[CentOS] How does Linux choose ARP request source IP?

Sven Kieske svenkieske at gmail.com
Sat Mar 21 12:37:14 UTC 2015


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On 20.03.2015 14:38, Chris Adams wrote:
> I'm looking into some network "weirdness", and I noticed that a
> CentOS 6 system with multiple IP addresses (load balancer running
> keepalived) is sending ARP requests from apparently random source
> IPs.  I would have thought that ARP requests would always come from
> the interface's "primary" IP (especially since keepalived adds all
> the virtual IPs with a /32 mask).
> 
> This is probably not related to my problem, but I just thought it
> was odd.  Is there a way to control this?

You may be running into the "arp flux" problem:

http://blog.cj2s.de/archives/29-Preventing-ARP-flux-on-Linux.html

HTH

Sven
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