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HELP! Changed from Hubs to Switches

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by swetbak

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I'm pulling my first all nighter. Just taking on the simple job of changing from 10Mb Hubs to 10/100Mb Switches. Nothing has gone right. First, I have a 12 port fiber hub that connects to one of the new switches thru a fiber module. Well there was no "link" when connected to the new switch. Easy enough, I just reconnected the old hub that had the fiber originally into one of the switches. After resetting swithes and remote hubs, I was able to get those distant machines on the network. I'll work on the new fiber module later.
For some reason, I have a large # of machines(Win 95) that can't authenticate thru the server (Novel 3.12). These are connected directly to one of the switches. Funny thing is some machines on the same switchcan not even "ping" those machines, but others can. I've moved all the connections to different ports and different switches. Even moved the server to a different switch. I've rebooted all the machines.
I don't understand what could be going on. All I did was replace 4 hubs with 3 switches.
No problem with cabling or "link". We have a Unix box that ALL machines are able to access, even the ones that cann't authenticate.
Can anyone give some insight to this mystery?

7 replies

by vinnyd

To connect to the Unix machine are you using TCP/IP?

And to connec to the novell 3.12 server I would assume you are using IPX/SPX 802.2 frames.

If the novell 3.12 server was upgraded to 3.12 you may still be using 802.3 frames.

Try loading the TCP/IP protocol on the novell server and assign it an IP address in the proper range. Then see if you can ping the novell server.

Or you can load the 802.2 frame on the novell server if it is not loaded and then see if that works better for connectiing.

by don christner

Another problem is if you have your NICs and switches set to AUTO. Many problems with allowing them to select their own speed. You're better off to lock them into 10Mb or 100Mb.

Don

by shanghai sam

The switches set at auto and are not changeable. Most of the NIC cards are only 10Mb. All the 10/100 machines were working.
Thanks

by ebob

If your network was working with a hub, then putting a switch in should not mess things up too badly (as you suspected). A switch is really not much more than a smart hub, after all.

Here's how I have done this type of exercise and neatly avoidedthe all-nighter in the process. I believe the "trick" is to pilot one or 2 systems that are not ctitical to get up the learning curve.

Hang the switch in the rack and power it up. No VLANs, no tricky configuration: just power it up. Connect my hub to the switch. I believe a simple stratight-thru cable is right here, but I would have a cross-over AND a rol-over handy just in case. Plug in my test/development server. Can I still see it from my workstation? If not, then debug that one. Try the other cables between the hub and the switch (or as a last desparate measure try the documentation - yuk). The previous response about not using "Auto Negotoiation" on your NICs (and switch ports) is useful here. Once that gets running, I move over myPC. Can I still see the test/dev server? Can I still see other systems on the hub? Debug this.

These 2 pilots then will give you enough information to start moving everything else off the hub to the switch. Oh, one more thing: sometimes I do not move EVERYTHING off the hub. Some users do not use the network too much, so I leave them on the hub. I definitely move servers, routers, the firewall and of course my PC ( ;-] ).

While you do this, document who is plugged into what port.

Later you can try playing around with VLANs, if you think this a worthwhile exercise.

by shanghai sam

As you suggested, I did a test and everything worked fine. The problem was with the large # of machines connecting at the same time, and of course the fact that I had the DIP (here's my sign!) switches wrong. I was using the trucking function to connect the three switches, but instead of having the Dip switches (on the main switch) set for two-2port trunks, I had them set for one-4port trunk. Appearantly this caused some negotiation issues with some of the older cards (not to mention a host of other problems ie. WinSock errors trying to authenticate to the Unix Box on a few machines, and network printers not printing, but they would print a "test page" ok??). All this cleared up by changing the DIP switch. This was the last thingI would have thought since most of the machines on all the switches were working, and I thought I had the Dip switches correct.
In hind site I should have mentioned the fact that I was trunking the switches together.
The fiber issue is an incompatability with the 10Mb fiber hubs and the 100Mb fiber module on the switch. Do you get the feeling this is an old network? 1994.
Thanks for your suggestions.
Paul

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