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IP Telephony Accounting and WAN Deployment Experience Sven Ubik [email protected] CESNET A not-for-profit organization for development and operation of Czech NREN • 2.5 Gb/s backbone (CESNET2 network) • Member of Géant and TERENA • Partner of Internet2 • Gigabit network testing laboratory Project goals • Interconnect PBXs of largest universities on CESNET2 network • Create VoIP testbed (e.g., for QoS for VoIP tests on a real WAN network) • Reduce cost of telephone calls between interconnected universities and to PSTN • Develop means for statistical measurement of VoIP traffic allowing optimization of PSTN / mobile phone gateway locations • Phase 2: QoS tests, IVR applications Pilot project Current VoIP network Current VoIP network • 16000 users • 11 voice gateways (Cisco) • 9 PBXs (Erricson, Siemens, Alcatel, Matra) • PSTN / mobile phone network gateway • Connection to CERN, Switzerland (Bremen and Hannover, Germany) • Mostly H.323 Statistical measurement - features • Flexible accounting plans and using multiple accounting plans in parallel • Output at different levels of aggregation • Modular architecture - using multiple protocols for gathering call data • Based on open software • Resilience against network configuration changes • Recovery from broken and lost call data Statistical measurement - design 3 layers: • Call data gathering (e.g., RADIUS, syslog) • Data processing • Presentation Where to account calls? Statistical measurement - architecture • Linux • MySQL database • LDAP authorization Call legs Using RADIUS messages Predefined set of attributes (RFC2865, RFC2866) does not contain some important information (e.g., start and end time of a session) 2 solutions: • Vendor-specific attributes • Overloading of AcctSessionId attribute Using RADIUS messages (cont.) Vendor-specific attributes h323-gw-id=AS2-OV.ten.cz h323-conf-id=4776D8CD B9A60177 0 37DBD1 74 h323-call-origin=answer h323-call-type=VoIP h323-connect-time=16:17:16.256 MET Mon Jan 22 2001 h323-disconnect-time=16:17:16.256 MET Mon Jan 22 2001 h323-disconnect-cause=10 h323-remote-address=195.113.134.240 Overloading AcctSessionId attribute 427/10:08:23.785 MET Thu Nov 23 2000/Voice-OV.ten.cz/ 9662886D A66029F 042FD97B4/answer/Telephony/ 10:08:54.544 MET Thu Nov 23 2000/10:08:57.194 MET Thu Nov 23 2000/10/195.113.134.240 Caching legs • Unneeded legs (may be needed later) • Broken legs (may be replaced by other legs) Statistical measurement - summary • Using multiple accounting plans in parallel • Recovery from broken and lost call data • Output at different levels of aggregation • Based on open software Specification of accounting parameters Example listing Contact information http://www.cesnet.cz/english/project/iptelephony [email protected] Online trial Register for username/password at: https://ipta.ten.cz/register Try at: https://ipta.ten.cz/test