Duplicate IP Error

[pingu]

Hi,

We have recently had our network rebuilt by a contractor from a messy, unmanaged, plate of spaghetti to a managed, neat, workhorse. Unfortunately since then, nothing works properly anymore.

Anyway, in trying to track to the causes of some of the issues we are having we have come across something odd that we think may point to a solution.

All of our 10.4.x machines (including servers) are now continuously complaining of a duplicate IP address in use. The odd thing is that the MAC address they report as using this address is their own. Does anybody know of a bug or incompatibility that may be causing this? We are using HP Procurve switches (4160gl, 2824, 2848, 2626)

For example my machine: –

G5, 2GhzDP 1.5GB, 10.4.7. IP 10.1.1.198, MAC 00:14:51:11:58:86

system.log from this morning: –

[code]
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:07 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:08 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:13 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:13 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:13 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:16 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:16 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:40:16 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:51:56 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:51:56 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 10:51:56 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:00:16 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:00:16 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:00:16 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:00:44 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:00:44 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:00:44 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:01:33 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:01:33 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
Nov 29 11:01:33 CP-IT-01 kernel[0]: en0 duplicate IP address 10.1.1.198 sent from address 00:14:51:11:58:86
[/code]

[s.Oliver]

hi there,
you’re not alone. i see this error message at (just) one place, where an PM G5 Dual 1.8, equipped with an additional APPLE ethernet gigabit card, runs Mac OS X Server.
Nov 29 23:31:16 mail kernel[0]: bond0 duplicate IP address 192.168.1.5 sent from address (own MAC address)
the errors were at least there, since 10.4.7, cause i updated yesterday to 10.4.8. bang, had bad luck with password server not working afterwards. apple had a knowledge base article, which helped to fix this. even though, i had to modify that script, cause of network differencies.
well, at that client the setup is as follows:
server is connected via 2 network cables to a netgear gigabit switch. the setup for the network is changed, so that i have a new network interface called bond0, as apple recommends it. so the server has the (theoretically) double network throughput. there’s no need to change anything on the switch – apple says.
at another client of mine, a Xserve uses the same setup as above, with the only difference in being, that the netgear gigabit switch is set to bind those two ports, where both network cables from the Xserve coming are connected to, to one port. at this place no such errors occur.
at the client plotted as first one here, i was not successful in combining those two ports at the netgear switch. the switch doesn’t accept the bonding, why ever that is. i tried all to my knowledge.

[black_box]

I also experienced this exact issue.

Out of the blue, all of our Macs (we run a mixed environment shop here) were showing this exact message.

[code]en0 duplicate IP address 10.10.10.X sent from address (their own mac address)[/code]

Since this was happening to *all* of our Macs (with in the same switch), we figured the problem was either the switch, or one of the Macs plugged into the switch. (the other windows and unix boxes connected into the same switch were unaffected)

We tried to track down the problem, realizing that if we moved the “trouble” Mac from its current switch, into another switch the problem would go away, the second we’d place the cable back into its previous switch the problem would reoccur.

We we’re never able to track down the issue. We simply moved all the troubles macs out of that switch and into another. We figured if we moved *all* the Macs into the new switch, the problem might follow, assuming the problem was with a specific computer.

The problem didn’t follow as we expected. This lead us to believe the problem was with the switch. We ended up moving the Macs back into the old switch (with no changes besides physically moving their cables) and the problem never returned.

So to this day, we’re still at a loss. No network setting were changes, no link aggregation settings changed, nothing.

Anyone have any ideas?

[pingu]

We finally managed to track down the problem. It looks like it was a mis-configured trunk between one of the perimeter switches and the core switch. We ‘are not sure exactly what was wrong with the config, but it looks like it may be that the network company only configured one end of it.

Since we disconnected three out of the four cables that made up the trunk all the errors seem to have gone away, our server seems to have stabilised and our network is a whole load faster and more reliable.

Dan

[premiermac]

Did you turn on RTSP aka Rapid Spanning Tree Protocol on the switch? That’s required for using trunks.

[Author]

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