====== Operation in PPPoE/PPTP/L2TP/IPIP/GRE (including ERSPAN) tunnels ======
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<note important>By default, DPI does not parse tunnels (tagged VLAN/QINQ and MPLS traffic are not considered tunnels), since tunnels may carry traffic from different operators or customers with conflicting IP sets. However, in non-standard deployments (before BRAS), tunnel parsing is required.</note>

In the Lawful Interception prefilter, tunnel parsing is enabled automatically when the ''tap_dev'' parameter is present.\\
In other cases, tunnel parsing must be explicitly enabled using a configuration parameter in the file ''/etc/dpi/fastdpi.conf'':

<code bash>
check_tunnels=1
</code>

This parameter enables parsing of PPPoE/PPTP/L2TP/IPIP/GRE (including ERSPAN) tunnels.