1. Attribute Based Addressing for SIP Vlasios Tsiatsis †, Jyh-Cheng Chen ‡, Prathima Agrawal ‡ and Mani Srivastava† † UCLA Electrical Engineering Department, Los Angeles, CA, USA ‡ Applied Research, Telcordia Technologies, Inc. Morristown, NJ, USA April 2, 2001

2. Introduction • Network entities are named either by IP address or a fully qualified domain name • Users like descriptive and contextual names • e.g. “call my friend Bob”, “call the nearest policeman” • Call based and Packet based services in a natural way • e.g. “call my friends”, “send my friends this picture”

3. Contribution • Implement an additional user location service for SIP ... • .. as a distributed system of attribute based name resolvers SIP Server john@hol.gr INVITE helen@ucla.edu Query Location Server Reply helen@ee.ucla.edu INVITE helen@ee.ucla.edu ACK helen@ee.ucla.edu

4. Record No Distributed Name Resolution System • Database Records • User Description as a list of attribute value pairs • Database maintenance information • Maintenance Information • Attribute value pair list • a=1 • name = vlasios • occupation = student • city = Seattle

5. Requests/Responses • Each message is preceded by the requesting user identification • Registration (soft state) • Signoff • Description Modification • Query • Application Level Forwarding • Responses in XML form

6. B D A C Find all Friends Query Query Reply Friend Information/Request Processing • All requests are scoped • Currently update requests are replicated to all location servers • Queries like DNS

7. D Friends are at C B C A Send(Hello) to all Friends Friends are at A Friends are at B Registration Forwarding Application Level Forwarding What is we only wanted to push send messages to other users ? What is other users have variable attributes or they move ?

8. Integration with SIP • Used Columbia SIP client/server implementation • Added the necessary GUI for SIP client and the necessary code for SIP server • Used the extension mechanism of SIP (“Require” header) • Registration and Updates in REGISTER requests • Queries and Application Forwarding in INVITE requests

9. Future Work • Indexing Scheme for Information Processing and Distribution (currently replication) • What happens if a user wants to be found: • by specific users ? • by specific machines ? • at some specific time of the day ? • Push based messaging system

10. Conclusions • Provide a unified naming system for individuals or groups • Descriptive and natural naming system for IP telephony • Users concentrate on what they want • Suitable for packet oriented communication