Communication channels may encounter problems such as congestion due to heavy data traffic or bandwidth waste. To counter such problems, you can use different types of digital interface testers. Digital interface testers are third-party tools used for testing digital signals received by and transmitted from computers and other network devices such as modems, printers, and
The digital interface testers identify problems of the data transmission line, capture corrupted data, and detect common problems
Bit/Block Error Rate Testers (BERTs/BLERTs)
These digital interface–testing tools measure digital signals on peripheral devices such as PCs, printers, and Channel Service Unit/Digital Service Unit (CSU/DSU). They are also responsible for analyzing the data communication line, detecting corrupt data, and preventing corrupted data from reaching the destination node. In addition, these digital interface–testing tools monitor data that is transmitted from Data Terminal Equipment (DTE) through Data Communications Equipment (DCE). While monitoring the data transmission from a DTE through a DCE, these tools identify:
Corrupted bit patterns
Improper cabling within a network
Problematic situations such as traffic congestion during data transmission
For example, if you need to identify a problem in the connection between a CSU/DSU and a router, a breakout box can be deployed between the unit and the router. This helps determine whether the CSU/DSU sets the CTS high before the router transmits the data and sets the DTR high. This test enables you to determine if the router is appropriately transmitting data on the network.
However, the main
Network and protocol analyzers record, interpret, and analyze the operations of a protocol within a network. In addition, they filter traffic from a particular device and generate
When a node transmits frames on the network, the protocol analyzer captures the frames and decodes the protocol
The protocol analyzer also generates and transmits frames for capacity planning and for performing load tests on the network. For example, if network performance regularly deteriorates at a particular time or in a particular region, one of the possible reasons can be heavy network traffic during that period or in a particular region. To detect and reduce such performance-
A protocol analyzer works in two modes, capture and display. In the capture mode, it records the frames or the network traffic depending on certain performance criteria or a predefined threshold. For example, you may observe network downtime when data is transmitted to a particular network. To determine the exact cause of network failure, attach a threshold or filter to the protocol analyzer to capture the frames directed to that particular network. In such a situation, the protocol analyzer captures the frames directed to that particular network in the capture mode. The captured frames will have a timestamp attached to them that will determine the exact period during which the network performance deteriorates. This type of information is critical for organizations such as banks and stock exchanges that require seamless network connectivity.
In the display mode, a protocol analyzer decodes the captured frames and stores the information in a readable format for future interpretation. To view the captured frames, you can use thresholds. In addition, you can apply these thresholds to view only those frames that match a certain criteria.
Protocol analyzers are
Theoretical databases, which store information about the standards
Network-specific databases, which store information about the network topology
The expert system administrator uses this knowledgebase to generate a hypothesis that describes the most probable cause of the problem.
Based on the different characteristics and information captured, there are three types of protocol analyzers:
General purpose analyzers: Provide information about the network such as traffic monitoring, protocol capture, and network traffic modeling in the network design phase.
Provide information restricted to a particular network or LAN. The software is usually installed on a PC on the network and
High-end analyzers: Provide relatively expansive protocol decoding and capture traffic at higher rates. A significant feature of the high-end analyzer is the “generate and capture” capability, which is used for network capacity planning and load testing.
One of the most commonly used protocol analyzers is Sniffer Pro. It diagnoses network problems based on the symptoms. This product can decode as many as 250 protocols.
Another effective network protocol analyzer tool is Ethereal, which examines data in an active network and has a GUI for viewing data. You can interactively view both the summary and detailed information about the data packets. The tool assembles the data packets transmitted in a TCP session and displays the ASCII data for the session. In addition, it provides powerful filters, which accommodate a large number of fields.