9.5 Test Tools and Equipment

Testing the communications software on the target involves various types of test tools and equipment. For example, protocol conformance testing for the IP suite can be done with a tool like Automated Network Validation Library (ANVL) from Ixia Corporation. The test generates packets for specific protocols on an interface connected to the router, while the other interface is used to observe behavior (see Figure 9.4). For example, to verify correct forwarding, the tool can generate a packet on Port 1, with a destination address equal to the IP address of Port 2 in Figure 9.4. The system under test (SUT) will forward the packet on its Port B to Port 2 of the test tool. The tool receives the packet, verifies it, and updates the test result information.

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Figure 9.4: ANVL test tool.

While ANVL is a conformance tool offering some level of performance-based testing, there are specific types of test equipment such as those from Agilent, NetTest, and Spirent which incorporate conformance as part of a test suite portfolio. These types of test equipment perform two basic functions:

Analysis

the test equipment captures the frames and then decodes and analyzes the data for correctness.

Simulation

the test equipment generates packets for specific protocols and verifies the responses.

Simulation often involves a light-weight implementation of the protocol with its state machines, packet generation and reception, and a limited amount of configuration.

The test equipment can also be used to validate performance such as the forwarding rate, latency, jitter, and so on. This is usually done on the complete system with the hardware and software subsystems integrated.

The Importance of Testing

Testing is a very important part of the product development life cycle. Communications equipment needs to be tested with other types of equipment in complex network topologies, since customers may deploy the equipment in large networks. Several equipment vendors build large labs for testing their equipment, in some cases doing a mini-replica of customer topologies. In addition, there are several test laboratories like the University of New Hampshire, George Mason University, EANTC, who offer testing services. Equipment and software vendors can take their products to these facilities to get them tested and certified.

Due to the complexity and interaction of multiple protocols as well as the high data rates, it is important that testing be carried out in a structured manner at all stages— unit, integration, and system testing. Like other areas of embedded systems, inadequate testing of communications software can come back to haunt the developers. A problem in the field is much more difficult to fix than one in the lab.



Designing Embedded Communications Software
Designing Embedded Communications Software
ISBN: 157820125X
EAN: 2147483647
Year: 2003
Pages: 126
Authors: T. Sridhar

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