QualNet Exercises: Chapter 4. Network Layer

Objective

The objectives of this exercise are to both help understand the Distance-Vector routing algorithm and learn how to implement a custom protocol in the QualNet simulator.

Overview

First, you will study and implement a simple Distance-Vector routing protocol, based on the provided protocol framework. Next, you will integrate the implemented routing protocol into QualNet. There is a tutorial on how to add a new custom routing protocol into QualNet which describes the entire process in a step-by-step manner.

Procedure

Part 1. A simple Distance-Vector (DV) routing protocol

In Part 1, you will implement a simple routing protocol based on the Distance-Vector algorithm. The protocol is named as Simple Routing Information Protocol (SRIP), which has two major functionalities:

Maintaining the routing table according to the DV alogorithm.
Forwarding data packets as they arrive by consulting the routing table.

Your job is to implement the SRIP algorithm. The necessary framework (including two files: routing_srip.h and routing_srip.cpp) is provided as a compressed tar file downloadable from here . The only file that you need to modify is routing_srip.cpp, where you will modify three out of four functions described below. Please go through both files as you read the following.

SripInit() -- This function is called upon starting the simulation initially. For SRIP, you should initialize the routing table in this function (i.e., set all distances to INFINITY and all next hops to INVALID_ADDRESS). Please do not forget to initialize the entry for the host node itself so that the distance is 0 and the next hop is its own address. Please examine the provided routing_srip.h and routing_srip.cpp code for details on the data structure of the routing table.
SripHandleProtocolEvent() -- This function is called whenever a "Route Update Broadcast" message (a.k.a., route update packet) needs to be sent to the neighbors. It is already provided and you do not need to make any change. This function responds to the "Route Broadcast Timer" message. When the timer expires, this function is called. The function constructs a "Route Update" packet, which includes all the valid entries of the routing table, and broadcasts it.
SripHandleProtocolPacket() -- This function is called whenever a protocol packet (which is a "Route Update" packet in SRIP) arrives. You need to modify this function to update the routing table according to the DV algorithm and the information received in the Route Update packet.
SripRouterFunction() -- This function is called whenever the IP layer receives a data packet from either its own transport layer or another node, and tries to determine the next hop to which the IP packet should be forwarded. The function consults the routing table to identify the entry for the destination of the received packet. If a valid next hop and distance value are found for the destination node, the packet is sent to the MAC layer using the function NetworkIpSendPacketToMacLayer().

Part 2. Adding a custom routing protocol into QualNet

In Part 1, you've learned to implement the major functions for SRIP. In Part 2, you will integrate the implemented protocol into QualNet.

Please download from here a compressed tar file, which includes the complete SRIP source, configuration files and a tutorial & README explaining in details the entire process of adding a routing protocol to QualNet. Integrate SRIP protocol into QualNet accordingly. Then re-compile and run QualNet with the provided SRIP configuration files srip.config and srip.app.

Questions

In which layer is SRIP implemented? How about Internet's RIP?
What five major functions are needed in order to implement a network layer routing protocol in QualNet?
List all types of protocol event(s)/timer(s) and packet(s) in SRIP?
Submit in the generated statistics file (srip.stat) after running QualNet with the provided SRIP configuration files (srip.config and srip.app), and answer the following:
- What is the SRIP "Route Update" interval used in above run?
- How many "Route Update" broadcasts are sent out at each node?

References and Further Readings

Sections 4.5 and 4.6 of the textbook.
Section 4.4.5 of the QualNet 5.0 Programmer's Guide.