Friday 8 March 2013

Kernel: Neighbour table overflow


Nearly any linux 2.6.* kernel. Typically occurs in situations where there are large, flat networks (e.g. when the subnet mask is /16 and there are more than 1000 active nodes). Solution

1. Check current values:
# grep . /proc/sys/net/ipv4/neigh/default/gc_thresh*

2. Echo new (higher) values into each of the above /proc entries:
# echo 512 > /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

3. Add the same values to /etc/sysctl.conf:
# net.ipv4.neigh.default.gc_thresh1 = 512
# net.ipv4.neigh.default.gc_thresh2 = 2048
# net.ipv4.neigh.default.gc_thresh3 = 4096

Refer this link - https://supportcenter.checkpoint.com/supportcenter/portal?eventSubmit_doGoviewsolutiondetails=&solutionid=sk43772