permanent link test
A permanent link is a fixed part of the channel, in other words, the constant part of the channel. This means that it does not include terminal jumpers or device wires. In a data center, the permanent link is usually patch to patch. In a local area network, it usually goes from a patch panel in a telecommunications room to a work area outlet or consolidation point. The maximum permissible length of a permanent connection is 90 meters.
Permanent link testing is preferable to channel testing because it is considered the true foundation of the network. Since proper data transfer relies on the performance of the entire channel, this may seem counterintuitive, but since the jumper is the weakest link, the industry standard provides more headroom in the channel. This means that when using high-quality patch cords for channel testing, the channel will pass the test even if the permanent link fails. This is not a good thing because the last thing you want is a problem with the fixed part. Also, patch cords and equipment cords are handled and moved around a lot, and they may be purchased from different (and sometimes lower quality) suppliers as they tend to be considered commodities. Testing permalinks is the best way to ensure performance when installing (and the best way to prove your work).
The Permanent Link Adapters included with Fluke DSX Series testers use the highest quality cables and reference plugs to ensure that passing permanent links can be reliably configured into passing channels by adding quality patch cords.
Since patch cords are often the weakest link, it may sometimes make sense to sample test them, especially if they are from different vendors, or if the channel test fails but the permanent link passes. Fluke Networks' DSX Series Patch Cord Test Adapters can be used to certify Category 5e, 6 and 6A copper patch cords to TIA-568-C.2 and IEC 61935-2 standards. These adapters include measuring the performance of the plug adapter connection on both ends to verify the performance of the RJ45 plug, which is not verified in channel testing.