SIP EXPRESS ROUTER / KAMAILIO

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1 1 SIP EXPRESS ROUTER / KAMAILIO Nimal Ratnayake <nimalr@learn.ac.lk> CEO/CTO, Lanka Education and Research Network (LEARN) Senior Lecturer, Department of Electrical & Electronic Engineering, University of Peradeniya (on leave)

2 2 Which flavour Originally SIP EXPRESS ROUTER (SER) Project forked into OpenSER Forked again into OpenSIPS and Kamailio Kamailio and SER projects merged We will use Kamailio/SER Website:

3 3 Features Robust and Performant SIP (RFC3261) Server Registrar server Location server Proxy server SIP Application server Redirect server

4 Flexibility Written in C small footprint suitable for embedded devices the binary file is small size, functionality can be stripped/added via modules Modular architecture core, internal libraries and module interface to extend the server s functionality Extension repository overall more than 150 modules are included in the Kamailio source tree 4

5 5 SIP Routing Capabilities Stateless and transactional stateful SIP Proxy processing Serial and parallel forking NAT traversal support for SIP and RTP traffic Load balancing with many distribution algorithms and failover support Flexible least cost routing Routing failover Replication for High Availability (HA)

6 6 Transport Layer Supports UDP, TCP, TLS and SCTP IPv4 and IPv6 Transport layer gatewaying (IPv4 to IPv6, UDP to TLS, etc.) SCTP multi-homing and multi-streaming

7 7 Strengths / Limitations Very efficient proxy / registrar / location / redirect server Very efficient for call routing The core server is not designed to handle media (unlike Asterisk and its derivatives) PBX like features are missing Some modules provide media handling capabilities

8 Kamailio configuration One configuration file kamailio.conf Config file format Enabling modules and setting parameters for modules (e.g. MySQL module, LCR module, Authentication module,.) Basic networking options (IP address, Transport, port numbers, ) Debugging and logging settings etc Call routing logic most important part Documentation at 8

9 Kamailio configuration One configuration file kamailio.conf Config file format Enabling modules and setting parameters for modules (e.g. MySQL module, LCR module, Authentication module,.) Basic networking options (IP address, Transport, port numbers, ) Debugging and logging settings etc Call routing logic most important part Documentation at

10 Configuration file Core cookbook Pre-processor directives include_file path_to_filename #!define NAME #!ifdef NAME #!else #!endif

11 Core parameters advertised_address sets the visible name advertised_address="sip-router.org" alias sets aliases for your hostname If you wish to accept calls for otherdomain.org then you need to set alias= otherdomain.org children sets the number of child processes children=8 debug sets the debug level debug=3

12 Core parameters (2) enable_tls enables TLS transport enable_tls=yes listen sets the transport / IP address /port to listen in listen=tcp: :5060 listen=udp:[2004:dd00:3::199]:5060 listen= port sets the port number to listen in port=5066

13 Core parameters (3) loadmodule loads modules loadmodule "mysql" loadmodule "uri" loadmodule "lcr modparam sets module parameters modparam("usrloc", "db_mode", 2) modparam("usrloc", "nat_bflag", 6) log_stderror enables logging to stderror log_stderror=yes fork defines whether to run in server mode fork=no

14 Pseudovariables Special tokens that can be given as parameters to different script functions Begins with $ Set of predefined pseudo-variables Implemented by various modules, most of them are provided by pv Some are read-only, some are read-write List of pseudovariables at

15 Routing logic Controls the way kamailio handles various SIP requests and responses Main routing function is request_route (same as route) Within request_route various other specific route functions are called For a national sip router peering with the APAN SIP server and institution SIP servers, the most relevant function is route(relay)

16 route[relay] # CALL ROUTING FOR xxx (AARNET Call Manager - Bill E.) if (uri =~ "^sips?:\ [0-9]{3}@") { if ( isflagset(30) ) log ( 1, "DEBUG: Calls to Local Number Range 4xxx"); strip(1); $ru = $rz + ":" + $ru + "@ "; xlog ( "L_NOTICE", "DEBUG: After rewrite ruri=<$ru>\n"); }; # CALL ROUTING VIA APAN SIP SERVER if (uri =~ "^sips?:\+[1-9][0-9]{6,}@") { if ( isflagset(30) ) log ( 1, "DEBUG: Calls to APAN SIP Gateway"); $ru = $rz + ":" + $ru + "@ :5060"; xlog ( "L_NOTICE", "DEBUG: After rewrite ruri=<$ru>\n"); };