The IMS QoS Module

Dragos Vingarzan

   FhG Fokus
   <Dragos.Vingarzan@fokus.fraunhofer.de>

Jason Penton

   Smile Communications
   <jason.penton@smilecoms.com>

Richard Good

   Smile Communications
   <richard.good@smilecoms.com>

Carsten Bock

   ng-voice GmbH
   <carsten@ng-voice.com>

   Copyright © 2007 FhG FOKUS

   Copyright © 2012 Smile Communications

   Copyright © 2015 ng-voice GmbH
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. rx_dest_realm (string)
              3.2. rx_forced_peer (string)
              3.3. rx_auth_expiry (integer)
              3.4. cdp_event_latency (integer)
              3.5. cdp_event_threshold (integer)
              3.6. cdp_event_latency_log (integer)
              3.7. authorize_video_flow (integer)
              3.8. cdp_event_list_size_threshold (integer)
              3.9. audio_default_bandwidth (integer)
              3.10. video_default_bandwidth (integer)
              3.11. early_qosrelease_reason (String)
              3.12. confirmed_qosrelease_headers (String)

        4. Functions

              4.1. Rx_AAR_Register(route_block, domain)
              4.2. Rx_AAR(route_block, direction, subscription_id,
                      subscription_id_type)

        5. Statistics

              5.1. AAR Timeouts (aar_timeouts)
              5.2. Average AAR Response Time (aar_avg_response_time)

   List of Examples

   1.1. rx_dest_realm parameter usage
   1.2. rx_forced_peer parameter usage
   1.3. rx_auth_expiry parameter usage
   1.4. cdp_event_latency parameter usage
   1.5. cdp_event_threshold parameter usage
   1.6. cdp_event_latency_log parameter usage
   1.7. authorize_video_flow parameter usage
   1.8. cdp_event_list_size_threshold parameter usage
   1.9. audio_default_bandwidth parameter usage
   1.10. video_default_bandwidth parameter usage
   1.11. early_qosrelease_reason parameter usage
   1.12. confirmed_qosrelease_headers parameter usage
   1.13. Rx_AAR_Register
   1.14. Rx_AAR

Chapter 1. Admin Guide

   Table of Contents

   1. Overview
   2. Dependencies

        2.1. Kamailio Modules
        2.2. External Libraries or Applications

   3. Parameters

        3.1. rx_dest_realm (string)
        3.2. rx_forced_peer (string)
        3.3. rx_auth_expiry (integer)
        3.4. cdp_event_latency (integer)
        3.5. cdp_event_threshold (integer)
        3.6. cdp_event_latency_log (integer)
        3.7. authorize_video_flow (integer)
        3.8. cdp_event_list_size_threshold (integer)
        3.9. audio_default_bandwidth (integer)
        3.10. video_default_bandwidth (integer)
        3.11. early_qosrelease_reason (String)
        3.12. confirmed_qosrelease_headers (String)

   4. Functions

        4.1. Rx_AAR_Register(route_block, domain)
        4.2. Rx_AAR(route_block, direction, subscription_id,
                subscription_id_type)

   5. Statistics

        5.1. AAR Timeouts (aar_timeouts)
        5.2. Average AAR Response Time (aar_avg_response_time)

1. Overview

   This module contains all method related to the IMS policy and charging
   control functions performed by an Application Function (e.g. P-CSCF)
   over the Rx interface. This module is dependent on the CDP (C Diameter
   Peer) modules for communicating with PCRF as specified in 3GPP
   specification TS 29.214.

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The Following mouldes must be loaded before this module:
     * Dialog2
     * Usrloc PCSCF
     * TM - Transaction Manager
     * CDP - C Diameter Peer
     * CDP_AVP - CDP AVP Applications

2.2. External Libraries or Applications

   This modules requires the internal IMS library.

3. Parameters

   3.1. rx_dest_realm (string)
   3.2. rx_forced_peer (string)
   3.3. rx_auth_expiry (integer)
   3.4. cdp_event_latency (integer)
   3.5. cdp_event_threshold (integer)
   3.6. cdp_event_latency_log (integer)
   3.7. authorize_video_flow (integer)
   3.8. cdp_event_list_size_threshold (integer)
   3.9. audio_default_bandwidth (integer)
   3.10. video_default_bandwidth (integer)
   3.11. early_qosrelease_reason (String)
   3.12. confirmed_qosrelease_headers (String)

3.1. rx_dest_realm (string)

   This is the name of the Diameter realm of the Diameter server
   (typically a PCRF).

   Default value is 'ims.smilecoms.com'.

   Example 1.1. rx_dest_realm parameter usage
...
modparam("ims_qos", "rx_dest_realm", "ims.smilecoms.com")
...

3.2. rx_forced_peer (string)

   FQDN of the Diameter server (typically a PCRF) to communicate with. If
   not set then realm routing is used. If you use this, the routing
   defined in your diameter xml configuration file (CDP) will be ignored
   and as a result you will lose the benefits of load balancing and
   failover.

   Default value is ''.

   Example 1.2. rx_forced_peer parameter usage
...
modparam("ims_qos", "rx_forced_peer", "pcrf.ims.smilecoms.com")
...

3.3. rx_auth_expiry (integer)

   This is the expiry length in seconds of the initiated Diameter
   sessions.

   Default value is 7200.

   Example 1.3. rx_auth_expiry parameter usage
...
modparam("ims_qos", "rx_auth_expiry", 14400)
...

3.4. cdp_event_latency (integer)

   This is a flag to determine whether or slow CDP responses should be
   reported in the log file. 1 is enabled and 0 is disabled.

   Default value is 1.

   Example 1.4. cdp_event_latency parameter usage
...
modparam("ims_qos", "cdp_event_latency", 1)
...

3.5. cdp_event_threshold (integer)

   This time in milliseconds is the limit we should report a CDP response
   as slow. i.e. if a CDP response exceeds this limit it will be reported
   in the log file. This is only relevant is cdp_event_latency is enabled
   (set to 0).

   Default value is 500.

   Example 1.5. cdp_event_threshold parameter usage
...
modparam("ims_qos", "cdp_event_threshold", 500)
...

3.6. cdp_event_latency_log (integer)

   This time log level at which we should report slow CDP responses. 0 is
   ERROR, 1 is WARN, 2 is INFO and 3 is DEBUG. This is only relevant is
   cdp_event_latency is enabled (set to 0)

   Default value is 0.

   Example 1.6. cdp_event_latency_log parameter usage
...
modparam("ims_qos", "cdp_event_latency_log", 1)
...

3.7. authorize_video_flow (integer)

   This is a flag that specifies whether or not to authorize video flows.
   1 means video flows will be authorized over Rx and 0 means video flows
   will not be authorized over Rx

   Default value is 1.

   Example 1.7. authorize_video_flow parameter usage
...
modparam("ims_qos", "authorize_video_flow", 0)
...

3.8. cdp_event_list_size_threshold (integer)

   This is a threshold on the size of the cdp event list. Once the queue
   exceeds this length a warning is logged. 0 disables this feature

   Default value is 0.

   Example 1.8. cdp_event_list_size_threshold parameter usage
...
modparam("ims_qos", "cdp_event_list_size_threshold", 10)
...

3.9. audio_default_bandwidth (integer)

   This parameters defines the default bandwidth for Audio, if no
   "b=AS"-Parameter is found in the SDP.

   Default value is 64 (64 kBit)

   Example 1.9. audio_default_bandwidth parameter usage
...
modparam("ims_qos", "audio_default_bandwidth", 32)
...

3.10. video_default_bandwidth (integer)

   This parameters defines the default bandwidth for Video, if no
   "b=AS"-Parameter is found in the SDP.

   Default value is 128 (128 kBit)

   Example 1.10. video_default_bandwidth parameter usage
...
modparam("ims_qos", "video_default_bandwidth", 256)
...

3.11. early_qosrelease_reason (String)

   This sets the default Reason, when a call is terminated in early stage
   due to QoS-failure.

   Default value is "QoS released", an call in early stage would be
   released with "488 QoS released".

   Example 1.11. early_qosrelease_reason parameter usage
...
modparam("ims_qos", "early_qosrelease_reason", "Sorry - QoS failed")
...

3.12. confirmed_qosrelease_headers (String)

   These headers are added to the BYE-Message, when an confirmed call is
   terminated due to a QoS failure.

   Default value is "", no Extra-Headers

   The headers must end with CRLF.

   Example 1.12. confirmed_qosrelease_headers parameter usage
...
modparam("ims_qos", "confirmed_qosrelease_headers", "X-Reason: QoS failed\r\n")
...

4. Functions

   4.1. Rx_AAR_Register(route_block, domain)
   4.2. Rx_AAR(route_block, direction, subscription_id,
          subscription_id_type)

4.1. Rx_AAR_Register(route_block, domain)

   Perform a AAR on Diameter RX interface to subscribe to signalling
   status. This purpose of this is tell a Diameter server (typically a
   PCRF) to inform the requesting Diameter client on changes to the status
   of signalling bearer for the same framed IP address. For more details
   see 3GGP TS 29.214.

   Meaning of the parameters is as follows:
     * Route block to resume after async UAR Diameter reply.
     * domain that usrloc_pcscf uses to store user information.

   Return codes:
     * -1 - error: There was an error, so we must either ignore it (no
       subscription) or send 403 (depends on behaviour you want)
       0 - Success: AAR-Request sent, reply is processed asynchronously.
       1 - Success: No need to send AAR-Request, as a subscription still
       exists (continue as normal)

   This function can be used from REQUEST_ROUTE.

   p.s. this is executed asynchronously. See example on how to retrieve
   return value

   Example 1.13. Rx_AAR_Register
...
if(Rx_AAR_Register("REG_AAR_REPLY","location")==0){
    exit;
}
...
route[REG_AAR_REPLY]
{
    switch ($avp(s:aar_return_code)) {
        case 1:
            xlog("L_DBG", "Diameter: AAR success on subscription to signalling\n
");
            break;
        default:
            xlog("L_ERR", "Diameter: AAR failed on subscription to signalling\n"
);
            t_reply("403", "Can't register to QoS for signalling");
            exit;
    }
...

4.2. Rx_AAR(route_block, direction, subscription_id, subscription_id_type)

   Perform a AAR on Diameter RX interface to request resource
   authorisation from a Diameter server (typically a PCRF). For more
   details see 3GGP TS 29.214.

   Meaning of the parameters is as follows:
     * Route block to resume after async UAR Diameter reply.
     * direction of this message - orig, term, etc.
     * subscription_id to hard code subscription ID for AAR. Used for some
       broken PCRFs. Leave blank to use default
     * subscription_id_type to hard code subscription ID type for AAR.
       Only applicable if subscription_id is set. Set to -1 to use
       default. This is as per RFC 4006: END_USER_E164 0, END_USER_IMSI 1,
       END_USER_SIP_URI 2, END_USER_NAI 3, END_USER_PRIVATE 4

   This function can be used from REQUEST_ROUTE or ONREPLY_ROUTE.

   p.s. this is executed asynchronously. See example on how to retrieve
   return value

   Example 1.14. Rx_AAR
...
if(Rx_AAR("ORIG_SESSION_AAR_REPLY","orig","",-1)==0){
    exit;
}
...
route[ORIGN_SESSION_AAR_REPLY]
{
    if ($avp(s:aar_return_code) != 1) {
        xlog("L_ERR", "IMS: AAR failed Orig\n");
        dlg_terminate("all", "Sorry no QoS available");
    } else {
        xlog("L_DBG", "Diameter: Orig AAR success on media authorization\n");
    }
}
...

5. Statistics

   5.1. AAR Timeouts (aar_timeouts)
   5.2. Average AAR Response Time (aar_avg_response_time)

5.1. AAR Timeouts (aar_timeouts)

   The number of timeouts on sending a AAR. i.e. no response to AAR.

5.2. Average AAR Response Time (aar_avg_response_time)

   The average response time in milliseconds for AAR-AAA transaction.
