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Jan 9th, 2007

Network was working perfectly until we introduced a switch!

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Hi there I've never posted to a support forum before so here goes :cheesy:

First of all I'll give you the details of my network and then the problem!

Total PCs: 7 (including 2 laptops which access network wirelessly)
IP Addresses: Handled by DHCP server on router
Router: D-Link DI-524 4-port
Switch: 3Com 8-port switch model 3CFSU08
O/S: Windows XP Pro SP2 on all machines
Internet Connection: ADSL

Now that i've got that out the way (and hopefully included everything you need to know) I'll describe the problem I am facing

Basically our network until about two weeks ago was working fine we then required an extra two desktops so I purchased the above mentioned switch.

Connecting the wires and such I believe went well everything lights up and works.

The problem though is that at any one time on any of the PCs or laptops the connection seems to time out. By this I mean that the connection is there but you cannot access neither the internet or any of the folders that the other PCs are sharing.

To resolve this time out it is necessary to disconnect the network cable and plug it in again or in the case of the wireless network disable the network adaptor and then reenable it.

This problem is driving me nuts! so any help anyone can give me will be GREATLY appreciated!!!

Thanks Guys

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taichi1982

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Jan 9th, 2007

Re: Network was working perfectly until we introduced a switch!

Click to Expand / Collapse Quote originally posted by taichi1982 ...

To resolve this time out it is necessary to disconnect the network cable and plug it in again or in the case of the wireless network disable the network adaptor and then reenable it.

I mean on the PC itself not on the router or switch :cheesy: sorry just reading through my post hehehe

taichi1982

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Jan 9th, 2007

Re: Network was working perfectly until we introduced a switch!

welcome taichi!

Do you have any security enabled on your router?? Also, when you get the limited or no connectivity what IP are you recieving?

Do you have business class ISP, or home?

Duki

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Jan 9th, 2007

Re: Network was working perfectly until we introduced a switch!

What sort of ethernet cable did you use to connect the switch to the router? did you use a crossover or a straight-through?

Do the four ethernet ports on your router allow the router to act as a switch? (In other words, are the workstations who plug directly into the router all on the same network? - I'll assume so, since most home routers seem to work this way)

Usually, this sort of switch-to-switch connection requires a crossover cable, unless the 3Com switch has a specific router uplink port.
(In which case, I'd suggest you connect the router to one of the switch's workstation ports using a crossover cable - using the uplink port on a switch to another switch is always a bad idea)

Last edited by Bench; Jan 9th, 2007 at 11:52 pm.

Bench

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Jan 10th, 2007

Re: Network was working perfectly until we introduced a switch!

Hi Guys!

Right, I do have WEP enabled on the wireless network... Strange thing is that we don't get Limited or no connectivity warning but when the network times out its the same effect.

I used a straight through cable to connect the two together (please tell me thats the problem!) the strange thing is none of the ports specify uplink on them. Very confusing! can anyone check the specifications on the switch (3Com 8-port switch model: 3CFSU08) cause I can't see it anywhere!

In the case where no specific uplink port is specified do I need to use a crossover cable?

Thanks for your patience

taichi1982

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Re: Network was working perfectly until we introduced a switch!

Out of curiousity, what happens to the 3Com switch portion of your network when the connection to the router is removed completely? do the workstations on that switch communicate to each another without timing out?

Your router's ethernet ports will be using the same pin layout as the switch's ethernet ports, and a straight-through cable just isn't appropriate for connecting two matching devices together - the transmit (Tx) pins of both devices will be firing data at each another, leaving the Recieve (Rx) pins idle. A Crossover cable swaps these pins at either end (Hence the name cross-over

). Exactly the same rule applies when connecting two workstations together with a single cable, too.

If, as you say, the lights are on when the cable is connected, then I suspect both devices are confused by being able to detect the presense of another device, but unable to autonegotiate with each another. If each segment of the network works independently without the two devices connected, then its almost certainly the cable.

Last edited by Bench; Jan 10th, 2007 at 8:46 am.

Bench

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Jan 10th, 2007

Re: Network was working perfectly until we introduced a switch!

Cheers Mate! That sounds plausible can't wait to try tomorrow at work

Thanks. I'll let you know what happens... fingers crossed

taichi1982

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Jan 11th, 2007

Re: Network was working perfectly until we introduced a switch!

I would suggest you use a crossover cable between the router and switch also.

reezin14

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Jan 11th, 2007

Re: Network was working perfectly until we introduced a switch!

Right I made a Crossover cable plugged it in (this time I placed all the PCs on the switch rather then some on the router and some on the switch). Now it seems that the network is available i.e can browse My Network Places but the internet is what seems to time out.

On one of the PCs I was browsing normally whilst on another one there was no internet whatsoever.

Isn't there suppose to be a uplink port on the switch? On this particular one it doesn't actually specify which port to plug it in to. Just for safe keeping I plugged the crossover cable into Port 1.

Thanks for your patience

taichi1982

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Re: Network was working perfectly until we introduced a switch!

Click to Expand / Collapse Quote originally posted by taichi1982 ...

Right I made a Crossover cable plugged it in (this time I placed all the PCs on the switch rather then some on the router and some on the switch). Now it seems that the network is available i.e can browse My Network Places but the internet is what seems to time out.

On one of the PCs I was browsing normally whilst on another one there was no internet whatsoever.

Well, that's a good start I suppose - We can be 99% certain that the switch isn't at fault.

Quote ...

Isn't there suppose to be a uplink port on the switch? On this particular one it doesn't actually specify which port to plug it in to. Just for safe keeping I plugged the crossover cable into Port 1.

Thanks for your patience

Some switches do have uplink ports - but the fact you can connect to the internet on even one machine through the switch (And can connect to other workstations on the switch) means that's not the cause of the problem (The switch is doing everything it needs to do - relaying ethernet frames between its interfaces)

Are you able to ping the router's IP address from all the workstations on the switch? and are you able to connect to the router's web interface (or telnet) from each workstation?

If you can connect to the router's web interface from any workstation, that means the physical and logical connections from that workstations to the router are all OK.

You should double-check the IP configuration on each workstation - to ensure that each one still uses a unique IP, and still have their default gateway set to the local IP of the router etc. It may be worth setting static IP's for the workstations, instead of relying on DHCP.

Last edited by Bench; Jan 11th, 2007 at 9:56 pm.

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