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TAP vs. SPAN: Which Option is Right for You?

Posted on Nov 23, 2023 by
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Capturing network traffic for data monitoring and security analysis is commonly achieved through two methods: using a network TAP (test access point) or mirroring the SPAN port of a network switch. There are notable distinctions between these methods that can impact the integrity of analyzed traffic and the performance of network tools. Understanding the differences between TAP vs. SPAN can help network administrators make informed decisions about which method to use.

TAP vs. SPAN: What Are They?

Network TAPs are usually hardware devices sitting in a network segment, between two appliances (router, switch, or firewall), and allow you to access and monitor the network traffic. A basic TAP has a minimum of four ports. The two "Network Ports" connect to the link endpoints and provide a non-intrusive pass-through for data traffic. The two "Monitor Ports" hand off copies of the link traffic to the monitoring tools.

TAP Deployment

 

SPAN (Switch Port Analyzer) refers to port mirroring. It is a designated port on a network appliance (switch), which sends copies of data traffic on specific ports or VLANs to network monitoring tools. It is a feature of a managed network switch that allows a network administrator to monitor traffic on a specific switch port.

SPAN Deployment

TAP vs. SPAN: Advantages and Disadvantages

  TAP SPAN
Advantages 1. Complete Visibility: Network TAPs offer complete visibility into the traffic flowing through a network. They can capture both inbound and outbound traffic, including all layer 2 and layer 3 packets.

2. No Packet Loss: Network TAPs Make a 100% full duplex copy of network traffic without altering the data.

3. No Configuration Required: Network TAPs are plug-and-play passive devices that do not require configuration or management for network switches.

4. Greater flexibility: Network taps can be used with any type of network infrastructure, including switches, routers, and firewalls. They can be placed on any link that needs to be monitored.

1. Cost-Effective: Network SPAN ports are built into most network switches, which makes them a cost-effective option for monitoring network traffic. No additional hardware cost is involved in deploying them.

2. Scalable: SPAN ports on switches can be configured to monitor multiple ports simultaneously, making them scalable for larger networks.

3. Remote Access: SPAN is a software-based solution, monitoring devices can be located remotely, providing greater flexibility for network administrators.
Disadvantages 1. Higher Cost: Network TAPs are more expensive than SPAN ports on a network switch because they are specialized devices that require additional hardware.

2. Physical Installation: Network taps require physical installation, which can be time-consuming and disruptive to network operations.

1. Packet Loss: SPAN ports can cause packet loss or delay because they operate at the switch level and rely on the switch's processing power to copy and forward traffic.

2. Incomplete Visibility: SPAN ports may not capture all traffic flowing through the network because they are configured to monitor specific ports.

3. Configuration Required: Configuring SPAN on switch ports can be complex and time-consuming, especially for larger networks with multiple switches.

TAP vs. SPAN: Which Approach Is Better?

Both Network TAPs and SPAN have their advantages and disadvantages when it comes to capturing network traffic. In today’s modern high-speed networks, network TAPs are the recommended choice due to their ability to offer complete visibility with no packet loss or delay. When speed and reliability are crucial, TAPs are the better option. However, they can be more expensive and less scalable than SPAN. Consequently, in certain situations, TAPs may not be practical.

SPAN is an economical and scalable solution, suitable for occasional low-cost reactive troubleshooting on underutilized links. This ease of configuration and lack of up-front cost makes port mirroring an attractive proposition for organizations taking their first steps toward network observability. If you want to learn more about SPAN, you can visit Port Mirroring Explained: Basis, Configuration & FAQs.

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