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IP conflict on my small network 2

By rrsuj ·
I have a small network with 10 pc. The broadband line is connected to a small router (IP: which has 4 ports. One port is connected to one pc which has ip addr and another port is connected to a hub with 9 pcs. The other 2 ports are free. All of my computers have different host name and static ip (previously they had same host name). Now some of my computers show the ip conflict message. I did arp -a command to look for the problem in one of the affected pc. The physical address information do not remain same in every arp -a command, it sometime shows the real mac addresses of other computers, sometime it shows an specific mac address at the place of physical address information of several computers. After deleting the ARP cache I ping all other computers to feed the arp cache. But the problem remains same. I cannot figure out why the mac address is different than the original one in the arp result and why I get the ip conflict message very often in several computers. So what is the possible problem? How can I fix it to get all time internet connection in all PC?

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Two problems

by robo_dev In reply to IP conflict on my small n ...

The router has a four port ethernet switch built into it. The forwarding database of that device is what stores the mac addresses.

Either that device is malfunctioning, the database is becoming corrupted, or it is not designed to accomodate 11 PCs.

Is it really a hub or an ethernet switch that the 9 PCs are plugged into?

Check to make sure that the speed/duplex settings are correct for each PC adapter.

If it is actually a hub, then the speed settings of the adapters must be either 10Mbs HALF duplex or 100MBS half duplex.

If it is a switch, they can be full duplex.

If the speed or duplex settings are wrong, excessive CRC errors may corrupt the forwarding database in the ethernet switch, and cause it to have to continually purge the database, resulting in odd problems.

Also make very sure that the hub has connected to the ethernet switch at the correct speed and duplex settings. This may not be possible with an unmanaged device.

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by rrsuj In reply to Two problems

I figured it out. The router has no support for too many devices. Now the problem is solved.

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Change the static addresses

by vivpen In reply to IP conflict on my small n ...

I suggest you start at or above for your static addresses as your router DCHP Server will allot the lowest number available in the range of numbers allowed for DCHP. There should then be no conflicts. In your router DCHP Server set up as many of the MAC addresses with matching IP at it allows depending on your router this will let you set up 5 to 10 addresses.

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