QOS Module

Ovidiu Sas

SOMA Networks, Inc.

Edited by

Ovidiu Sas

Table of Contents

1. Admin Guide
1. Overview
2. How it works
3. Dependencies
3.1. Kamailio Modules
3.2. External Libraries or Applications
4. Parameters
4.1. qos_flag (integer)
5. Functions
6. Statistics
7. Exported pseudo-variables
8. Installation and Running
2. Developer Guide
1. Available Functions
1.1. register_qoscb (qos, type, cb, param)

List of Examples

1.1. Set qos_flag parameter

Chapter 1. Admin Guide

1. Overview

The qos module provides a way to keep track of per dialog SDP session(s).

2. How it works

The qos module uses the dialog module to be notified of any new or updated dialogs. It will then look for and extract the SDP session (if present) from SIP requests and replies and keep track of it for the entire life of a dialog.

All of this happens with a properly configured dialog and qos module and setting the dialog flag and the qos flag at the time any INVITE SIP message is seen. There is no config script function call required to set the SDP session tracking mechanism. See the dialog module users guide for more information.

A dialog can have one or more SDP sessions active in one of the following states:

  • pending - only one endpoint of the SDP session is known.

  • negotiated - both endpoints of the SDP session are known.

An SDP session can be established in one of the following scenarios:

  • INVITE/200ok - typical "INVITE" and "200 OK" SDP exchange.

  • 200ok/ACK - "200 OK" and "ACK" SDP exchange (for calls starting with an empty INVITE).

  • 183/PRACK - early media via "183 Session Progress" and "PRACK" (see RFC 3959 for more information) - not implemented yet.

3. Dependencies

3.1. Kamailio Modules

The following modules must be loaded before this module:

  • dialog - dialog module and its dependencies (tm).

3.2. External Libraries or Applications

The following libraries or applications must be installed before running Kamailio with this module loaded:

  • None.

4. Parameters

4.1. qos_flag (integer)

The module will not do anything to any message unless instructed to do so via the config script. You must set the qos_flag value in the setflag() call of the INVITE you want the qos module to process. But before you can do that, you need to tell the qos module which flag value you are assigning to qos.

In most cases when ever you set the dialog flag you will want to set the qos flag. If the dialog flag is not set and the qos flag is set, it will not have any effect.

This parameter must be set or the module will not load.

Default value is Not set!.

Example 1.1. Set qos_flag parameter

modparam("dialog", "dlg_flag", 5)
modparam("qos", "qos_flag", 7)
route {
  if (method=="INVITE") {
    setflag(5); # set the dialog flag
    setflag(7); # Set the qos flag

5. Functions

There are no exported functions that could be used in scripts.

6. Statistics

There are no exported statistics for the qos module.

7. Exported pseudo-variables

There are no exported pseudo-variables for the qos module.

8. Installation and Running

Just load the module and remember to set the flag.

Chapter 2. Developer Guide

1. Available Functions

1.1.  register_qoscb (qos, type, cb, param)

Register a new callback to the qos.

Meaning of the parameters is as follows:

  • struct qos_ctx_st* qos - qos to register callback to. If maybe NULL only for QOSCB_CREATED callback type, which is not a per qos type.

  • int type - types of callbacks; more types may be register for the same callback function; only QOSCB_CREATED must be register alone. Possible types:

    • QOSCB_CREATED - called when a new qos context is created - it's a global type (not associated to any qos).

    • QOSCB_ADD_SDP - called when a new SDP was added to the qos context - it's a per qos type.

    • QOSCB_UPDATE_SDP - called when an existing SDP is updated - it's a per qos type.

    • QOSCB_REMOVE_SDP - called when an existing SDP is removed - it's a per qos type.

    • QOSCB_TERMINATED - called when the qos is terminated.

  • qos_cb cb - callback function to be called. Prototype is: void (qos_cb) (struct qos_ctx_st *qos, int type, struct qos_cb_params *params);

  • void *param - parameter to be passed to the callback function.