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Not Ready for the 10G to 40G Transition? Consider Cisco's EtherChannel

March 10, 2016

Large enterprises know they will eventually have to make the transition from 10G networking to 40G if they want to overcome the challenges of big data and bandwidth-hogging applications. But boosting bandwidth quickly would require replacing cable infrastructures, purchasing new connectors, and addressing significant monitoring challenges.

Faced with these hurdles, some companies aren’t ready financially or structurally to make the full transition.

Cisco, a Garland Technology partner, offers a way for companies to make a gradual shift in networking speeds by aggregating port links with EtherChannel, Cisco’s port channel architecture technology. Several physical Ethernet links can be grouped, creating one logical Ethernet link that provides fault tolerance and high-speed links between switches, routers, and servers.

 Easing Into Faster Networking Couldn’t Be Easier

There are numerous advantages to using EtherChannel as a stop-gap measure while you’re working out the logistics of a complete transition to 40G. 

  • A single network presence holds the network bandwidth of all adapters. If one adapter fails, network traffic can be sent automatically on the next available adapter without affecting existing user connections. When the failed adapter recovers, it is automatically returned to service on the EtherChannel.
  • Your network element connectivity won’t be limited to one link. EtherChannel supports up to four links, with incremental trunk speeds from 10G up to 80G. If a link fails, traffic is automatically redistributed across the remaining links. The recovery takes less than one second and is transparent to network applications and end users.
  • Depending on your hardware platform, you have several options for implementing source-to-destination load balancing across the physical links that are part of the same EtherChannel.
  • EtherChannel relies on existing switch ports, so you don’t need to upgrade the switch-to-switch link to a faster connection. Most configuration tasks can be done on the EtherChannel interface instead of on each individual port, so configuration will be consistent throughout the switch-to-switch links.
  • Because EtherChannel leverages existing wiring, it is easily scalable. You can use it at all levels of your network to create higher bandwidth links as the traffic needs of your network increase.

Increasing the flexibility of your network’s bandwidth allows you to bridge the gap between infrastructure migrations without succumbing to dropped packets.

Port Channel Architecture is the Right Stop-Gap Measure

 Many companies try to scale bandwidth by just adding more 1G links to the network connection. But some routing and switching protocols see them as redundant and render them inactive. Newer protocols support seemingly redundant links and still protect against loops. But because they exist in the data link layer of the network, their ability to expand network capacity is limited.

EtherChannel uses the network layer of the OSI stack model to give you greater flexibility in network design. Physical links between network elements are aggregated to virtually scale bandwidth capacity without causing problems with redundancy. Cisco’s EtherChannel technology is based on a proprietary port aggregation protocol (PAgP), but it can be accessed by any company, not just Cisco shops.

The scenerio below depicts tagging, aggregating and load balancing with Cisco's ASA NGFW. To learn more, view our Joint Solution Brief.Cisco_EtherChannel_with_Garland_EdgeLens.png

Keeping an Eye on Traffic In and Out 

The key to successfully implementing EtherChannel is understanding how to configure the technology to monitor traffic with out-of-band appliances while ensuring visibility for in-line security appliances. Our network TAPs provide a  physical connection between your network and your security and monitoring appliances, while giving you 100% visibility into your network.

Download our report on Maintaining Network Visibility While Implementing Port Channel Architecture to learn how you can gradually ease your company’s transition to 40G networking.

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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