4.4 Techniques for Control Signalling
The VoIPv6 application requires a method of control and signalling, there are numerous alternatives available in terms of methods of signalling such as SIP, H323, or a bespoke header which could be designed to be tailored to the exact needs of the application.
H323 is a very good protocol for IP telephony but it may be a little overkill for this application, it is very complex and uses gatekeepers to store who is on the network and help initiate calls between parties. H323 allows for calls between VoIP systems and traditional telephones in certain situations. With enough time for implementing H323 would be an ideal solution for this application; however all that is really required is for a way of allowing parties to initiate a call between two identical VoIPv6 systems.
SIP, Session Initiation Protocol is an IETF signalling protocol used to establish real-time calls and conferences over IP networks. SIP is a textual based internet protocol similar to HTTP and SMTP, this means problems can easily be diagnosed since SIP can be read easily by humans. SIP has mechanisms for call routing, call signalling and capabilities exchange, SIP is not too different to H323 except it promises scalability, flexibility and ease of implementations when building complex systems. However SIP is still a little complex and over-kill for what is required for this simple VoIP application.
A bespoke header could be designed which simple contained only the necessary commands for this VoIP application such as commands similar to Accept, to accept a call, Reject, to reject a call and so on and so forth. The advantages of using this method is that it more efficient than other methods since minimum information required for the application is sent keeping overheads to a minimum, this method would also give a header which is very easy to implement since straightforward parsing is all that is required.
For this application a bespoke header over TCP will be used, for the main reason it can be easily implemented since it is not very complex, it also has the added benefit of being small and efficient tailored to the applications needs. However and future work carried out on the project could look improving the signalling however this is discussed within the Further Work Section as the end of this report.
|
