SPECIAL FEATURE test equipment & tools
Fig 3 . Ethernet data frames are sent across the cable or network checking for errors and reporting the actual achievable data rate . the functionality of a Layer 1 qualifier alongside their other network testing capabilities .
It is also worth noting that while ‘ qualifying ’ a cable sounds impressive , this type of device does not provide data to prove that cabling meets the required standards . Qualifiers do not test the cable as such , but conduct simulations to test whether the cable can successfully transmit data from point to point . If you require cable manufacturer warranties or the project specifically requires ( TIA / ISO ) certification , then a cable certifier is required . Otherwise a transmission tester can be used to prove that the cabling infrastructure meets the customer ’ s bandwidth requirements .
Layer 2 detects and corrects physical layer problems , provides Media Access Control ( MAC ), encodes and decodes data frames , performs error checking and synchronises devices with systems .
A Layer 2 data transmission tester should be the choice of technicians who need to measure the successful transmission of data across a cable or through a network .
Data transmission testers for Layer 2 generate Ethernet frames that simulate network data which traverses network cabling and can even be sent through Ethernet switches . The testers generate Ethernet frames with an MAC address that can be read and directed by network switches . The result of the transmission test is a data loss ratio expressed as a percentage of total frames successfully transmitted or the number of dropped frames .
Layer 3 is the network layer which provides data transfer between nodes on different networks ( in contrast to Layer 2 which functions on the same network
Tim Widdershoven is global marketing manager at Ideal Networks . Tim has worked with Ideal Networks since 2014 and has extensive experience in delivering marketing strategies in business to business environments . only ). Layer 3 encapsulates Layer 2 frames inside a data packet , adds source and destination IP address to each data packet and assigns an IP address that is unique to each node on its own network .
Layer 3 testers are almost identical to Layer 2 testers except that they generate an IP packet that encapsulates the Ethernet frame . This packet carries an IP address that can be read by Layer 3 switches and network routers allowing a Layer 3 packet to traverse different networks or different subnets on a single network . Because a Layer 3 transmission tester generates complete packets with IP addresses , it can also be used to test wide area networks ( WANs ) to measure bandwidth between different locations across the Internet .
What about qualifiers ?
This type of tester probably causes the most confusion during equipment selection , likely because field testing standards by the ISO and TIA standards bodies generally address Layer 1 testing only .
Some people mistakenly select a qualifier under the impression that it will conduct Layer 2 network testing . However , qualifiers do not generate Ethernet frames with an MAC address that can be read by active network devices . Therefore , a qualifier is still deemed a Layer 1 tester .
As discussed earlier in this article , whereas a Layer 1 tester measures electrical parameters of the cabling , a Layer 2 device should have the ability to measure successful transmission of data across a cable or through a network . To add to the confusion , many
Layer 2 transmission testers include
Conclusion
With a sound understanding of the layers of network infrastructure , selecting the right tester should be straightforward .
To choose which network infrastructure tester is right for you , simply consider which layer of a network you are working on , and then what you need to test for :
Layer 1 – Choose a verifier to test for correct cable termination OR choose a certifier to provide test reports that meet cable manufacturer warranty requirements . Layer 2 – Select a Layer 2 transmission tester which checks the performance of cabling and Ethernet switches by counting Ethernet frame loss . Layer 3 – Choose a Layer 3 transmission tester which allows you to check the performance between different networks through routers and Layer 3 switches by counting Ethernet packet loss .
Once you are confident which type of tester you need , be sure to review the model ’ s specifications such as size , battery life , speed of operation , ease of servicing and additional features before you buy . Simple benefits such as being lightweight and portable , or having parts that a technician can replace themselves in the field , can make a big difference when it comes to improved efficiency .
It is important to take the time to understand the different types of testers and the models available . After all , you want to be sure that you invest your budget in a tester that meets both your long term needs and your current budget .
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