1. IRLP and EchoLink Integration Tony Langdon VK3JED For the IRLP Conference Las Vegas, USA April 16-17 2005

2. Contents ● IRLP and EchoLink – Differences. ● Guidelines for Interoperation. ● Early Dual System Nodes. ● EchoIRLP – The Integrated Dual Node. ● Linking Nets – The Analog Gateway. ● Problems With Analog Gateways. ● Digital Interconnections. ● Advantages and Constraints of Digital Links. ● The Integrated Conference. ● Practical Use of Cross Links. ● Looking to the Future. ● Questions.

3. IRLP and EchoLink - Differences ● IRLP is an RF only system. ● EchoLink permits direct PC access. ● IRLP uses PGP for authentication. ● IRLP nodes owners have to contact installation team to receive their PGP keys. ● EchoLink uses validation against online databases, with some applicants being hand validated. ● EchoLink uses encrypted password login. ● Technical differences have resulted in significant cultural differences.

4. Guidelines for Interoperation ● Cultural differences need to be taken into account when combining different networks. ● IRLP-EchoLink guidelelines documented in late 2002. ● Acceptable scenarios for combining IRLP and EchoLink. – Dual system node - EchoIRLP. – Linked IRLP/Echolink conferences. – Common conference server. – Emergency Communications – VoIP WX Net.

5. Early Dual System Nodes ● Many consist of two separate PCs and radios feeding the one repeater. ● More sophisticated systems use 2 PCs and 1 radio. ● These systems are prone to unintentional cross links. ● Many allow DTMF access to foreign network as a byproduct of their design. ● Audio quality is compromised, especially in systems using separate link radios.

6. EchoIRLP - The Integrated Dual Node ● Uses one machine and interface to allow connectivity to both systems. ● Lockouts between IRLP and EchoLink to prevent unintentional cross links. ● Uses tbd as a local gateway between IRLP controlling the hardware and the EchoLink network.

7. EchoIRLP Block Diagram

8. Linking Nets – Analog Gateways ● Consist of IRLP and Echolink nodes back to back.

9. Problems With Analog Gateways ● Multiple audio compression/decompression degrades audio quality. ● Excess latency caused by jitter buffers. ● Requires two extra PCs – cost and reliability issues. ● However, analog gateways have one advantage – they can be implemented at short notice without administrative intervention.

10. Digital Interconnections ● EchoLink conference capable of making an outbound Speak Freely connection.

11. Issues of Digital Links ● Audio is not decoded and recoded as it passes the gateway. ● Less audio degradation. ● Lower latency. ● Extremely difficult to tell whether originating station is on IRLP or EchoLink. ● IRLP stations must use GSM CODEC for digital link to work. ● Traffic passes directly between IRLP and EchoLink.

12. The Integrated Conference ● Modified IRLP reflector – Developed March-April 2005. ● Copy of sfreflect is replaced by tbd. ● One system – very reliable. ● All stations appear in EchoLink station list. IRLP nodes are labelled “stnXXXX”. ● Conference to be administered using both EchoLink and IRLP admin tools. ● Allows IRLP nodes to be muted – not normally supported.

14. Practical Uses of Cross Links ● Emergencies – VoIP Hurricane/SKYWARN Net. ● Regional coverage – New England Network. ● Special Events – 2003 9/11 Net.

15. Looking to the Future ● Digital interconnection for eQSO? – Dialogue opened with current maintainer of eQSOx. ● Establishment of an inter-system linking standard? – RTP based? – Standard would give all developers, including commercial ones something concrete to implement. ● Global Inter-Network Addressing? ● Co-operation between stakeholders allows rapid development. ● Limited only by imagination!

16. Acknowledgements ● Dave Cameron VE7LTD – IRLP System ● Jonothan Taylor K1RFD – EchoLink ● Skip Hansen WB6YMH – thebridge ● Pete Illmayer VK2YX – EchoIRLP update server ● Kent Johnson W7AOR – Test reflector ● EchoIRLP Developers – Open source has many contributors. ● And all those hams who offered positive feedback and made it all worthwhile.