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I have a fleet of VPS servers, each have two /27's running to it. On only one of the machines, a set of VPS's on a particular subnet drops connection for 5-10 minutes at a time to the internet. The VPS themselves do not crash, just networking drops but returns after some time.

These are in bridged mode so no tricky routing going on. I have had our datacenter check and double check routes and they claim there is no issue (so please don't tell me to have the DC check at this time) I literally have 20 other nodes in this exact same config without issue.

The other /27 routed to this server has had zero issues and as mentioned and it's only 4-5 VM's on the other subnet that have the issue. I'm investigating this issue more as I await any reply on here to help.

Let me know if any particular log files or similar will help anyone.

As for the datacenter, this was their reply:

The X.X.X.X/27 IP block is routed as a secondary block to the Vlan as it should be. The gateway for the X.X.X.X/27 IP block is X.X.X.X (it was right). Also, I confirmed that there are no overlapping routes for this block that might have been given to another customer. From what I can, the router is configured properly for this subnet. Typically, when single IPs are having issues like this, it is usually caused by some sort of server side configuration. Unfortunately, I am not too familiar with Xen to know what might be causing the issue. However, seeing as this is intermittent, I would definitely suspect a server side configuration issue over a network configuration issue.

Thanks!

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1 Answer

There is an ip conflict on that subnet with that host ip address. I'd bet my life. :)

check arp tables on other hosts that know that IP address. Look closely through all host configurations. See if there is a network interface that has an IP address on the port but not in the configuration files.

Then again... I could be wrong.

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that's what i keep thinking... I just got this reply –  jemmille Nov 17 '10 at 17:44
    
added the DC reply to my post, wouldn't fit here. –  jemmille Nov 17 '10 at 17:50
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