Chapter 2 - Introduction To Network Taps; What Is A Network Tap - Network Critical SmartNA-X User Manual

I
NTRODUCTION TO NETWORK
2 –
This chapter provides a brief introduction to network TAPs, for those users who haven't used TAPs before. It
covers the following major topics:
• What is a network TAP?, page 10
• Suitable locations for placing TAPs, page 11

What is a network TAP?

At Network Critical we define a network TAP as a "Test Access Point", or a hardware device inserted at a specific
point in the network where data can be accessed or "sniffed".
A simple TAP copies traffic from a live network to a monitoring port, where it can be monitored or captured for
later analysis. With more advanced TAPs, such as those from Network Critical and used in SmartNA-X systems,
traffic can be aggregated from several input ports and replicated to one or more output ports. In addition, you can
employ packet filtering to reduce the amount of traffic reaching the network tool, thus allowing the use of 1G
tools on high capacity networks.
TAPs are inserted between two nodes in a network, such as between a switch and firewall. The network cable
between points A and B is replaced with a pair of cables, which are then connected to the TAP
is actively routed through the TAP, without the network's knowledge. This allows the TAP to make a copy of the
traffic, which is sent out of the monitoring port to be used by another tool without changing the network traffic
flow.
To Live Network
Device A
Figure 2-1 Tapping live network traffic
A B C D
To Live Network
Device B
DRAFT
2
C
HAPTER
TAP
S
(Figure 2-1). Traffic
10