Losing all network connections in a small network with a hub.

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Networking
Configuration: a small network with a dual-speed hub (10/100) and some Windows PC?s. Sometimes I lose the connections to all devices on this network. Ping won?t see the other hosts. All I have to do is disconnect and reconnect the network cable and everything is working again. Same problems with a different PC, with a different OS (2000+XP), with another dual-speed hub. Any idea what could be the reason? The reason to keep a hub against a switch is to analyse all traffic for development and problem solving.

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How is your IP addresses setup, Static or DHCP? If DHCP what device is supplying the IP addresses? Could you monitor your network activity via network monitor added to your nic and viewing network activity in your task manager?
What does command “ipconfig /all” indicate for information while the computer has lost connectivity?

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  • Programmers
    I'm using static IP addresses so ipconfig will show the same information. I have a DHCP server (Thomson Speedtouch ADSL) only used for my portable computer. Some weeks I don't have any problems and then one day it happens twice a day. When it happens with one PC, the others are still working fine. Good tip, I will check next time for network activity and look for increasing packets on the nic.
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  • Bobkberg
    I'd also suggest that you make sure everything is on a good quality surge protector (APC, Tripp-Lite, Belkin). I've also had curious results with some of the dual-speed hubs (which I also use for traffic capture) when not all devices are 100 Mb capable. If the surge protector route doesn't help, try manually choking every system down to 10 Mb and see if that makes a difference. Bob
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  • MayankT
    THe problem here seems to be pretty much of the traffic congestion on the Hub. We know that Ethernet works on the base principle of collusion (or collision) Domain. Now if there would be a instance of collusion in the network the HUb would become defunt and nothing would work. To check you issue see if there is a constant Orange light glowing. I guess there could be the issue as you are saying the cable reset corrects the problem. If this is the constant problem I would suggest you to move on a switched network and phase off the Hubs
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  • Backbyrner
    I've experienced this problem before a number of times. In those cases there were three separate causes. The first was a faulty Cat5 cable that was dropping packets intermittently and would "go walkabout" for a while. The second was a faulty hub, again an intermittent fault that increased in frequency until it finally died. The third was related to the auto negotiation of speed (10 vs 100 mbps). If the cabling is not fully Cat5-compliant the speed may alternate between the two speeds frequently leading to timeouts. A way around this is to nail down one end to either 10 or 100 mbps. This is probaly easier done on the hub (assuming it is manageable). Good luck!
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  • Applications
    Some times it happens frequently that your network connection with some pc's fails. Check out changing the NIC with other one. The display adaptor resources (I/O) range may clash with the NIC resources. This may be the reason that the network connection fails. Another thing is that try adding NetBEUI Protocol. This will definately help you if there is no conflicts with the pc's display adapter and the NIC. Chetan
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  • Larrythethird
    You didn't say what make and model of hub you're using. Just by stating that you are using a hub, it is probably something that's been around for a while. Most of my issues like this are when one PC or workstation, for some reason, changes speeds. On most hubs, although they are dual speed, that will only do one or the other, not 10 and 100. Either 10 or 100. This can cause negotiation problems with established connections. I agree with one of the posts above, set everything on the hub to 10 full. No more negotiation. I can sort of understand the issue with wanting to see all of the packets for developement as to why to keep the hub, but a low cost switch and a good packet analyzer should be able to do the same thing. For my in-house network and performance issues, we have installed taps on all of the important links and just move the analyzer to where we need it.
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  • Mark2006
    Hubs do not translate 10Mb traffic to 100Mb traffic. What is happening is a PC auto negotiates to 10Mb while the other PC's are on 100Mb. The best solution is to decide on the Speed either 10 or 100Mb then set it on all PC's network cards. Another solution would be to use a switch and configure all traffice to forward to the port where your snifer is attached.
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