A Voice over IP Quality Monitoring Architecture

Transcription

1 A Voice over IP Quality Monitoring Architecture 8th International Conference on Management of Multimedia Networks and Services MMNS 2005 MANWEEK 2005 Barcelona, October 2005 Leandro Caetano Gonçalves Lustosa, Ms.C. Núcleo de Computação Eletrônica -NCE Universidade Federal do Rio de Janeiro - UFRJ

2 Service H.323 IP Phone (Software) Institution A H.323 Environment H.323 Environment Institution B H.323 IP Phone (Software) PABX VoIP Gateway Gatekeeper H.323 Gatekeeper H.323 H.323 IP Phone (Software) LDAP RADIUS SIP/H.323 Gateway SIP/H.323 Gateway RADIUS LDAP SIP IP Phone (Software) SIP Environment SIP Environment SIP IP Phone (Software) Proxy SIP Proxy SIP VoIP Gateway PABX SIP IP Phone (Software) Only Cisco gateways generates CDR with quality indicators Environment where the VoIP quality monitoring has been applied

3 VoIP Quality monitoring solutions Methodology Collection of gateways CDRs Simulated calls among distributed SNMP agents Passive monitoring Drawbacks Quality of calls between IP phones is not taking in account Real calls are not analyzed Statistics may not reflect the real network impact on voice calls Cryptography may block call analysis Point-to-point voice traffic may force packets to be routed away from the probes Examples CESNET and ECAS HUANG, CHAO e LIU BROOM e HOLLIER and several commercial solutions

4 Voice over IP quality monitoring architecture Methodology CDRs are collected directly from IP phones and voice gateways A new CDR format specification (Voice Quality CDR) Specific for voice quality monitoring Advantages More extensive and able to evaluate All real calls Cryptographic calls Point-to-point calls

5 Implementation Library for call quality evaluation and VQCDR generation (VQuality Library) IP phones and voice gateways incorporating VQuality Collection, authentication and storing of VQCDR Central entity (VQCDR Server) Storare database Authentication database

6 Voice Quality CDR (VQCDR) Call identifiers VoIP signaling protocol, codec, cally user, called user, etc Call Quality indicators Delay Impairment, Equipment Impairment, loss rate, jitter buffer discard rate, R-Factor, MOS, etc. Start time and call duration Optional fields Specific application information Voice Quality Log (VQLog) Quality history (call quality variation over time) Use of TCP/port 80 by default Reliable VQCDR transfer and facility for operation behind firewalls

7 Modified H.323 clients VQOpenPhone for Windows environments VQMeeting for Unix environments H.323 terminals based on OpenH323 library The RTT measurement mechanism of RTP/RTCP stack had to be implemented At the and of the call, clients evaluate the received voice quality, send the VQCDR and show the related MOS on their status panel

8 VQPlot Application that reads and plots VQLog files Together with a client that uses VQuality, like VQOpenPhone, it becomes a powerful analysis tool

9 VQuality CDR Server (VQCDR Server) Collector Module (CM): in charge of collecting and interpreting received VQCDR, and activation of AM and SM modules Authenticator Module (AM): in charge of VQCDR validation VQCDR Server Collector Module Authenticator Module Storage Module Storage Module (SM): in charge of storing received VQCDR in a database

10 GnuGK AM and RADIUS SM GnuGK AM Specific for Gatekeeper H.323 GnuGK Uses GnuGK remote port management for validating VQCDR originator RADIUS SM Specific for RADIUS However, RADIUS permits the interface with several SQL databases Use VSAs (Vendor Specific Attributes) to specify VQCDR fields (UFRJ 21715)

11 Visualization Environment All CDRs generated are sent to a RADIUS server and storied in a SQL server These CDRs are consolidated in one single record and statistical graphics and reports can be visualized on a Web interface

12 PQR * 4 7 S 1 2 A B C 4 5 G H I J K L 7 8 P Q R S T U V 3 D E F 6 M N O 9 W X Y Z * 0 # CISCO IP PHONE SERIES VoIP monitoring architecture summary VQCDR Server 3 The AM authenticates the VQCDR and activates the SM if it is valid GnuGK Authenticator Module (GnuGk AM) Authentication H.323 Gatekeeper GnuGK The AM access the GnuGK to validate the VQCDR 4 RadiusStorageModule (Radius SM) Radius Server 2 The CM collects the VQCDR and activates the AM ColectorModule(CM) VQCDR Generation 5 Storing If the VQCDR is valid, the SM access the Radius Server to store the VQCDR Storing The Radius Server receives the VQCDR and accesses the SQL Server to store the VQCDR information in a database 6 1 An IP Telephone integrated with VQuality evaluates the call quality and sends a VQCDR to the VQCDR Server IP Telephone with VQuality Web Server SQL Server 7 Call quality statistics are presented on a web based interface

13 Conclusions A new VoIP quality monitoring architecture was presented and implemented A new specific voice quality CDR (VQCDR) format was proposed A library for objective voice quality evaluation was presented (VQuality) Architecture validation Implementation of VQCDR Server Implementation of VoIP clients with VQCDR support VQOpenPhone (based on OpenPhone) VQMeeting (based on Netmeeting ) VQPlot VQLog file analysis It has been successfully applied in the RNP Brazilian research VoIP initiative

14 Future work Integration of VQuality into SIP clients and Asterisk Development of a specific AM for SIP SER Analysis of the database fed by the fone@rnp service Analysis of voice traffic in RNP network backbone Validation and improvement of QoS infrastructure Development of automatic call simulator and measurement tool Call capacity determination Study of QoS policies for voice traffic Use in wired and wireless environments Incorporation of VQuality to Network Simulator (NS2) Design and evaluation of complex VoIP systems