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Neighbor Table Overflow

July 18, 2011 • Customer Services       

Synopsis

Article

If you have walked past your console and seen reports of a Neighbor Table Overflow, it means that your CensorNet has seen more MAC addresses than it is currently configured to cope with.

To fix this problem, type these commands at the command prompt, one after another

echo 1024 > /proc/sys/net/ipv4/neigh/default/gc_thresh1
echo 2048 > /proc/sys/net/ipv4/neigh/default/gc_thresh2
echo 4096 > /proc/sys/net/ipv4/neigh/default/gc_thresh3

These commands will take effect immediately and ensure that you don't suffer those messages again, at least until the next time you reboot.

To ensure these values get set again on the next reboot you should log into the command line as root and perform these commands :-

cd /etc/init.d
nano networking

Then type

Ctrl-W start)

This should put your cursor on the first line of the following block

start)
process_options
log_action_begin_msg ""Configuring network interfaces""
if ifup -a; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
;;

Insert the commands above after the fi, but before the ;; so that the modified block reads

start)
process_options
log_action_begin_msg ""Configuring network interfaces""
if ifup -a; then
log_action_end_msg $?
else
log_action_end_msg $?
fi
echo 1024 > /proc/sys/net/ipv4/neigh/default/gc_thresh1
echo 2048 > /proc/sys/net/ipv4/neigh/default/gc_thresh2
echo 4096 > /proc/sys/net/ipv4/neigh/default/gc_thresh3
;;

Ctrl-O and RETURN to write the file
Ctrl-X to exit the editor

Now, these new values will be set every time your system starts.

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