UnixServerAdmin

Server Administration & Management

Neighbour table overflow

you may get this error in  dmesg

Neighbour table overflow.
printk: 402 messages suppressed.
Neighbour table overflow.
printk: 367 messages suppressed.
Neighbour table overflow.
printk: 394 messages suppressed.
Neighbour table overflow.

Kernel will thow this warning messages when the ARP cache overflows. You need to increase the size of  ARP cache to get rid of this error. Just increase the value of hard and soft limit in the following files:-

# echo 2048 > /proc/sys/net/ipv4/neigh/default/gc_thresh3

This file contains the hard maximum number of entries to keep in the ARP cache. By default the entry will be 1024

# echo 1024 > /proc/sys/net/ipv4/neigh/default/gc_thresh2

This file contains the soft maximum number of entries to keep in the ARP cache. Default value is 512

When you reboot the server, the values will be automatically reset to the default one. To prevent this ad the following  in the file  /etc/rc.d/rc.local

# echo 2048 > /proc/sys/net/ipv4/neigh/default/gc_thresh3

# echo 1024 > /proc/sys/net/ipv4/neigh/default/gc_thresh2

That’s it.

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July 31, 2012 - Posted by | Tips & Tricks, Unix/Linux | , ,

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