Fast start and slow start are two different call setup procedures used in the H.323 protocol suite for real-time audio and video communication between endpoints. In this article, we will discuss the differences between a fast start and a slow start and their respective advantages and disadvantages.
Slow Start:
Slow start is the default call setup procedure in H.323. In this procedure, the call setup process involves a series of messages exchanged between the calling and called endpoints. These messages include the Setup, Call Proceeding, Alerting, and Connect messages. Each of these messages is exchanged separately between the endpoints before the call can be established. The slow start procedure provides the highest level of call control and allows each endpoint to negotiate the best possible call parameters before the call is established. However, this process can take a longer time to complete, leading to increased call setup time.
Fast Start:
Fast start is an alternative call setup procedure in H.323 that can be used to speed up the call setup process. In the fast start procedure, the call parameters are negotiated between the endpoints before the call setup process begins. This negotiation is done using a single message, known as the Fast Connect message. The fast start procedure allows for quicker call setup times than slow start, as the endpoints do not have to negotiate the call parameters separately. However, fast start provides less call control than slow start and may lead to suboptimal call quality if the negotiated parameters are not optimal.
Differences between Fast Start and Slow Start:
The main difference between fast start and slow start is the way call parameters are negotiated. In slow start, call parameters are negotiated through a series of messages exchanged between the endpoints, while in fast start, call parameters are negotiated through a single message. This difference results in varying levels of call control and call setup time. Slow start provides greater call control but takes longer to set up a call, while fast start provides less call control but faster call setup times.
Advantages and Disadvantages of Fast Start and Slow Start:
The advantages of slow start include greater call control and the ability to negotiate optimal call parameters, resulting in higher call quality. However, slow start also has the disadvantage of longer call setup times, which may be problematic in time-sensitive applications. The advantages of fast start include faster call setup times, which are beneficial in time-sensitive applications. However, fast start also has the disadvantage of less call control, which may result in suboptimal call quality.
In conclusion, fast start and slow start are two different call setup procedures used in the H.323 protocol suite for real-time audio and video communication between endpoints. The main difference between these procedures is the way call parameters are negotiated. Slow start provides greater call control but takes longer to set up a call, while fast start provides less call control but faster call setup times. The choice of which procedure to use depends on the specific needs of the application and the trade-off between call quality and call setup time.