10m cables in one run. A PC connected to the end of the 40m run can get a DHCP address. If I attach a switch to the end of the 40m run and a PC to the switch it cannot get a DHCP address.

06-02-2006, 07:19 AM
The two devices, forget the pc for a second, must be connected one to the other via an uplink port.

For example a run a 15 node network. Each run has 5 pc's that connect to a switch via the regular ports. The three switches connect to the router. They use the uplink port.

You need to go DSL Modem------>switch (via uplink)-------->PC via regular port.

06-02-2006, 07:24 AM
The only flaw with this argument is that th switch we used can auto-detect and correct for cross-overs (Auto MDI-X).

Also when I connected the switch to the end of the 30m Cable then connected the wireless access point (incl 4 port switch) to the switch and connected my laptop to the wireless access point, it worked i.e. I took the 10m extension cable out of the network.

This suggests to me that there is something wrong with the 10m cable BUT what?

06-02-2006, 07:46 AM
Your descriptions of what you are connecting and what results yoiu are getting are not clear.

Please use diagrams.

If you think the cable is bad try a known working cable.....

06-02-2006, 07:03 PM
Crossover cables are for like devices. Switch and router connection won't need a crossover. You need to see if the link lights comes on to see if the cable doesn't work or not. If it needs a crossover it will not get link.

Plug a pc into the switch and another pc into the switch. Can you ping each other? It could be that the cables being used are pinned differenty. Look at the cable ends, check that the colors are the same at both ends for each cable i.e. cable from pd to switch and cable from router to switch. Make sure all cables are the same pin out.