Re: Linux ARPD -- neighbor table overflow

[Chris Doyle <umaro () narshe net>]

I have had the same kinds of problems, but on a linux router routing about 3 class Cs or more.. It was a quick hack, 
but I just put this in my startup scripts:

echo 8192 > /proc/sys/net/ipv4/neigh/default/gc_thresh1
echo 8192 > /proc/sys/net/ipv4/neigh/default/gc_thresh2
echo 8192 > /proc/sys/net/ipv4/neigh/default/gc_thresh3

which doesn't actually fix the problem, it just makes the treshhold higher.

I haven't noticed any slowdown because of the higher threshhold, though.

I would certainly be interested in any actual fix, but this worked for me.

Cheers
Chris Doyle

On Thu, 18 Mar 2004 17:12:07 -0600
"Jeff Adam" <jadam () seark edu> wrote:

> I have run into a problem recently with arp table size limitation in the Linux kernel.
>
>  
>
> A bit of History
>
>  I have been using the same box as a firewall for past couple of years and it has performed flawlessly Linux 2.4 / 
> iptables but every couple of months the number of nodes on the LAN increases by 20 to 60 usually on the high end of 
> that range we are already beyond 500 computers approaching 600 with plans to add 40 to 60 additional computers 
> already being discussed. We have recently developed a problem with neighbor table overflows on the firewall during 
> peak hours.
>
>  
>
> I believe I have the problem repaired I recompiled the kernel with arpd support and netlink and installed arpd and 
> made some changes in /proc
>
> Some other issues developed with arpd that were unexpected
>  
>
> the problem is all of the documentation I found on arpd was rather dated including one written in  2001 that claimed 
> the package (arpd) was far beyond abandoned by the upstream maintainer. im sure networks with more than 256 nodes are 
> not that uncommon. My question is what experiences have other readers of the list had with this issue and what other 
> solutions are there besides arpd for this issue.
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