Wireless Networking Limits - Part 3 of 3 - Gigabit Cable Lengths

By: John Fredrickson on September 12th, 2014

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Wireless Networking Limits - Part 3 of 3 - Gigabit Cable Lengths

wireless  |  5.8 GHz  |  avalan  |  300 Mbps  |  Ethernet cable  |  Cable length  |  gigabit speeds  |  Radios  |  cables  |  CAT6  |  tech support

At AvaLAN Wireless, we have done our best to design our products in such a way as to push the limits of possibility, sometimes even venturing into the realms of the unfathomable. However, the Laws of Physics and the Universe still govern much of what we can and cannot do. We still have limits. The trick to making the most of our products is to know those limits. Knowing your limitations is not just beneficial to your project, it is crucial to its success. Knowing your limitations will save you time, money, effort, and especially frustration.

In Part 1 we looked at the line of sight limitations of the 300Mbps 5.8GHz Radios (AW58300HTA, AW58300HTS, and AW58300HTP-PAIR) and in Part 2 we explored the mechanics of throughput. In Part 3, we will discuss recommended Gigabit cable lengths for these radios.

Network Cable Length Limits at Gigabit speeds 

CAT6 75 BLU unitTo get the most of out the potential throughput of your Ethernet cable, a correct understanding of an optimal setup is necessary. Many aspects of cabling setup will significantly affect your total potential throughput. Some of these aspects include cable length, junction points, and cable type. To get the most out of your wired throughput, we at AvaLAN Wireless, recommend that you use a maximum of 20 meters of continuous CAT 6 cable between your radio and the POE Injector. This recommendation is based on our experience and Electrical limitations that are inherent in wired network interfaces. AvaLAN Wireless’s 300Mbps 5.8GHz radios can negotiate over their wired Ethernet interface at up 1Gbps and therefore have a few extra limitations in comparison to our 100Mbps radios that work at a maximum of 100Base-T. Because these radios auto-negotiate, when circumstances are unfavorable, they will negotiate down to the next lower Ethernet interface speed. The longer the cable run, and the more junctions at which cables connect to each other, the more attenuation there is to degrade the signal and potentially impair data consistency. This is particularly problematic when this wiring is not a continuous cable run.  Keep in mind that AvaLAN’s POE injector itself acts as a junction. If more than 20 meters of cable is used, then the radio may auto-negotiate to 100Base-T data rates and typically function at this speed for a maximum of 100 meters. However, under these circumstances we have seen occurrences of the switches’ port rate toggling between the lower and higher rates causing inconsistent network performance. We recommend not exceeding the 20 meter length to ensure optimal performance at Gigabit speeds.

Notwithstanding the limitations of the 300Mbps 5.8GHz radios, when configured and used properly, they tend to exceed the expectation and needs of our customers. Thank you for choosing AvaLAN.

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Written by John Fredrickson