PowerConnect 3348 - Computers cannot see the network when first bootup

Question

I have just deployed 3 PowerConnect 3348 switches on my network and having connection problem from many computers.  First some background on the switches.  Running on the latest firmware 1.1.0.42.  After receiving the the switches, I follow the 'Getting Started Guide' and created 1 VLAN and assigned IP addresses.  No other configuration.  I then installed the switches onto my network, replacing my 3Com hubs. Here's my problem.  About 20 computers are having connection problem when plug into the switches.   When the machines first bootup or restarted, and I try to login to my domain, I keep getting an error 'The system cannot log you on now because the domain is not available', as if the machine is not connected to the network at all.  All these machines are new Dell Dimension 4600 with integrated Intel Pro/100 VE NIC (with latest BIOS).  When I re-connect these machines back to my old 3Com hubs, everything works fine again.  I have been playing with this problem for a few days already and found a couple of workarounds.  The machines cannot see the network when it is first bootup or restarted.  However, if I just logon locally and then log off (not restarting), then log back on to my domain, everything works fine again.  It looks like the machines are having some kind of hand shaking issues with the switches.  By first going into Windows environment the then log off, it get resolved.  Another workaround I have discovered is that if I manually set the Link Speed and Duplex on the machines to 100 Mbps and full duplex, while leaving the port speed on the switches as 'auto-negotiate', everything works fine again. What am I doing wrong here?  Is there some other configurations I need to set?  Please help.   Thanks.

GregG1 · Answer

The problem you are having is most likely related to Spanning Tree. The clients are booting faster than the time it takes for Spanning Tree to allow traffic to forward on the port.

You can disable Spanning Tree on the problematic ports using the "spanning-tree portfast" command from interface configuration mode.

GregG1 · Answer

This is neither a problem nor a bug with the PowerConnect switches. Spanning Tree (IEEE 802.1D) is an industry standard protocol that was created to prevent bridging loops from causing broadcast storms that will crash an entire network. Spanning Tree is enabled by default on all PowerConnect managed switches as well as many other vendors of networking products.

Spanning Tree can be disabled globally or on a port-by-port basis. It is recommended to leave Spanning Tree enabled on uplinks to other network devices and disable it on client ports. With Spanning Tree enabled on the uplinks, if someone were to accidentally create a loop in the network, the protocol will block the redundant connection to prevent a broadcast storm.

yitl · Answer

Hi Greg,

Thanks for replying. If I am reading you correctly, do you mean that there is a problem in Dell's PowerConnect switch in which it can't keep up with the Dell machines? I find it hard to believe!! If Dell can't get their own products to work together, who will?? FYI, I have been a long-time Dell customer by puchasing my workstations and servers exclusively from Dell. What you have just told me really came as a surprise.

Since Dell has realized this issue already, what is being done to fix this problem?

What you have suggested is just another workaround. If I paid a sports car with turbo engine, I sure hate to have to disable the turbo engine feature in order to get my car started.

Thanks.

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