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Network Visibility Fabric Design - Focus on the Core

June 13, 2019

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We’ve previously talked about the importance of the access layer, aggregation layer and edge to a well-designed network visibility fabric. Tapped traffic from the access layer flows to the aggregation layer, where it’s collected, processed, and then forwarded to the core of the fabric. 

The core of the network visibility fabric is where one or more network packet brokers (NPBs) collect and process all flows. It’s in the core that advanced packet processing takes place to send specific data to various monitoring, forensics, and analysis tools. In addition to packet brokering, advanced packet manipulation such as deduplication, decryption, time stamping, packet slicing, and load balancing are critical functions in the core.

Decryption

According to EMA research, 45% of enterprises state that the most critical packet manipulation feature for network operations monitoring, is decryption. The majority of network traffic today is encrypted, but packet analysis requires decrypted flows to provide visibility to IT teams. To resolve this issue, network engineers have a few options when it comes to decrypting network traffic; configure individual tools, offload to a NPB, or add a dedicated box to handle the decryption. Each of these options has positives and negatives that must be taken into consideration when designing the network. Configuring capable existing tools to perform decryption may be cost-effective, but adding this additional feature can degrade the performance of the tool over time. Relying on your NPB may be another option if your vendor provides a box that has this feature, but in addition to added performance strain, it will likely require an expensive license and additional fees on top of what you’ve already committed to. Finally, choosing a best-of-breed solution, means selecting a dedication box to perform the decryption needed to analyze network traffic. While you’re adding an extra cost to perform this critical feature, you’re ensuring that the rest of your network operates in an effective manner. 

Read EMA's Best Practices for Building A Network Visibility Fabric!

Deduplication

Out-of-band security monitoring tools need to ensure that they are only seeing one copy of network traffic. It’s for this reason that deduplication either by session ID or metadata generation is important to 44% of enterprises today. Options to implement deduplication include adding a stand-alone box, or seeing if your NPB vendor has the option to add deduplication as a feature to your NPB.

 

Load Balancing

Load balancing, also referred to as traffic distribution technology is a method of tailoring your available resource to make sure capacity meets nemands. 41% of enterprises rely on L2-L4 load balancing at the core to split network traffic between multiple tools in a manner that doesn’t result in duplication of traffic and helps to prevent oversubscription of the ports. 

Garland Technology has taken the approach to deconstruct the network packet broker. Essentially this means that rather than having one box do everything from the packet brokering to the deduplication, we’ve designed products and formed partnerships that handle specific functions to meet the needs of our customers. Our PacketMAX™: Advanced Aggregators combined with Advanced Features boxes to handle deduplication, packet slicing, or time stamping, can meet customers’ needs today and grow with them as their needs evolve over time.

[Want to learn more about the components of a network visibility fabric? Read the latest whitepaper from the analysts at EMA, Best Practices for Building a Network Visibility Fabric.]

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Heartbeats Packets Inside the Bypass TAP

If the inline security tool goes off-line, the TAP will bypass the tool and automatically keep the link flowing. The Bypass TAP does this by sending heartbeat packets to the inline security tool. As long as the inline security tool is on-line, the heartbeat packets will be returned to the TAP, and the link traffic will continue to flow through the inline security tool.

If the heartbeat packets are not returned to the TAP (indicating that the inline security tool has gone off-line), the TAP will automatically 'bypass' the inline security tool and keep the link traffic flowing. The TAP also removes the heartbeat packets before sending the network traffic back onto the critical link.

While the TAP is in bypass mode, it continues to send heartbeat packets out to the inline security tool so that once the tool is back on-line, it will begin returning the heartbeat packets back to the TAP indicating that the tool is ready to go back to work. The TAP will then direct the network traffic back through the inline security tool along with the heartbeat packets placing the tool back inline.

Some of you may have noticed a flaw in the logic behind this solution!  You say, “What if the TAP should fail because it is also in-line? Then the link will also fail!” The TAP would now be considered a point of failure. That is a good catch – but in our blog on Bypass vs. Failsafe, I explained that if a TAP were to fail or lose power, it must provide failsafe protection to the link it is attached to. So our network TAP will go into Failsafe mode keeping the link flowing.

Glossary

  1. Single point of failure: a risk to an IT network if one part of the system brings down a larger part of the entire system.

  2. Heartbeat packet: a soft detection technology that monitors the health of inline appliances. Read the heartbeat packet blog here.

  3. Critical link: the connection between two or more network devices or appliances that if the connection fails then the network is disrupted.

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