====== Assigning priorities according to the protocols ======
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The protocol priorities (assigned by system administrator) are loaded by DPI from the file **/etc/dpi/protocols.dscp.**

This file is created in two steps: first one creates a text file with the list of protocols and their priorities. Second, it is converted into an internal format by a special utility.

To apply the changes you need to the DPI configuration with the following command:
<code>service fastdpi reload</code>
===== The file format of protocols and priorities list: =====

Each line contains the protocol name, then space, then dscp value. **For example:**
<code>
dns         0x3F
skype       drop
compressnet 010
ftp         keep
http        cs0
default     keep
</code>
<note important>[[dpi:dpi_options:opt_statistics:statistics_info|Full list of protocols.]]\\
DSCP value is specified as [[dpi:dpi_options:opt_priority:dscp_table|decimal, hex or octal number or as a text abbreviation]].</note> 

Keywords meaning:
  * drop - indicates that packets must not be transmitted further. They must be dropped.
  * keep - shows that priority must keep its current value (typically 0).
  * default - means "for all remaining protocols" and allows to simplify significantly making the configuration file.

<note tip>To ensure that the ''drop'' action is applied only after TLS has been parsed and the SNI has been determined, you must add the parameter ''smartdrop = 1'' to ''fastdpi.conf''. This means that if ''drop'' is specified for a protocol, the action will be deferred until TLS has been parsed or a TLS parsing error occurs. This is a hot parameter; simply reload the configuration.</note>
===== Configuring Traffic Classification =====
1. Create a file named **protocols.txt** containing a list of the protocol groups we want to filter out from general traffic, along with their assigned priorities (classes):
<code>
dns cs0
ICMP cs0
http cs0
https cs0
QUIC cs1
default cs2
bittorrent cs7
</code>
where 
  * cs0 corresponds to priority 0, class 0, respectively 
  * cs1 corresponds to priority 1, class 1
  * cs7 corresponds to priority 7, the lowest class
<note important>This marking is taken into account in class-based policing rules.</note> 

2. Convert it to the DSCP format, which fastDPI understands
<code>
cat protocols.txt|lst2dscp /etc/dpi/protocols.dscp
</code>
<note>You can add comments (#) and blank lines to the input files of the lst2dscp utility.</note>

3. Apply the settings
<code>
service fastdpi reload
</code>


When moving settings to the working directory after saving a configuration backup, you must perform a reload after the move:
<code>mv protocols.dscp  /etc/dpi/protocols.dscp</code>
<note warning>Use only the mv command — it is atomic; do not use copying</note>