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How to resolve LAN/Network problems?

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by rayfoxxe

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Ok here's the thing. We're managing a wide network of computers all running on Windows XP SP3. Our network consists of, starting from the internet modem device, then splits the connection with a switch hub which is connected with a router which is then connected each room that has one 8 port hub with 10 rooms having computers, totaling to 10 hub units. But those 10 hubs are lined to another hub from the next room over. So basically we made them branch out to reach the other rooms (example: Hub 1 directly connects to the net modem, Hub 2 is connected with Hub 1, and Hub 3 is connected with Hub 2, and so on). We're having some sort of connection problem where a computer would get disconnected from the network for a while, then it gets connected again even if we did nothing. We ruled out possible line and hardware damage and viruses are kept at bay. The router and hubs are working fine, the ports are not dirty or loose, and the LAN cables are alright, no tearing or damage whatsoever on the line and no damage to the RJ plug. The LAN cards/devices on the computers are working perfectly and have no problems. But the disconnection issue with some of the computers still persists. What can be other causes of this? And how could it be resolved?

12 replies

by oh smeg

What do the computers get disconnected from?

Is it another computer or the Internet?

If it's Internetrnet have you looked at the Router/Modem and made sure that it's not set to a lower number of concurrentrent connections than the number of attached computers?

What is giving the IP Addresses here? And are you sure that the Supported IP Range is big enough for the computers in use?

If it's that the computer is being disconnected from another computer on the Network you need to remember that XP Pro only supports 10 Concurent Connections at a time and XP Home only supports 5, so if you are trying to have more than 5/10 devices connect to one computer at a time XP can not support this.

Col

by rayfoxxe

They get disconnected from the network, not only that, the computers gets disconnected from shared printers and devices on the network. Sometimes they also get disconnected from the internet, but there are no warning signs that the network is disconnected. It just doesn't connected with the network and pretty much either doesn't browse the internet, cannot access shared objects, and cannot send messages VIA-IP Messaging. We set the computers on static IPs ranging from 192.168.1.1 to 192.168.1.255, and there are only less than 60 computers on the network. We've checked the router, it's working fine. Only about 2 - 5 computers gets disconnected at any time during the day. And we're running on XP Pro SP3.

by ---tk---

Some things to think about... Are all the PC's that "disconnect" the same, or different every time? Also when the PC's disconnect is it late in the week and or day? When they disconnect does the NIC disappear or is it like the network cable was unplugged? Have you checked out the event logs?

Are you actually using hubs or unmanaged switches? If they are truly hubs; upgrade them to unmanaged switches that can retain a MAC table (min). I would also start creating IP reservations on the DHCP server, and setting static IP's locally on each PC. Setting everything to static should help reduce network chatter. To much "chatter" can overload oldish switches...

Best of luck!

by rayfoxxe

They disconnect at different times and on different computers at any point of time during the day. But a couple of same computers does disconnect every once in a while, but we checked those units and they don't seem to have a problem with its hardware or software, it's really just the network. And we're using one main switch that's managed and about 10 hubs for different offices with around 2 - 8 computers in each department.

by djcjwags

Couple observations.

Use switches instead of hubs... Like yesterday.

Are the problem pcs always connected to the same hub? Maybe the hub is flakey. Try a different device. Is power an issue? Try a ups on the hubs.

Are the shares just on the pcs? Do you have a server?

by vpelite

Ideal setup: Modem - Router - Hub - Hubs
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Okay, your problem is collisions CSMA/CD. "Basically, a collision domain is a network segment that allows normal network traffic to flow back and forth. In the old days of hubs, this meant you had a lot of collisions, and the old CSMA/CD would be working overtime to try to get those packets re-sent every time there was a collision on the wire (since ethernet allows only one host to be transmitting at once without there being a traffic jam). With switches, you break up collision domains by switching packets bound for other collision domains. These days, since we mostly use switches to connect computers to the network, you generally have one collision domain to a PC."

by vpelite

Ideal setup: Modem - Router - Hub - Hubs
----------------------------------------------------------
Okay, your problem is collisions CSMA/CD. "Basically, a collision domain is a network segment that allows normal network traffic to flow back and forth. In the old days of hubs, this meant you had a lot of collisions, and the old CSMA/CD would be working overtime to try to get those packets re-sent every time there was a collision on the wire (since ethernet allows only one host to be transmitting at once without there being a traffic jam). With switches, you break up collision domains by switching packets bound for other collision domains. These days, since we mostly use switches to connect computers to the network, you generally have one collision domain to a PC."

by vpelite

You may have IP address conflicts. Just disable the port and turn it back on again. This isn't ideal but, a work around the hubs or simply upgrade to a switch like previously mentioned.

by vpelite

You may have IP address conflicts. Just disable the port and turn it back on again. This isn't ideal but, a work around the hubs or simply upgrade to a switch like previously mentioned.

by dylan teo

Sometimes, the setting will turn off unused ports. Besides that, check also the physical cable length. Each cable 5e should not exceed 100m. But hubs does not take advantage of better cable grade. I am assuming your hub is a 10 share. There is a chance there are too many collisions on port the switch connecting to your hubs. The switch will shut down the port .

by drroysingh

Looks like you have one big colision domain on your hand.

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