{{tag>Services "Service 18" "Per-Session Policing"}}

====== Policing by session and overriding traffic classes ======

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<note>[[dpi:dpi_components:dpiui:user_guide:ssg_control_section:services:session_policing|Configuring Session Policing via GUI]]</note>

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Policing by session and traffic class override is implemented using connection 18 services for Subscriber and Virtual Channel (vChannel). 

The service extends the possibilities of policing by determining the traffic rate for a particular session. It is also possible to override the traffic class for a specific Subscriber or Virtual Channel. 

Recall that global traffic class markup is described in [[dpi:dpi_options:opt_priority|]]. \\

Important: Directional priority overrides protocol priority, so if traffic already has [[dpi:dpi_options:opt_priority:priority_config_as|]], this service will not override the traffic class. 

===== SSG Configuration =====

The service **requires additional RAM** (compared to standard requirements), which is reserved by a setting in **/etc/dpi/fastdpi.conf**:

<code bash>support_service_18=1 </code> 

To apply the settings, you must restart the service: **service fastdpi restart**

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<note important>**SSG 12.4+** For vchannel DSCP is defined **only** if the ''support_service_18'' parameter is set!</note>

===== Setting up and managing the service =====

==== Configuring Policing by Session ====

It is necessary to create a file describing the speed for a particular protocol and convert it using the lst2tbf utility.

  * rate - session polysing rate for outgoing traffic

  * inbound.rate - polysing rate by session for incoming traffic

  * burst - short-term excess rate

  * inbound.burst - short-term excess inbound.rate

<code bash>

speedtest tbf rate 16mbit inbound.rate 16mbit

bittorrent tbf rate 8Mbit

TCP Unknown tbf rate 8Mbit burst 1Mbit inbound.rate 8Mbit inbound.burst 1Mbit

cat tbf_prof_1.txt|lst2tbf /tmp/tbf_prof_1.tbf