====== Priority assignment depending on the directions ======
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The direction is defined by a number of an autonomous system that sends or receives the traffic. 
:!: The direction priority specified for autonomous system (if defined) overrides the priority specified by protocol.
:!: The direction priority specified for the traffic's source (if defined) overrides the priority specified for the destination.

<note important>One can change the IP list that belongs to an autonomous system and define an auxiliary autonomous system dynamically. It is described in the section [[dpi:dpi_options:opt_statistics:statistics_asn|Configuring autonomous systems]]</note>

The direction dependent priorities assigned by the system's administrator, are loaded by DPI from the file **/etc/dpi/asnum.dscp.**

<note warning>Comments in this file are not allowed!</note>

This file is created in two steps. First, the text file with a list of autonomous systems and their assigned priorities is created. Next, this file is converted into an internal format by a dedicated utility.

===== File format of autonomous systems' list and their priorities: =====

Each line of the file contains: AS_number <space> dscp_value. **For example:**
<code>
64512       cs0
64512       local
64513       drop
64514       pass
64514       peer
</code>
  * Here cs0 - is [[dpi:dpi_options:opt_priority:dscp_table|DSCP value]].\\ 

Keywords meaning:
  * drop – means that packets have not to be transmitted: they must be dropped.
  * pass – the traffic of this autonomous system must go through DPI with no analysis and processing.
  * local – the traffic of this system is treated as a local operator's one, see [[dpi:bras_bng:general_setup#fastdpi_l3_bras_setup|BRAS L3]]
  * peer – the operator is in peering state with this system; used only for [[dpi:dpi_options:opt_cache|Cache option]]
  * term – termination is allowed for this AS; see [[dpi:bras_bng:bras_l2_vlan_term:bras_l2_vlan_term_as|BRAS: AS termination]]
  * mark1 – Prioritize SNI detection in custom signatures for autonomous systems.\\ Control from the cloud. 
  * mark2 – QUIC traffic without SNI from this AS will be marked as QUIC_UNKNOWN_MARKED\\ Example:\\  
    * in asnum.dscp ASN 15169 mark as mark2 
    * in protocols.dscp mark QUIC_UNKNOWN_MARKED drop

<note important>local, term and peer do not effect the traffic's priority and are used for services. They are described there.</note>

===== File convertation =====

To convert this file into the internal format and to place it into the working directory for DPI usage:
<code>cat my_as_dscp.txt|as2dscp /etc/dpi/asnum.dscp
service fastdpi reload
</code>
<note important>This configuration is loaded on the run, with no need to restart the servic</note>
<note>**[SSG v13+]** it is now possible to add comments (#) and empty lines in input files of as2dscp utility.</note>

===== Configuration for local traffic =====
To allow the transit of local operator traffic through the DPI without analysing and processing:
<code>local_passthrough=1</code>

To place the local operator traffic in a separate class:
<code>local_dscp=0x38</code> 
dscp is set in a numerical form, the [[dpi:dpi_options:opt_priority:dscp_table|reference table]] provides correspondence between the numeric and letter symbols.\\ 

<note important>local_dscp setting takes precedence over the local_passthrough (if both are specified, the local_dscp is active)</note>

Autonomous system traffic within its class [[dpi:dpi_options:opt_bandwidth_mgmt:bandwidth_conf|can be limited]] regardless of the basic service plan limitation.