Support of Multimedia SIP Applications over Proactive MANETs Extension of OLSR for Service Discovery

Transcription

1 Support of Multimedia SIP Applications over Proactive MANETs Extension of OLSR for Service Discovery Li Li and Louise Lamont CRC Canada

2 Outline Overview of MANET Service Discovery Schemes OLSR Extension to Support Service Discovery SIP MANET Networking Architecture Performance Results Conclusions

3 Service Discovery To find the IP-address of a service provider by specifying the desired service properties, which can then be contacted by the client for the service session. The key service properties: service type, service URL/AOR, attributes, preference of attributes, etc. Service discovery schemes developed for the fixed networks often employ the centralized servers which may not exist in the MANET, e.g., DNS, DHCP, ENUM etc.

4 Overview of MANET Service Discovery Schemes Host-name-to-address mapping Adapt DNS protocol to MANET (draft-jeong-manet-dns-service- 00.txt) Piggyback onto reactive routing protocol (draft-engelstad-manetname-resolution-01.txt) SLP adapted to MANET Piggyback onto reactive routing protocol (draft-koodli-manetservice-discovery-00.txt) Building distributed service directory layer in MANET (U Kozat and L Tassiulas ) Service advertising and discovery on Multicast Protocols Often reactive multicast routing protocols are assumed (e.g., Liang Cheng)

5 Service Discovery in Proactive MANET Proactive MANET is more suitable for certain application scenarios, e.g., for support of real-time multimedia SIP applications with minimum end-toend latency Apply cross-layer design between networking and application layers to reduce the infrastructure and protocol overhead Service advertisement may fit well in OLSR s forwarding mechanism Can service query-and-response messages be supported by OLSR forwarding mechanism?

6 Extension on OLSR to Support Service Discovery A new message type to handle the functionality of service discovery: Service Location Extension (SLE) MANET Server OLSR forwarding to disseminate the SLE message forwarding to advertise the service capability Service query-and-response using forwarding Response SLE is the same as the advertising SLE SLE refresh timer, SLE minimum refresh timer and limited maximum number of queries to control message load Backward compatibility with OLSR nodes that do not support the SLE extension

7 SLE Message Major fields include: Service Sequence Number, Service Type, Service Attributes, AOR URL, Location, Weight, Query Flag, etc. Service Attributes are service type dependent, including attribute values and preferences The AOR URL can be omitted when the Query Flag is enabled Location field stipulates IP address

8 SIP MANET Networking Architecture Two types of servers, proxy server and UAS are involved MANET 3 2 MN_Proxy MN_Proxy2 MANET : register 2: send INVITE request 3. route the INVITE request to the called (a) Proxy-based SIP MANET 1: send INVITE request directly to the called (b) Proxy-less SIP MANET Proxy-based vs. Proxy-less SIP MANET Architecture Proxy server offers SIP directory service Need to discovery either the proxy server(s) or all destination UAS

9 Support SIP MANET Over OLSR Use OLSR SLE to automatically discover the SIP MANET architecture and locate the server(s) Listen for server advertisement Query message first solicits the proxy server to respond. A UAS only responds when there is no proxy server heard in the SIP MANET To further reduce the message overhead, uni-cast response may be used

10 Performance Evaluations - Comparison of OLSR SD scheme with SD scheme piggybacked on the reactive routing protocol 1 1 MANET Server MANET Server Assume two broadcast queries generating more message load than a forwarded query-and-response pair OLSR SLE scheme can outperform the reactive SD scheme in many cases

11 Simulation Results SLE Message Overhead Call Setup Time: proxyless netw ork Percentage of SLE in total OLSR traffic 0.80% 0.60% 0.40% 0.20% 0.00% proxy-less Scenarios one proxy server big net small net setup time (sec) sec Case1 Case2 simulation tim e (sec) SLE overhead is insignificant in proportion to the overall OLSR overhead Satisfactory performance results of SIP applications are achieved with the proposed service discovery scheme

12 Conclusions Cross-layer support of service discovery utilizing the OLSR protocol achieves implementation, architecture and protocol efficiency The extra message overhead generated by SLE is very limited OLSR SLE scheme may outperform reactive SD schemes in many cases The proposed OLSR SD scheme delivers satisfactory performance metrics for support of multimedia real-time applications

13 Thank You!