[Users] ARP queris being ignored

Denis V. Lunev den at parallels.com
Wed Apr 23 04:45:50 EDT 2008


On Wed, 2008-04-23 at 15:37 +0930, chris at cgb1911.mine.nu wrote:
> Hi All,
> 
> I have been using OpenVZ for a few months now, and I've been having a
> problem with VE's running for longer then a few days - the hardware
> node ignores ARP queries for VE's that are running on it.  The VE has
> IP 192.168.0.105.
> 
> When things are working, I see a line from 'arp -a' for the 192.168.0.105
> host:
>   [root at sonata ~]# arp -a
>   ? (192.168.0.160) at 00:07:E9:5F:BA:60 [ether] on eth0
>   ? (192.168.0.253) at 00:1B:2B:2C:C3:4D [ether] on eth0
>   ? (192.168.0.105) at * PERM PUP on eth0
> 
> When things stop working, the 192.168.0.105 disappears from the output
> of 'arp -a'.  An entry for 192.168.0.105 stops appearing in
> /proc/net/arp as well.
> 
> A tcpdump show the arp query arriving on the hardware node.
>   [root at sonata ~]# tcpdump -nni any arp
>   tcpdump: WARNING: Promiscuous mode not supported on the "any" device
>   tcpdump: verbose output suppressed, use -v or -vv for full protocol decode
>   listening on any, link-type LINUX_SLL (Linux cooked), capture size 96 bytes
>   15:30:19.964806 arp who-has 192.168.0.105 tell 192.168.0.253
>   15:30:21.973385 arp who-has 192.168.0.105 tell 192.168.0.253
>   15:30:23.973453 arp who-has 192.168.0.105 tell 192.168.0.253
>   15:30:25.976838 arp who-has 192.168.0.105 tell 192.168.0.253

you'll have arp replay iff on the _target_ node/VE
ip route get 192.168.0.105 from 192.168.0.253 iif <incoming_device>
will return either a local route or route to a device other than
incoming.

Regards,
	Den



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