Industry Insights

Pre-Terminated Cabling Systems - Part II

Wednesday, November 23, 2016 | by Rudy Montgelas

With many preterminated copper solutions, the cables may be terminated with a jack termination.  The patch panels typically are a mounting frame only so there is usually no connectivity.  These cable assemblies may have individual jacks or a cassette end, but in either case, these ends mount to the frames.  A drawback with this is that jacks weren't designed to be put through the rigors that cable goes through when installing it.  Since these links are either a horizontal or backbone link, they will most likely have to be pulled through a pathway.  They are also fairly large, particularly when in a cassette footprint, which makes it difficult to install in tight spaces.


Copper Bifurcated Plug/Jack Termination

Many copper preterm cabling systems utilize modified versions of existing terminations (jacks or multi-ports) resulting in oversized ends that need to be routed through openings in pathways, racks and cabinets.  Using existing terminations also create concerns with cable strain relief and terminated conductor, and protecting connectors from damage during installation.  Although modifications have been made to the cable strain relief to minimize risk of damage, these terminations were not designed to withstand the additional challenges of being pulled in with cable and remain more susceptible to installation-related damage.
In order to make the cable end smaller and more robust, a copper bifurcated plug solution such as Legrand’s copper SNAP™ system, utilizes a 2-piece termination, resulting in a cable end better designed for the challenge of installing cable assemblies while enhancing ease and speed to install.  The bifurcated termination allows the separation of the cable assemblies from the modular jack connections that reside on each end of the permanent link.  This approach allows the use of smaller, more mechanically robust plug connectors on the ends of cable sets.  Smaller connectors are easier to feed through openings. The plug type connection provides a connector that is intended to be moved & handled as part of a cable assembly.  It is better suited to avoid damage during installation. There are no moving contacts that need to be protected in modular plugs, unlike modular jack contacts.

Looking at the same permanent link using a preterminated horizontal cabling plug solution, the patch panels look like standard patch panels from the front.  But the rear portion of each 6-port module is the specially designed jack instead of a 110 IDC.  This is one-half of the bifurcated SNAP connection.  The other half of the connection is the end of the horizontal cable in a plug-style footprint. This design is based on a termination consisting of two parts, the cable end can be kept small and robust making the cable assembly much easier to install.  This type of panel jack must be purchased with the panel because the cable end is only one-half of the connection.

Bundled Copper Cable Assemblies - Stagger:

Bundled copper assemblies usually have three end leg options: no stagger, left stagger and right stagger.  These types of cables are usually available for both horizontal applications and as port replication cables. 

Shown at the top is a port replication cable assembly with no stagger option on the RJ-45 end and the left stagger option on the plug end.  The no stagger option is shown in the middle.  At the bottom is a horizontal cable assembly with a no stagger option at one end and a right stagger option on the other.
Using left stagger or right stagger end legs can assist in organized and neat cable management.  Left stagger ends should be used when the cable enters from the left side on the back of the rack because the shortest leg is usually on the left. 

Right staggers are employed If the cable is entering from the right side on the back of the rack.

The plug and play aspects of these systems also facilitates moves, adds and changes and offers rapid re-configurability where and when it’s needed.

The “no stagger” configuration is used if  the bundle ends are at an even length and can be “fanned-out” out either way from the back of the patch panel.  One thing to note is the port numbering on the panel.   When you are looking at the back of a patch panel, ports are usually numbered from right to left with port #1 as the right-most port and port #24 the left-most port on a 24-port patch panel.


Port Replication

Often, a server or switch is connected to a horizontal patch panel via patch cords. In this layout, administration on the network is done by moving patch cords between server/switch ports and the horizontal patch panel.
A typical horizontal cabling system layout will have a horizontal cable punched down on the back of a patch panel at one end of the link by the switch and another patch panel or workstation jack at the other end. The problem is that the server/switch port (RJ-45 jack) can become damaged with misaligned or repetitive patch cord moves or changes.

Servers and switches are a large part of an IT manager’s budget.  As networks have grown in both commercial applications and data centers, the investment in servers and switches has grown significantly.  A damaged port is very expensive to fix.  Even if the port is not fixed, it is still costly for the customer because of having one less port to use.
Port replication can remove this risk of damaging server & switch ports.  Ports can be replicated by adding a patch panel.  Single-ended solid cords extend the ports by plugging the RJ45 end into the server/switch port and punching the un-terminated end onto the back of the patch panel so that each server/switch port is tied directly to a patch panel port.  Or, port replication can also utilize the bifurcated Plug/Jack termination previously discussed, without requiring a punch down for a quick, easy and reliable preterminated solution. Now, all administration can be done by moving patch cords between ports on the patch panel replicating the switch ports and the patch panel connected to the horizontal cable.  This configuration is supported in the TIA standards as a cross-connection and is defined in ANSI/TIA-568-C.0.