A network test access point, or shortly network TAP, is a hardware device meant to passively capture traffic on a network and usually used to monitor the network traffic between two points of the network.
The most common definition used for a network test access point (TAP) is that it is a hardware tool that which allows access and monitor of a network by transmitting both the send and receive data streams simultaneously on separate dedicated channels without compromising the connection between the monitored devices.
The network TAP usually consists of at least three ports, A port, B port and a monitor port. Since network TAP is connected to each port, it still passes all traffic between those two network points but also copies all the traffic to its monitoring port, which allows it to be analyzed without compromising the network.
Network TAPs are usually separated into passive and active TAPs. Passive TAPs usually only copy the traffic from the monitoring ports and can’t receive traffic. This also means that active TAPs have an advantage as they do not present a point of failure in the network. Active TAPs, on the other hand, actively manage the traffic but since these are in-line devices, they need to have fail-safes to ensure that the network is working in any situation like loss of power.
There are also a couple of different versions, or TAP modes, including the breakout TAPs, which uses high-priority monitoring tools to ensure that no packets are lost, filtering TAPs, which allows network administrators to set rules on which data is filtered, aggregation TAPs, which merge traffic streams into a single monitoring port, so-called replication TAPs, which create multiple copies of network data in order to support multiple devices on a single connection port, and bypass TAPs, which prevent in-line security devices to cause a network downtime due to a failure or some other situation.
Network TAPs are commonly used as they receive all of the data and usually do not cause latency or other network issues. Since Network TAPs do not have an IP or MAC address, these devices can’t be hacked and are usually very secure.
While network TAPs are easier to manage and provide much more data than some other monitoring devices, they are usually expensive as they require additional hardware, which could be a big issue for large networks.
There are several other methods to monitor networks and traffic, including simple network management protocol (SNMP), port mirroring, also known as Switched Port Analyzer (SPAN) devices, or similar monitoring protocols like TaZmen Sniffer Protocol (TZSP), which is a low-cost alternative but does affect the performance of a network device.