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Activities of LEARN:Introduction of VoIP services using

Open Source Software

Nimal Ratnayake<nimalr@learn.ac.lk>

Technical Manager, Lanka Educational and Research Network (LEARN)

Senior Lecturer, Department of Electrical & Electronic Engineering, University of Peradeniya

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Introduction

• LEARN: Lanka Educational and Research Network

• Interconnecting academic/research institutions within Sri Lanka

• Established in 1990

• Currently interconnects– 11 universities (some with multiple campuses)– National Science Foundation– University Grants Commission

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LEARN Services

• Internet Services– Two links to local ISPs– Bandwidth management using squid proxy– Some universities have their own links to ISPs

• Electronic Mail Services– Incoming/outgoing mail relay for universities– Virus/Spam filtering using

AmaViS/SpamAssassin– Virtual hosting and POP/IMAP based mail

services for individuals/organizations

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LEARN Services (2)

• Training programs/Workshops– For technical staff conducted by local resource

persons– For technical staff conducted by foreign

resource persons with funding from Sida– International events such as NetSA

• Consulting– Networking

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Developments

• Currently under the UGC– LEARN is a non existent entity: delays in

universities paying their bills

• Reorganization (under discussion)– Non profit organization– Membership levels: Full member, Affiliate– Minimum core staff: 3 Engineering, 2 other– Annual membership fee + Internet access costs– Organizational structure: Management

committee, Technical committee

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New applications

• Many universities still see LEARN only as an ISP– Utilization of the network for inter university

educational/research activities is very low

• New applications– Remote teaching/learning– Voice over IP– Video conferencing– Multicasting of special events

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Voice over IP

• Roadmap– Use for communication among network

engineers at member institutions and Technical Manager

– SIP proxy/registrar servers at each university – Introduction of the services within and between

campuses– Gateways to campus PBXs and PSTN

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Software used

• Sip Express Router (SER)– Version 0.8.11 running on a Linux box (RedHat

8.0 with kernel 2.4.18)– Written in C, modular– We use proxy and registrar/location server– Also use MySQL module for interacting with

user database– HTTP Authentication

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User agents

• Used several user agents– Kphone (Version 3.11 running on Linux)– Ubiquity/Helmsman (Version 3.0.9 running on

windows)– MSN Messenger– SipC

• Interoperability of UAs satisfactory

• Noticeable echo in some situations

• Latency variations during session

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Authentication

• HTTP digest authentication (RFC 2617)– Authenticator needs to know the cleartext

password– Implications: Unix passwords, LDAP etc cannot

be used– Currently we keep the cleartext password in

MySQL database– Alternative authentication schemes is a

research topic

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Gateways

• SipRG: SIP Residential Gateway– Written in C++, somewhat bulky– Supports QuickNet telephone interface cards

• Open H.323 gateway– Supports the Voicetronix cards– SIP/H.323 translation required

• Cisco proprietary solutions– Currently the most widely used option– Requires some of our routers to be upgraded