====== PFSense - Troubleshooting - mbuf full ======

An mbuf is a basic unit of memory management in the kernel IPC subsystem.  Network packets and socket buffers are stored in mbufs.

Try increase **nmbclusters**.

Navigate to **System -> Advanced -> System Tunables**.

<code>
kern.ipc.nmbclusters=65536
</code>

or SSH in and type:

<code>
sysctl kern.ipc.nmbclusters=65536
</code>

<WRAP info>
**NOTE:**  You should also make the appropriate changes to /boot/loader.conf.local in order for the change to persist across reboots.

Reboot to make this change stick.

The actual value for **nmbclusters** depends on the the number of network interfaces, CPU cores, and few other factors - a bit of experimenting is required to find the optimal value for each system.
</WRAP>