IMS Usrloc PCSCF Module

Jason Penton

   Smile Communications

Edited by

Richard Good

   Smile Communications

   Copyright © 2012 Smile Communications
     __________________________________________________________________

   Table of Contents

   1. Admin Guide

        1. Overview
        2. Dependencies

              2.1. Kamailio Modules
              2.2. External Libraries or Applications

        3. Parameters

              3.1. hash_size (int)
              3.2. timer_interval (int)
              3.3. db_url (int)
              3.4. db_mode (int)
              3.5. hashing_type (int)
              3.6. lookup_check_received (int)
              3.7. match_contact_host_port (int)

        4. RPC Commands

              4.1. ulpcscf.status

        5. Statistics

              5.1. registered contacts
              5.2. impus
              5.3. expired contacts

   2. Frequently Asked Questions

   List of Examples

   1.1. Set hash_size parameter
   1.2. Set timer_interval parameter
   1.3. Set db_url parameter
   1.4. Set db_mode parameter
   1.5. Set hashing_type parameter
   1.6. Set lookup_check_received parameter
   1.7. Set match_contact_host_port parameter

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. hash_size (int)
        3.2. timer_interval (int)
        3.3. db_url (int)
        3.4. db_mode (int)
        3.5. hashing_type (int)
        3.6. lookup_check_received (int)
        3.7. match_contact_host_port (int)

   4. RPC Commands

        4.1. ulpcscf.status

   5. Statistics

        5.1. registered contacts
        5.2. impus
        5.3. expired contacts

1. Overview

   This module serves as a storage engine for PCSCF contacts, much like
   the standard Kamailio module, usrloc, is a storage engine for standard
   SIP contacts. The concept of a contact in IMS, PCSCF specifically, is
   very different to that of std. SIP and as a result we have built this
   new module. Alot of the design has been borrowed from the std. usrloc
   module. For example. An IMS contact, in PCSCF, needs things like:
     * Diameter Rx session for signalling bearer status. i.e. this is
       effectively QoS from the network to make sure the signalling link
       can be 'trusted'
     * IPSEC Security Assocation for secure signalling between UE and
       PCSCF (first point of contact)
     * IMPU, each contact can have a number of associated public
       identities (IMPU).

2. Dependencies

   2.1. Kamailio Modules
   2.2. External Libraries or Applications

2.1. Kamailio Modules

   The following modules must be loaded before this module:
     * None.

2.2. External Libraries or Applications

   The following libraries or applications must be installed before
   running Kamailio with this module loaded:
     * None.

3. Parameters

   3.1. hash_size (int)
   3.2. timer_interval (int)
   3.3. db_url (int)
   3.4. db_mode (int)
   3.5. hashing_type (int)
   3.6. lookup_check_received (int)
   3.7. match_contact_host_port (int)

3.1. hash_size (int)

   The number of entries of the hash table used by to store the contact
   records is 2^hash_size. For hash_size=4, the number of entries of the
   hash table is 16.

   Default value is 9.

   Example 1.1. Set hash_size parameter
...
modparam("ims_usrloc_pcscf", "hash_size", 10)
...

3.2. timer_interval (int)

   Number of seconds between two timer runs. The module uses timer to
   delete expired contacts.

   Default value is 60.

   Example 1.2. Set timer_interval parameter
...
modparam("ims_usrloc_pcscf", "timer_interval", 30)
...

3.3. db_url (int)

   Database URL

   Default value is "mysql://kamailio:kamailiorw@localhost/kamailio".

   Example 1.3. Set db_url parameter
...
modparam("ims_usrloc_pcscf", "db_url",
       "dbdriver://username:password@dbhost/dbname")
...

3.4. db_mode (int)

   This is the database mode to be used for the PCSCF usrloc data
   persistent storage. Currently this module supports the Write-Through
   scheme only.
     * 0 - This disables DB mode. Only memory will be used for usrloc and
       data will not survive a restart.
     * 1 - Write-Through Scheme. All changes to usrloc are immediately
       refelcted in the database. This is slow but very reliable. This
       mode will ensure that no registration data is lost as a result of a
       restart or crash.

   Default value is 0.

   Example 1.4. Set db_mode parameter
...
modparam("ims_usrloc_pcscf", "db_mode", 1)
...

3.5. hashing_type (int)

   This is used to specify how contacts are stored in the internal memory
   hashing structures. This is an important parameter, not only for
   efficiency, but also for functionality. IMS can get rather confusing
   when it comes to contacts, SIP URIs and Implicitly registered SIP URIs
   (IMPUs). Originally the hash for storage of contacts was performed over
   the full contact URI viz (27821234567@10.0.0.10:12345;user=phone). This
   scheme is useful (from a performance perspective) in circumstances
   where you have many SIP URIs being registered from the same host/port.
   However, this causes problems in IMS environments where an implicit
   registration set of IMPU's is implicitly registered on behalf of a UA
   when it registers. This is because the implicit contact being used in
   subsequent requests could use a different SIP URI, for example
   john.doe@10.0.0.10:12345. In this case the P-CSCF would not be able to
   retrieve the initial contact as the hash over the different contact
   would in most cases be different. It was therefore proposed to hash the
   contact by IP:PORT only, effectively identifying a "device" - assuming
   a 1-1 relationship between an IP:PORT pair. In our example, we would
   get to the same hash slot using the second SIP URI as we got using the
   initial registered SIP URI. Within this slot we can now search for the
   appropriate contact (remember there are still collision possibilities)
   and then traverse through the linked list if iumplcit IMPUs to find the
   contact currently being used. Of course if it is not found, then you
   can deny the request.
     * 0 - This uses the original hash over AOR method. By default we are
       backwards compatible...
     * 1 - Use the newer hash over the Host from Contact-Header.
     * 2 - Use the newer hash over the source-IP from where the request
       was received (useful for NAT-Scenarios)

   Default value is 0.

   Example 1.5. Set hashing_type parameter
...
modparam("ims_usrloc_pcscf", "hashing_type", 1)
...

3.6. lookup_check_received (int)

   If set to 1 (default), the Host in the contact will be checked against
   the Host, from which the request was received.
     * 0 - Upon lookup, do not check the host against received.
     * 1 - Compare the host in the contact against the received info.

   Default value is 1.

   Example 1.6. Set lookup_check_received parameter
...
modparam("ims_usrloc_pcscf", "lookup_check_received", 0)
...

3.7. match_contact_host_port (int)

   If set to 1 (default), the contact is matched using only host and port
   in the contact URI.
     * 0 - When matching contact do full contact match procedure.
     * 1 - When matching contact compare only host and port of the contact
       URI.

   Default value is 1.

   Example 1.7. Set match_contact_host_port parameter
...
modparam("ims_usrloc_pcscf", "match_contact_host_port", 0)
...

4. RPC Commands

   4.1. ulpcscf.status

   exported RPC commands.

4.1. ulpcscf.status

   Status of pcscf_usrloc, AORs, max slots, etc.

5. Statistics

   5.1. registered contacts
   5.2. impus
   5.3. expired contacts

   Exported statistics are listed in the next sections.

5.1. registered contacts

   Number of AOR contacts in registered state - cannot be reset.

5.2. impus

   Number of IMPUs - cannot be reset.

5.3. expired contacts

   Number of expired contacts - can be reset.

Chapter 2. Frequently Asked Questions

   2.1. Where can I find more about Kamailio?
   2.2. Where can I post a question about this module?
   2.3. How can I report a bug?

   2.1.

       Where can I find more about Kamailio?

       Take a look at http://www.kamailio.org/.

   2.2.

       Where can I post a question about this module?

       First at all check if your question was already answered on one of our
       mailing lists:
         * User Mailing List -
           http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-users
         * Developer Mailing List -
           http://lists.sip-router.org/cgi-bin/mailman/listinfo/sr-dev

       E-mails regarding any stable Kamailio release should be sent to
       <sr-users@lists.sip-router.org> and e-mails regarding development
       versions should be sent to <sr-dev@lists.sip-router.org>.

       If you want to keep the mail private, send it to
       <sr-users@lists.sip-router.org>.

   2.3.

       How can I report a bug?

       Please follow the guidelines provided at:
       https://github.com/kamailio/kamailio/issues.