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5 Steps for Tagging Packets in Port Channel Architecture

March 24, 2016

Antiquated infrastructure, slow technology migrations, and limited bandwidth can’t keep pace with the traffic demands of increasingly advanced communications software, real-time data backup solutions, and other high-bandwidth applications.

In other words, both software and demand are always light-years ahead of infrastructure and the human psychology that dictates IT decisions at enterprises—and that gap is widening.

One of the most effective performance solutions for organizations that need more bandwidth, but cannot commit to a full infrastructure migration is port channel architecture. At its most basic, port channel architecture—the generic name for Cisco’s EtherChannel®—unifies up to four separate physical Ethernet links into one link, resulting in a higher-speed connection and increased bandwidth.

But while port channel architecture is an ideal way to support higher demands on networks while enterprises are in the process of migrating their infrastructure, it’s by no means a perfect solution. Because port channel architecture combines up to four separate links into one and enables higher bandwidth than infrastructures would normally handle, it also raises issues with network visibility, traffic monitoring, and security.

Why Is Tagging Packets Necessary for Port Architecture Environments?

Enterprises that utilize port channel architecture need to maintain network visibility to adequately monitor traffic and ensure security. The best way to compensate for the port channel architecture environment’s decreased network visibility is by utilizing technology that tags packets for in-line security applications.

EdgeLens_port-channel-architecture-tagging.png

5 Steps for Tagging Packets in Port Channel Architecture:

1)    Traffic from the four physical links is received by the network TAP and tagged according to its original link.

2)    The traffic is aggregated and load balanced by the network TAP so it does not overwhelm the network, and sent to in-line security appliances such as web application firewalls (WAFs) in a manageable distribution.

3)    The security appliances scrub packets to remove any malicious information.

4)    The security appliances send back the traffic to the network TAP, which removes the tags.

5)    The scrubbed packets are sent to their destination.

This process ensures that port channel architecture environments continue to support and monitor in-line security appliances, guaranteeing safety as well as functionality in this transitional environment.

The Best Tagging Solutions for Port Channel Architecture Environments

One way to support in-line security appliances, such as your Next-Gen Firewall, is through using a network TAP, such as Garland Technology’s FAB, in conjunction with an external network TAP. Another, simpler option is an integrated solution, such as Garland’s EdgeLens® hybrid bypass TAP.

EdgeLens® manages both in-line security appliances and out-of-band monitoring applications, supporting filtering, aggregating, load balancing, and packet tagging for whole-network visibility. Integrated solutions, such as EdgeLens®, are ideal for enterprises that are transitioning to higher speeds and increased bandwidth, and don’t want to invest too much time, energy, and money into overly complicated technology in the interim. 

Learn more about best practices for implementing port channel architecture in your organization by downloading Garland Technology’s free white paper: Maintaining Network Visibility While Implementing Port Channel Architecture.

https://www.garlandtechnology.com/maintaining-architecture-network-visibility-while-implementing-port-channel-lp

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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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