OPTIMIZATION OF SIGNALING TRAFFIC IN CENTRALIZED CONFERENCES USING SIP Submitted by D.NEHRU S.JAYABALAN B.Tech IT II Year

INTRODUCTION Indispensable part of Multiparty Conferencing is Signaling Protocol by SIP. A Conference can be either Open or Closed. Two types of Conference Signaling used is Centralized Distributed Centralized Conference Signaling uses an Network element called CONFERENCE SERVER(CS). Conference Participants obtain a point to point Signaling connection with Conference Server.

Drawbacks of CS: Scalability Problems in Closed Conferences Conference Server represents a Single point of Failure.

SIP –Session Initiation Protocol SIP is an Application Layer Protocol developed by the Multiparty Multimedia Session Control (MMUSIC) working group of the IETF in The Purpose of SIP is Establishment Modification Termination of Sessions. SIP is independent of transport protocol. SIP provides reliability mechanism when an unreliable protocol (UDP) is used.

Types of messages in SIP Response Request SIP defines six types of Requests INVITE,ACK,BYE,CANCEL,OPTION and REGISTER. Two types of entity used are User Agents (UA) Network servers SIP ( Contd )

CENTRALIZED CONFERENCE SIP uses an network element for Centralized conference called CONFERENCE SERVER (CS). Two types of CS are Dial in Dial out Centralized Conference uses RTP and RTCP for distribution identities does not fulfill the requirements of closed conference. This Problem is solved by introducing new SIP method called CONF.

A BC D OK CONF OK CONF OK INVITE OK ACK JOINING A NEW PARTICIPANT IN A CONFERENCE

SIGNALING TRAFFIC OPTIMIZATION SIP extension could improved for Closed Centralized Conference in two points Improve scaling by reducing signaling traffic in CS. Use of Conference chair will avoid confusion in case of single point of failure. CS does not represent a single point of failure, because the conference chair would reinitialize the Conference when the CS crashes is possible because the conference chair knows the SIP address of each participant.

A BC D OK CONF INVITE OK ACK OK CONF JOINING NEW PARTICIPANT IN A CONFERENCE W ITH OPTIMIZATION CONF OK

CHANGING OF THE CONFERENCE CHAIR At the beginning of a Conferences,the conference chair is automatically the initiator of the conference. Changing the Conference chair is more useful, When the chair wants to leave the conference,it leaves without terminating the whole conference. If the previous chair does not specify the new chair,the CS will choose a new chair randomly between participants that were not the chair of this conference so far.

A BC OK CONF OK CONF BYE OK CONF OK CONF CHAIR CHANGING AND LEAVING THE CONFERENCE D 1 2

TERMINATING AND LEAVING THE CONFERENCE The conference chair able to terminate the whole conference at any time by sending a BYE request to the CS and respond to this, CS send BYE request to each participants and the conference is terminated. A Participant that is not the chair can leave the conference by sending a BYE request to the CS and participant will be removed from the conference. The Conference chair only wants to leave the Conference w ithout sending BYE message to the CS and the chair must first require the Change of chair.

RESULTS OF THE OPTIMIZATION We present results by two different scenario’s CONFERENCE INITIALIATION DOUBLE CHAIR CHANGE

CONFERENCE INITIALIZATION In the Scenario, comparison of traffic on the CS with or Without Proposed optimization without changing Conference chair is given. In the Scenario the traffic is growing quadratically with the number of participants without optimization and linearly with optimization.

SIGNALING TRAFFIC OF CONFERENCE INITIALIZATION SCENERIO Conference participants Messages Without optimization With optimization Without CONF

DOUBLE CHAIR CHANGE Without changing the chair the proposed optimization Obtains Excellentresults. From the below scenario we found that Optimized traffic is always lower than the traffic without Optimization. The difference between optimized and non optimized traffic is not as big as in the first case not only because of chair changes but also by the small number of Participants.

SIGNALING TRAFFIC OF DOUBLE CHAIR CHANGE SCENARIO Conference participants Messages Without optimization With optimization 4

CONCLUSION We Optimize the Signaling traffic on conference server by using the special participant called CONFERENCE CHAIR. The proposed optimization overcomes the problem of Scalability of closed conference Single point of failure in CS. The Traffic is growing quadratically with the number of Participants without optimization. The optimization proposed in the paper achieves a linear dependency between signaling traffic and number of Participants.

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