ARP table overflow tuning: Difference between revisions
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{{Portal|User}} | |||
{{Portal|Deployment}} | |||
{{Portal|Network}} | |||
By default, the maximum number of entries that the ARP table can store is set to 1024. | By default, the maximum number of entries that the ARP table can store is set to 1024. | ||
In case of a virtualization configuration with more than 1024 nodes '''on the same ethernet network''', this limitation will be reached. | In case of a virtualization configuration with more than 1024 nodes '''on the same ethernet network''', this limitation will be reached. | ||
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Choose one of the following: | Choose one of the following: | ||
* Using the <code>proc filesystem</code> | * Using the <code>proc filesystem</code> | ||
echo 4096 > /proc/sys/net/ipv4/neigh/default/gc_thresh3 | |||
echo 2048 > /proc/sys/net/ipv4/neigh/default/gc_thresh2 | |||
echo 1024 > /proc/sys/net/ipv4/neigh/default/gc_thresh1 | |||
* Using <code class="command">sysctl</code> | * Using <code class="command">sysctl</code> | ||
/sbin/sysctl -w net.ipv4.neigh.default.gc_thresh3 = 4096 | /sbin/sysctl -w net.ipv4.neigh.default.gc_thresh3=4096 | ||
/sbin/sysctl -w net.ipv4.neigh.default.gc_thresh2 = 2048 | /sbin/sysctl -w net.ipv4.neigh.default.gc_thresh2=2048 | ||
/sbin/sysctl -w net.ipv4.neigh.default.gc_thresh1 = 1024 | /sbin/sysctl -w net.ipv4.neigh.default.gc_thresh1=1024 | ||
* Setting it up definitively editing the <code class="file">/etc/sysctl.conf</code> configuration file and adding: | * Setting it up definitively editing the <code class="file">/etc/sysctl.conf</code> configuration file and adding: | ||
Latest revision as of 17:39, 20 April 2009
By default, the maximum number of entries that the ARP table can store is set to 1024. In case of a virtualization configuration with more than 1024 nodes on the same ethernet network, this limitation will be reached.
Linux offers the possibility to overcome this limitation using the sysctl interface.
Choose one of the following:
- Using the
proc filesystem
echo 4096 > /proc/sys/net/ipv4/neigh/default/gc_thresh3 echo 2048 > /proc/sys/net/ipv4/neigh/default/gc_thresh2 echo 1024 > /proc/sys/net/ipv4/neigh/default/gc_thresh1
- Using
sysctl
/sbin/sysctl -w net.ipv4.neigh.default.gc_thresh3=4096 /sbin/sysctl -w net.ipv4.neigh.default.gc_thresh2=2048 /sbin/sysctl -w net.ipv4.neigh.default.gc_thresh1=1024
- Setting it up definitively editing the
/etc/sysctl.confconfiguration file and adding:
net.ipv4.neigh.default.gc_thresh3 = 4096 net.ipv4.neigh.default.gc_thresh2 = 2048 net.ipv4.neigh.default.gc_thresh1 = 1024
See man 7 arp for more info on the meaning to the gc_threshX sysctl.