![]() ![]() If dark fiber or extra copper runs are available, a tap can be deployed remotely in a building or on a campus, with the Monitor Port data being sent via “home run” to the location of the tool. Also, they are not tied to the physical location of a switch. They provide information about the specific activity on the link, rather than just showing what is coming from the switch. TAPs can be placed on in any link that needs to be monitored. SPAN ports identify these as “bad packets” and discard them. Network troubleshooting often involves using packet sniffers to examine the number of runts, fragments, and CRC’s. In some instances, initiating a SPAN session when a switch is being heavily utilized can impact performance of the switch (this is generally the case with smaller switches such as work group models, and not true of robust core switches.) ![]() If a switch is heavily utilized it will drop SPAN packet copies rather than risk dropping real time data.Ģ. Packet loss due to oversubscription – network switches prioritize real time data traffic over SPAN traffic. Little to no risk of packet loss caused by high utilizationĭuplex non-aggregated TAPs pass every packet through to the Monitor Ports with zero risk of loss (aggregation TAPs may present a small risk of oversubscription.) If a SPAN port has a large volume of data being sent through it, there are two distinct risks:ġ. securities trading) it cannot be done during weekday business hours. In many environments, this requires a scheduled Change Control window, and in some industries (e.g. Once installed, it will always send data from that link to the tools of your choice SPAN ports must be configured each time you wish to change the source (ports or VLANs) sending data to the tools. ![]() More feature rich taps may require initial configuration of a management port and monitor ports, but this is typically done only once – at time of install. The simplest TAPs need only to be physically connected to the cabling between link endpoints. Let’s examine those before assessing the benefits of SPAN ports. The advantages of using TAPs rather than SPAN ports for monitoring tool access are myriad. Variations include TAPs with the capability to merge data from both sides of the duplex link (aggregation TAPs,) the capacity to send multiple copies of the data to a variety of tools (regeneration TAPs,) and models that tap multiple links in a single unit (multi-link TAPs.) These will be discussed in detail in a future installment of this series. A simple duplex TAP hands off copies of the data coming from one endpoint device out the first monitor port, and copies from the other endpoint device out the second monitor port. The two “Monitor ports” hand off copies of the link traffic to the monitoring tools. ![]() The two “Network ports” connect to the link endpoints and provides a non-intrusive pass-through for data traffic. a switch and router, firewall and router, etc.) A basic TAP has a minimum of four ports. TAPs are dedicated hardware devices providing access to the data flowing on a fiber or copper link between two network devices (e.g. Cisco also offers Remote Switched Port Analyzer (RSPAN,) allowing SPAN ports on remote switches to be brought back across the network to the SPAN port of the primary switch, to which the tool is attached. Websense.) Port mirroring on a Cisco Systems switch is generally referred to as Switched Port Analyzer (SPAN.) Other common terms for this feature include Port Mirroring, but SPAN has become a generic industry term, regardless of switch manufacturer. It refers to port mirroring, as used on a network switch, which sends copies of data traffic on specific ports or VLANs to network monitoring tools. SPAN was originally defined by Cisco as an acronym for Switch Port Analyzer. ![]()
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