Network switch Issues

[lnbarnes]

Hi,

I have been having some very strange network switch issues. I have a solid IT background of 14 years in total but i have to say this problem has stumped me for the time being. I installed a Micronet 24-Port switch into a business about 4 months ago and this has been working just fine until recently.

This switch connects at this stage 11 PC's, 1 Billion ADSL modem/Router and 1 network printer. When using this switch i cannot get any IP addresses from the router which is configured as a DHCP server. All the PC's on the LAN report low connectivity issues and never recieve an IP address. If i assign a static IP address to a PC i still cannot ping the router.

I have tried lots of different network cables, different ports on the switch and the router to no avail. If i connect a PC directly to the router as it has a four port switch built in the PC gets an IP address and connects to the internet etc. This confirms that the router is working fine. I also have an older 8 port switch and if i use this it also works ok. I have tried 3 different 24port switches now and none of them will work (these were also different brands) I have also tried another power outlet for the switch)

I should also add that the 3 24 port switches all tested ok at other locations.

I am at a loss now what to test.

Does anyone have any ideas on this bizare fault?

Please help

Kind Regards
Lawrence

 

[JCLW]

Try a cross-over cable between the router and switch?
(or a straight cable if you've got a cross-over currently)

Update the router's firmware?

And to the forums!

 

[lnbarnes]

Hi JCLW,

Firstly thanks for your assistance.

It should not need a cross over cable, but certainly worth a try. It is using a straight over cable at this stage.

The router's firmware is upto date. It is actually a new router also. The LAN connection kept getting dropped so i replaced the router but now i wonder if that was actaully the fault.

Regards
Lawrence

 

[TempliNocturnus]

A crossover is used to connect two routers, or two switches, or two PC's; like devices.

Have you tried creating a management VLAN and pinging it from elsewere on the network? Are the LED's for the interfaces green?

 

[lnbarnes]

I have not tried a cross over cable as yet. This does not explain why the 24 port switch has been working for 3 months prior and also why i can connect both an 8 port and 5 port switch to the router without cross over cables and this has been working for the last 2 days as a workaround. The only difference is that the 24 port switch will not work. but when i use an 8 port, 5port etc all is fine.

It is almost as if their is not enough power to run the 24 port switch or load or something.



How do i create a management VLAN?, and yes the interfaces are green on the switches and on the router.

 

[TempliNocturnus]

I was implying that a crossover is useless for hooking a switch to a router. Have you updated the switches firmware? Maybe the switch broke and needs to be replaced? As for making a management VLAN, I'm not familiar with the brand equipment you're using so I couldn't tell you exactly, but I would assume with an IT background of 14 years, you'd be more than capable of figuring it out. Being able to ping the management VLAN might be able to tell you whether the switch is bad or whether something is misconfigured. I'd assume a switch with 24 ports would be managed, but I can't be certain; maybe your switch is not managed.

 

[ErikD]

Not all 24 port switches are managed, there are some unmanaged ones floating around. So the first question would be, as I have also never worked with that brand, is if the switch is indeed a managed switch? If not you will never be able to create a management VLAN to ping.

Any LEDs on the switch that indicate some kind of fault or abnormal operation? Generally you will have a green link light when something is connected to it. Are you getting a good connection between the router and switch? That would seem to be the most likely problem. Different uplink ports tried between them? And a crossover cable won't help as mentioned it is only for connecting like devices. Router to switch you use striaght.

 

[NWEng]

If you are still having the problem, at this point I'm more inclined to think there's more going on with the PC's/servers than you're aware of. I would connect them one by one until the problem recreates itself, and investigate from there. (Unless you have a Sniffer, then it's real easy.) It sounds like almost everything else has been eliminated or replaced with the same results.

 

[lnbarnes]

Good news,

With the help of a friend over the weekend managed to find the problem

Oddly enough it was the Billion ADSL modem/Router. We reset the modem back to factory defaults and then tested, all now working ok. The router is once again assigning the IP addresses when connected to the 24 port Micronet switch. Very bizare that this worked when connected to the older 8 port switch in the cabninet but not when connected to the 24 Port. The only thing we can think of it has something to do with the MAC addresses from the PC's stored on the Billion's router table. Who knows, the main thing is all
now seems to be ok again.

Oh and by the way it was an unmanaged 24 Port Micronet Switch. Nothing fancy at all, just plug and pray

Thanks for everyones help on this.

Lawrence