IP telephony in CESNET Sven Ubik

CESNET Association of universities and research institutes in Czech Republic Operates Czech NREN (CESNET2) 8 gigaPoPs

Goals and input create VoIP testbed reduce telephone charges provide new services accessible to as much people as possible various PBXs (Ericsson, Siemens, Alcatel, …) mostly Cisco routers ~ 10 major locations, ~10 minor locations

Design decisions Strategic: connecting PBXs, IP phones later standard PSTN numbering plan gateway to PSTN detailed accounting Technical: digital interfaces (ISBN PRI/BRI) Cisco voice gateways H.323 signalling no explicit QoS

VoIP network

Calling access prefix + standard PSTN number TU Prague  TU Ostrava TU Liberec  CERN, Switzerland

Measurement and accounting Using multiple accounting plans in parallel Several aggregation levels Listing of answered/unanswered/busy calls Open software Resilience to configuration changes Sven Ubik: „IP Telephony Accounting and WAN Deployment Experience“, IPTEL 2001, April 2001, Columbia University.

Linux MySQL LDAP authorization Measurement and accounting

PBX vs. IP phone Why PBX: PSTN phone on every desk simple and reliable easy authentication and accounting Why IP phone: no need for PBX new services „true“ convergence

H.323 vs. SIP Why H.323: widely supported mostly works Why SIP: simpler, textual, easier to debug easier programming of new services

What next, problems Connecting IP phones - authentication (LDAP ?) - numbering plan (organization-level prefix ?) - QoS in MANs, LANs IPTAv2 - graphical representation - PBX interface utilization - more information sources (GK, SIP server) International peerings - top-level GKs (one in Cesnet?) SIP clients - PBXs and SIP phones + SIP/H.323 GW