SIP.edu Speaker: Changyu Wu Adviser: Quincy Wu Date:2006/12/18

2 Overview Introduction SIP.edu implementation Architecture Call flow PSTN Voic Campus extension Goals Conclusion Reference

3 Introduction Build a community of Internet2 schools that is experimenting with offering enterprise SIP services. The initial SIP.edu architecture works by integrating the legacy campus PBX and person directory with two new components A SIP proxy server A SIP PBX gateway.

4 Introduction-(cont) Users should not be burdened with device addresses. Addresses should be empower enterprises to manage the identities of their users For instance Alice to call Bob using Bob's address (e.g.

5 SIP.edu implementation A SIP DNS SRV record pointing to a SIP proxy server. A SIP proxy server integrated with the campus directory to alias internal extension numbers to usernames. A SIP-PRI (Primary Rate Interface ) gateway to terminate inbound SIP calls and gateway to the correct “black phone” through the campus PBX.

6 SIP.edu implementation-DNS SRV The domain name system (DNS) stores and associates many types of information with domain names Translates domain names (computer hostnames) to IP addresses. The SRV resource record allows administrators to use several servers for a single domain.

7 DNS-SRV Example: Want to make a SIP phone call to the SRV record might tell your computer that it should connect to

8 SRV record (RFC2782) Type: _Service._Proto.Name TTL Class SRV Priority Weight Port Target _sip._utp.ncnu.edu IN SRV sip.ncnu.edu The service is SIP. The transport is UDP. The cache lifetime is 12 hours (43,200 secondes.) The class is IN (this is always true.) The record type is SRV.

9 SRV record (cont) The priority is 10. With multiple SRV records the priority determines the proxy query order. The weight is 10. With multiple SRV records of similar priority, the weight determines proportionally how often a proxy is queried. Higher values are queried more often. The port is The proxy server is sip.ncnu.edu sip.ncnu.edu sip.ncnu1.edu sip.ncnu.edu sip.ncnu1.edu sip.ncnu2.edu _sip._utp.ncnu.edu IN SRV sip.ncnu.edu

10 SIP.edu implementation- SIP proxy server SER (SIP Express Router) is an open-source SIP proxy. Configurations Ser.cfg. Use Mysql(Database) support user’s directory (username, phone number, ..). Ser tables (subscriber).

11 SIP.edu implementation-SIP Gateway SIP Gateway Connects to existing PBX or Centrex Could also connect to proprietary VoIP system

12 SIP.edu Architecture Alice DNS SRV query _sip._udp.ncnu.edu INVITE INVITE Telephone number where mail=bob PRI/CAS Bob’ phone Ncnu.edu

13 SIP.edu Call flow (PSTN ) Internet Ncnu net SIP server Ncnu PBXPSTN Call :09XXXXXXXX SIP/PRI Gateway Alice Bob’ phone

14 Ser.cfg (PSTN) If { rewritehostport(“ :5060”); forward(uri:host, uri:port); break; } rewritehostport(“string”) =>rewrite host part of Request URI forward(“”) =>forward the request to given destination statelessly

15 SIP.edu Call flow (Voic ) Internet Ncnu net SIP server Ncnu PBXPSTN SMTP server SMTP mail SIP/PRI Gateway Alice Bob’ phone Alice call john John not on line John

16 Ser.cfg (Voic ) AVPops modules Implementing services and preferences per user or domain. The AVPops module exports functions for interfacing DB resources. Exported Parameters. Exported Functions.

17 Ser.cfg (Voic ) Avp configuration setting module-specific parameters modparam("avpops", "avp_url", modparam("avpops", "avp_aliases", " =i:67") modparam("avpops", "avp_aliases", "mode=i:343") modparam("avpops", "avp_table", "subscriber") modparam("avpops", "uuid_column", "uuid") modparam("avpops", "db_scheme", _scheme:table=subscriber;value_col= _address;value_type =string") modparam("avpops", "db_scheme", mode_scheme:table=subscriber;value_col=show_mode;value_type =string") modparam("tm", "tw_append", "voic _headers:hdr[User_Agent];P- -Address=avp[$ ]")

18 Ser.cfg (Voic ) Avp configuration request routing logic if (avp_db_load("$ruri", “$mode/$mode_scheme")) { avp_write("2", "s:voic "); avp_db_load("$ruri","$ /$ _scheme"); if (avp_check("voic ","eq/$mode/g")) { if(!t_newtran()) { break; }; t_write_req("/tmp/am_fifo", "voic /voic _headers"); break; }; } => 2.mode_scheme => 2 3.mode=mode_scheme 4.mode=2 $mode=2 Voic =2

19 SIP.edu Call flow (Campus extension ) Internet Ncnu net SIP server Ncnu PBXPSTN DNS SRV SIP RTP SIP/PRI Gateway Alice Bob’ phone

20 Goals The goals of the working group are to: Grow number of SIP connected users. Increase value proposition for end-user SIP adoption. Promote convergence of voice and identity. Low entry-cost means for campuses.

21 Conclusion How is “SIP.edu” Implementation DNS SRV SIP proxy server SIP Gateway Architecture and Call flow How to use “SIP.edu” services? Design a Interface PHP+Mysql The user selects services.

22 Reference SIP.edu DNS SRV (RFC2782) AVpops SEMS SER The Internet2 SIP.edu Initiative (June 2, 2003) Dennis Baron Jeremy George Ben Teitelbaum