Control Systems & PLC's

Network Analyzer

What kind of Tap do I need for my network

Network TAPs provide a "Test Access Port" for analyzing high-speed networks in half or full duplex mode. When operating high-speed, high-capacity, data communications systems it is often necessary to monitor and analyze traffic with an absolute minimum disturbance to the data stream. Network taps provide inexpensive, permanent access ports throughout the network, enabling monitoring and analysis without interrupting transmission.

TAPs Advantages

TAP technology supports network monitoring and intrusion detection for almost any network configuration, including GigaBit SX, LX or ZX; ATM, DS3, T1 and Fast Ethernet copper. In addition, Net Optics just introduced the GigaBit TX to SX tap, the market's first copper-to-fiber tap. Network taps are extremely reliable, featuring passive-link integrity enabling the network to operate at a continuous flow.
These rack-mountable taps feature easy installation and broad compatibility: network managers can simply plug in the network cables to communicate with all major analyzer manufacturers' products including Network Generals' Sniffer®, Agilent's Internet Advisor & Cisco's SwitchProbe products, to name just a few.

 

TAPs Versus Span Port Connection

To enable monitoring and intrusion detection, most of the major switch vendors now support span (or mirror) ports on their switches. This allows the traffic to be sent to an analyzer port as well as the original designated port.

A Span Port solution has three major drawbacks.

1. First, it puts an increased load onto the switch that often increases CPU or memory requirements.
2. Second, when packets are sent to a span port, most vendors' switches remove low level (Layer 1, select Layer 2) errors from the stream of data. This makes low level troubleshooting impossible.
3. Third, if the link is a full duplex link running at full line rate, then to mirror this data would require a span port running at full line rate to get both directions of traffic. Unless a non-blocking switch is being used, large amounts of data could be lost because span port traffic is a low priority.

 

The tap solution for network monitoring and intrusion detection utilizes passive fiber or copper splitter taps on the main network links. This solution mitigates the trouble and expense associated with the three drawbacks mentioned above.

 

TAPs Versus In-Line Connection

Another common solution for monitoring and intrusion detection is to attach the analyzer in-line.
An in-line solution has two major drawbacks:

1. First, because it is not cost effective to leave an analyzer in-line, network managers must break a connection whenever they need to monitor.
2. Second, because the analyzer is not passive, attaching an analyzer in-line introduces a point of failure into the network.

The permanent, passive tap solution eliminates the risk and inefficiency associated with monitoring with an in-line analyzer connection.

Flexibility

Network taps provide network managers with the flexibility to monitor all aspects of the network 24/7. As network security and reliability continue to grow in importance, taps are an integral solution for any network.

Tap Types

Taps come in several varieties with different purposes and features. If you are confused about what type of Tap device you need in your network, here is a quick overview of the capabilities each type of Tap provides:

• Network Tap
• iTap
• Port Aggregation Tap
• Link Aggregation Tap
• Regeneration Tap
• Bypass Switch
• Converter

 

If you are using a hub or a Span port to get monitoring access to your network, you need a Tap!

About the Author

If you understand the Smithchart and bode plots, will is be easy for you to understand ...?

how network analyzers work

You have to understand Smith charts to be able to understand the information presented by the network analyzer. You will also need to understand "s" parameters for two or devices. Not difficult, once you get the concepts.

I found the larger challenge was to understand how to set up and calibrate the device to get accurate and repeatable measurements. It takes a lot of practice.

Some modern analyzers can do power measurements to measure DUT efficiency, time-domain measurements and mixer parameters.

CM2000: Multi-functional DOCSIS Network Analyzer