Contents

Making new networks

The generation of a network file is very important because it contains the topology and timing parameters for the distributed system that is to be simulated. Also, it is useful to generate several newtork files for a protocol simulation, because with different network description files you can make different experiments and have a better idea of the protocol behavior.

By chosing Archives/NW Description-New from lydian.tcl, window GraphWin for LYDIAN will pop up. This drawing window is built on the GraphWin module of LEDA [2], which is a strong graph-constructing tool, so it is simple and intuitive for the user to generate network topology with nodes and edges by clicking mouse buttons. For detailed information how to use mouse to draw a graph in the GraphWin for LYDIAN window, press the Help button and choose Mouse.

Figure 17: New network generation interface

Then the user must select time distribution for the network in Timing button on the menu bar of the window.

• Asynchronous
• Uniform generates a random integer sample between Lower Limit and Upper Limit with equal probability.
• Geometric1 generates a random integer sample between Lower Limit and Upper Limit and according to a geometric distribution with mean value Mean.
• Geometric2 genarates a random integer sample between Lower Limit and Upper Limit and according to a geometric distribution with mean value Mean. The difference from geometric1 is that in geometric1 there is a cutoff of the values greater than Upper Limit (for these cases geometric1 returns Upper Limit) while geometric2 retries for finite number of tries and finally chooses a sample between Lower Limit and Upper Limit like as Uniform does.
• Normal generates a random integer sample between 1 and Upper Limit according to a Gaussian distribution with mean value Mean and variance Variance.
• Deterministic requires constant numbers from the user. The user is asked to define a step and a communication delay value for every node and every edge of the network.

 

 

Note: In LYDIAN, Lower Limit and Upper Limit must be in the range from $1$ to $100$ for all distributions

These randomizing functions are also available in LYDIAN library for the user to program new protocols. For more details, refer to Section 7.2.7
 
 

• Synchronous: this is intended to model systems where each process step takes the same or approximately the same time. This option is under development.
• ABD (Asynchronous Bounded Delay)
• Absolute synchronous

If the asynchronous mode is chosen, unique time distribution parameters are needed and are assigned to every node and edge of the distributed system.

After the time distribution selection the user needs to define whether spontaneous initialization of some or all nodes is required by chosing the Options button on the timing window (when the user choses one of time distributions, the respective timing window will pop up). This configuration belongs to the protocol the user uses. As an example, in protocol Broadcast with ACK, only one node in the network is allowed to be the initiator. The user can also give the time distribution parameters for the communication delays over these edges.
 

2002-11-11