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* Neighbour table overflow.
@ 2004-10-26 17:39 Dominik Karall
  2004-10-26 21:23 ` Chris Wedgwood
  2004-10-26 21:52 ` Ernst Herzberg
  0 siblings, 2 replies; 9+ messages in thread
From: Dominik Karall @ 2004-10-26 17:39 UTC (permalink / raw)
  To: Linux Kernel ML

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can anybody explain why i get thousands of "Neighbour table overflow." 
messages? i didn't get such ones with older kernels (~2.6.6).
here is a dmesg output:

printk: 54050 messages suppressed.
Neighbour table overflow.
printk: 10403 messages suppressed.
Neighbour table overflow.
Neighbour table overflow.
Neighbour table overflow.
Neighbour table overflow.
Neighbour table overflow.
Neighbour table overflow.
Neighbour table overflow.
Neighbour table overflow.
Neighbour table overflow.
Neighbour table overflow.
printk: 58524 messages suppressed.

this couldn't be ok, or?

best regards,
dominik

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^ permalink raw reply	[flat|nested] 9+ messages in thread
* Re: Neighbour table overflow.
@ 2004-10-28  2:25 John Pearson
  0 siblings, 0 replies; 9+ messages in thread
From: John Pearson @ 2004-10-28  2:25 UTC (permalink / raw)
  To: linux-kernel; +Cc: Dominik Karall

You may also be the 'victim' of a poorly configured router.

Out-of-the box, Cisco routers come with proxy ARP enabled;
they will reply to ARP requests for any IP they can route,
that isn't routed via the interface they receive an ARP 
request on.  This makes them more 'plug-and-playful' for 
equipment that talks IP, but doesn't understand routing
(assuming any still exists).

Check the output of
  arp -an
and see if there isn't a single MAC accounting for the lion's
share of your ARP cache.  If there is, seek and destroy^H^H^H^H^Hfang


On Wed, Oct 27, 2004 at 02:30:32AM +0200, Dominik Karall wrote
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> On Wednesday 27 October 2004 01:06, David S. Miller wrote:
> > On Wed, 27 Oct 2004 00:11:26 +0200
> >
> > Dominik Karall <dominik.karall@gmx.net> wrote:
> > > On Tuesday 26 October 2004 23:52, Ernst Herzberg wrote:
> > > > On Tuesday 26 October 2004 19:39, Dominik Karall wrote:
> > > > > can anybody explain why i get thousands of "Neighbour table
> > > > > overflow." messages? i didn't get such ones with older kernels
> > > > > (~2.6.6).
> > > >
> > > > Do you set a default gateway?
> > >
> > > yes, default gateway is set to our server.
> >
> > Do you use a large subnet mask?  For example /16 or /8 or
> > something like that?
> >
> > If so, you will need to bump up the neighbour table garbage
> > collection thresholds under /proc/sys/net/ipv4/neight/default/
> > Specifically gc_thresh1, gc_thresh2, and gc_thresh3
> >
> > You probably have a huge number of machines on your subnet.
> 
> the subnet mask is set to 255.255.0.0, and there are machines from 172.16=
> .0=3D
> =3D2E1=3D20
> to 172.16.1.254. but not all ips are reserved. there are "only" about 100=
> =3D20
> machines in the network.
> i will try to change the values of gc_thresh*, maybe it helps. thx!
> 
> dominik
> 
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^ permalink raw reply	[flat|nested] 9+ messages in thread
end of thread, other threads:[~2004-10-28  2:26 UTC | newest]

Thread overview: 9+ messages (download: mbox.gz follow: Atom feed
-- links below jump to the message on this page --
2004-10-26 17:39 Neighbour table overflow Dominik Karall
2004-10-26 21:23 ` Chris Wedgwood
2004-10-26 22:10   ` Dominik Karall
2004-10-26 21:52 ` Ernst Herzberg
2004-10-26 22:11   ` Dominik Karall
2004-10-26 23:06     ` David S. Miller
2004-10-26 23:58       ` Wichert Akkerman
2004-10-27  0:30       ` Dominik Karall
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2004-10-28  2:25 John Pearson

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