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How To Fix Error: kernel neighbour table overflow – Linux

Hi,

If you guys are getting the below mentioned error with the syslog, you can follow the steps mentioned in here to have a fix for it. The error in the syslog will look like below:
kernel: Neighbour table overflow

This problem usually occurs in 2.6X kernels if your node is inside a large network. There is no need to worry, we can fix this very easily.

How to fix kernel neighbour table overflow error?

Check the contents of the following files. You can use any of the file manipulation tool for this, am using ‘cat’ command here:

# cat /proc/sys/net/ipv4/neigh/default/gc_thresh1 # cat /proc/sys/net/ipv4/neigh/default/gc_thresh2 # cat /proc/sys/net/ipv4/neigh/default/gc_thresh3

By default the values will be 128, 512 and 1024 respectively. Please check the below screenshot for more information.

To change the them to 512, 1024 and 2048, please do run the following commands.

echo 512 > /proc/sys/net/ipv4/neigh/default/gc_thresh1 echo 1024 > /proc/sys/net/ipv4/neigh/default/gc_thresh2 echo 2048 > /proc/sys/net/ipv4/neigh/default/gc_thresh3

These changes will remain until the next reboot. To make the changes permanent, add the following lines to your /etc/sysctl.conf file.

net.ipv4.neigh.default.gc_thresh1 = 512 net.ipv4.neigh.default.gc_thresh2 = 1024 net.ipv4.neigh.default.gc_thresh3 = 2048

That’s all guys, this can probably fix the error. Thank you for reading! Please visit nixlinux again! Write comments as we love to hear from you!

Bye!

Jishnu KS

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