Patch cords are your weakest link

Patch cords are your weakest link

14 August 2014 | Reading Time: 2 minutes

Finding the weak link in your cabling

It’s a commonly known fact in the cabling industry that patch cords can be the “weak link” in any end-to-end infrastructure solution. Like anything in life, weak links need to be repaired in order for any solution to work effectively.

Historically, many businesses focused on the cable performance when making decisions on infrastructure. However, as cabling systems have evolved, connectors and patch cords have become significant contributors to deteriorating efficiency. The fine tuning of these high performance components is required to enable reliable, predictable performance every time, needing to be tuned not only to each other, but also variation control techniques.

Testing and Standards

The testing of installed cabling has gained wide acceptance, and technological advances mean that testing up to 500 MHz is routinely performed quickly and accurately, even when undertaken in the field. However the Permanent Link, the most widely used test configuration, was developed using standards to verify the performance of the installed link from the patch panel to the work area outlet. In other words, it specifically excludes the patch cords.

Most customers would assume that the addition of a ‘standards compliant’ cord would guarantee the delivery of the end-to-end performance requirement. Why would they think otherwise? How can such a simple looking, off-the-shelf product make a difference?

Standards are improving

Significant advances have been made to cabling standards over the last few years, including the specific requirements for components that are intended to deliver the expected end-to-end performance even when they are in a mix-and-match environment.

It is important to note that the standards specify minimum requirements only. They don’t cover all of the coupling and reflection effects that can occur within or between components. In addition, ‘standards compliance’ is a self certification which means anyone can make the claim, it is often up to the customer to decide if they believe these standards.

Overcoming ‘weak link’ concerns when designing patch cords

Patch cords are constructed with flexible cordage and a modular (RJ45) plug at each end. In order to deliver optimal performance, the characteristics of the cordage are carefully matched to the plug, including jacket type, thickness and overall outer diameter. The orientation of the pairs at each end prior to termination, the twist rate, the insulation diameter and the conductor diameter are among many others characteristics that need to be considered when designing a patch cord.

A poorly assembled plug will deliver an inconsistent performance and may even exhibit intermittent continuity – a network manager’s worst nightmare! In some extreme cases, badly assembled plugs have even been known to damage the contact pins in cabling or switch ports, for example when the plug ‘blades’ are loose, too high or out of alignment.

The arrangement of each cable pair inside the plug must also be carefully controlled. This enables system vendors such as CommScope to tune jacks and plugs to achieve optimal performance, above that of the minimum standard requirements.

Using just ‘any patch cord’ in a system may not only degrade performance but may prove to be a costly mistake in the event of a system failure. Any system is only a sum of it’s parts, so ineffective parts can cause many more problems that you might initially expect.


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