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The 101 Series: Filtering TAPs

February 22, 2018

filtering network taps garland technology cybersecurity

In our 101 network TAP series, we have explained the functionality of the various network TAPs that are available to gain access to the traffic that is typically found in a network. We have reviewed passive fiber TAPs, copper network TAPs, aggregation TAPs, SPAN/regeneration TAPs and the bypass TAP.  

Now we want to review the ultimate way to optimize your visibility fabric – deploying advanced data filtering with packet broker functionality in a TAP. 

 

Filtering Capabilities

A network TAP will copy all of your data – every bit, byte and packet on your network. But sometimes your tools don’t need to see everything. Your VoIP or Wireshark only needs to see the traffic required to do its job. In this case we need to add the additional technology of filtering. When we are not interested in all the traffic that is going through the link, we can filter out what is not required by the tool – this ensures we will not oversubscribe the monitor ports.

This scenario (below) shows four 1G links with a filter applied and then aggregated together and sent out port D on TAP four to the monitoring or security tool.

Filtering TAPs by Garland with Port Mapping

Port Mapping for Maximum Efficiency

Port mapping (aka: filtering backplane) on the new XtraTAP: All-In-1 Chassis is an important feature because it allows you to aggregate low traffic links such as 1G VoIP links together. You can aggregate up to four 1G links to send to a VoIP analyzer and use only 1 port on the analyzer. This benefit minimizes of the number of monitor ports required on the monitoring tools and appliances.

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Of course, when aggregating the traffic of multiple links there is the possibility of oversubscribing the TAP’s monitoring ports. To eliminate the possibility of oversubscribing we need to filter out the traffic that the monitoring appliances are not interested in, we do this with rule-based filters (see below). We also have the option to not apply a filter by sending all the data to a critical appliance like an intrusion detection system (IDS).

Port Mapping via a Backplane Filter with Garland's new 1G Packet Broker System

Smart Filtering and Aggregation

The XtraTAP: All-In-1 provides the capability of filtering network traffic at Layers 2, 3 and 4 of a packet. Providing the monitoring tools with only the traffic that they are interested in and creating efficiency to do only the processing they are designed for.

So, being able to aggregate the links together is good and then filtering out the traffic that the monitoring appliances are not interested in is better. 

Today's blog is all about the filtering capabilities in our new chassis system. However, this new 1G wonder box can do it all because it supports all of Garland's modular TAPs, including: copper network TAPs, aggregation TAPs, SPAN/regeneration TAPs and bypass TAPs.

Garland Technology's, The 101 Series is an educational series on how network TAPs work and the different functions they provide to the overall network design for access and visibility.

Looking to add a visibility solution to your next deployment, but not sure where to start? Join us for a brief network Design-IT consultation or demo. No obligation - it’s what we love to do!

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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.

NETWORK MANAGEMENT | THE 101 SERIES