It also opens up a host of potential security problems.Īnother method to monitor networks is to use port mirroring (called "SPAN", for Switched Port Analyzer, by vendors such as Cisco, and given other names, such MLXe telemetry by Brocade Communications and other vendors)(also known as MIRROR port) or a monitoring protocol such as TZSP on routers and switches. Many vendors have alleviated this by using intelligent polling schedulers, but this may still affect the performance of the device being monitored. The inherent problems with SNMP are the polling effect. This scales well, but is not necessarily appropriate for all types of monitoring. It can also impact the network being monitored see observer effect.Īnother way to monitor devices is to use a remote management protocol such as SNMP to ask devices about their performance. However, it does not scale well to large networks.
This is the cheapest way to monitor a network, and is highly appropriate for small networks. The simplest type of monitoring is logging into an interesting device and running programs or commands that show performance statistics and other data. This type of tapping is often the cheapest one to implement, but it needs several implementations to give a truly complete look of the network. This type of tapping focuses on tapping by making use of software, and without making any significant change on an infrastructures hardware. Many tapping methods can be used, according to the network technology, the monitoring objective, the resources available and the size of the target network. There are various methods for monitoring a network. All of the "vendor terms" are common within the industry, have real definitions and are valuable points of consideration when buying a tap device.Ī distributed tap is a set of network taps that report to a centralized monitoring system or packet analyzer. Before buying any product it is important to understand the available features, and check with vendors or read the product literature closely to figure out how marketing terms correspond to reality. Vendors will tend to use terms in their marketing such as breakout, passive, aggregating, regeneration, bypass, active, inline power, and others Unfortunately, vendors do not use such terms consistently. The packets must be aligned into a single stream using a time-of-arrival algorithm.
There may also be an aggregation port for full-duplex traffic, wherein the A traffic is aggregated with the B traffic, resulting in one stream of data for monitoring the full-duplex communication. The monitored traffic is sometimes referred to as the pass-through traffic, while the ports that are used for monitoring are the monitor ports. Some vendors define TAP as an acronym for test access point or terminal access point however, those are backronyms. The term network tap is analogous to phone tap or vampire tap. Taps are used in security applications because they are non-obtrusive, are not detectable on the network (having no physical or logical address), can deal with full-duplex and non-shared networks, and will usually pass through or bypass traffic even if the tap stops working or loses power.
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Network taps are commonly used for network intrusion detection systems, VoIP recording, network probes, RMON probes, packet sniffers, and other monitoring and collection devices and software that require access to a network segment. A tap inserted between A and B passes all traffic (send and receive data streams) through unimpeded in real time, but also copies that same data to its monitor port, enabling a third party to listen. The network tap has (at least) three ports: an A port, a B port, and a monitor port. A tap is typically a dedicated hardware device, which provides a way to access the data flowing across a computer network. JSTOR ( May 2018) ( Learn how and when to remove this template message)Ī network tap is a system that monitors events on a local network.Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources.
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