====== Termination at the autonomous system (AS) level ======
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Starting from the VAS Experts DPI version 7.4 the traffic termination feature applicable only for explicitly specified AS is added.
To enable this feature you need to specify following option in fastdpi.conf
<code>
   # To enable termination at the autonomous system level
bras_term_by_as=1
</code>
and [[dpi:dpi_options:opt_priority:priority_config_as|prepare the asnum.dscp file]]: all the AS for which traffic termination is allowed are marked with a special keyword '' term ''.

<note important>By default, the AS termination mode is disabled (''bras_term_by_as=0'')</note>

The AS termination mode affects the L2 BRAS operation in the following way:

[[dpi:bras_bng:bras_l2_options:bras_l2_vlan_ipsg|IP source guard]]: is used only if the AS is marked as ''term'' for the IP packet source.
If the autonomous system to which the IP source belongs is not marked as '' term '' then the IP source guard will not be applied to such a package.

[[dpi:bras_bng:bras_l2_options:bras_l2_vlan_local|Local traffic interconnection]]: Both IP addresses (source and destination) must belong to the autonomous system marked as '' term ''. If at least one of the AS is not marked as '' term '' then the local traffic interconnection will not take place.

[[dpi:bras_bng:bras_l2_vlan_term|Outgoing traffic termination]] is performed only if the AS for the source IP is marked as ''term''. For incoming traffic, interconnection is performed only if the AS for the destination IP (the gray one, i.e. besides the NAT) is marked as '' term ''.

<note>Termination at the AS level allows, inter alia, to apply the BRAS L2 features step by step, in fact by subnets, so you can allocate a subnet of your local network to a separate AS and assign the ''local'' and ''term'' flags just for it. After integrating L2 BRAS with your hardware on this dedicated subnet and corresponding troubleshooting, you can add the next subnet to this AS marked as ''term'', etc.</note>