Unfortunately I've never touched a Dell switch, so I really can't give you a specific step-by-step "how-to" on that.
If you have the ability to SSH/telnet into your switch, you should be able to check this from the switches command-line interface.
As an example, I can SSH into our HP ProCurve switch and issue a command like 'show interfaces brief'. This will give me an output that looks something like:
Code:
Status and Counters - Port Status
| Intrusion MDI Flow Bcast
Port Type | Alert Enabled Status Mode Mode Ctrl Limit
------- --------- + --------- ------- ------ ---------- ----- ----- ------
1 10/100TX | No Yes Up 100FDx MDIX off 0
2 10/100TX | No Yes Up 100FDx MDIX off 0
3 10/100TX | No Yes Up 100FDx MDIX off 0
4 10/100TX | No Yes Up 100FDx MDIX off 0
5 10/100TX | No Yes Up 100FDx MDIX off 0
6 10/100TX | No Yes Up 100FDx MDI off 0
7 10/100TX | No Yes Up 100FDx MDIX off 0
8 10/100TX | No Yes Down 100FDx MDIX off 0
9 10/100TX | No Yes Up 100FDx MDIX off 0
10 10/100TX | No Yes Up 100FDx MDI off 0
11 10/100TX | No Yes Up 100FDx MDIX off 0
12 10/100TX | No Yes Up 100FDx MDIX off 0
13 10/100TX | No Yes Up 100FDx MDIX off 0
14 10/100TX | No Yes Up 100FDx MDIX off 0
15 10/100TX | No Yes Up 100FDx MDIX off 0
In the
Mode column, you can see
100FDx is displayed. This tells me that the port is running 100Mbps and set for full-duplex.
You didn't mention what kind of endpoints you're using. As another example, on the Aastra 57i, you can check these settings from the phone's interface by pressing
Options -> 3.Phone Status -> 2.LAN port. This shows me the link state, speed, duplex, and whether the link was autonegotiated or statically set.
This is at least something to check and eliminate as a potential problem. My biggest problem with duplex mismatch has always been with 3Com. The switch port typically auto-negotiates a half-duplex connection while the device believes it to be full-duplex. You'll have all kinds of wonderful errors on the port - something else your switch should show you.
What is the model number for your Dell switch? If I can find a manual, I might be able to guide you further.