Re: deploying patch cords

Jul 02, 2025 Last reply: 1 year ago 5 Replies


I have lots of "1-to-1" connections between network appliances.


> I'm trying to think of the most effective (not efficient!) way
> of doing so.
>
> E.g., imagine two switch-like appliances (lots of ports arranged
> side by side). They have to be connected to each other.
>
> One approach is to locate them physically adjacent and use identical
> length cords to connect port 1 to 1, 2 to 2, 3 to 3, etc. This works
> as long as 1 ALWAYS connects to 1 and never, e.g., 18!
>
> When you have more than two such devices, there are other options.
> E.g., imagine a set of 8.
>
> You can interleave them: AaBbCcDd and try tot same 1-to-1 connection.
> With the same caveat.
>
> Or, could create "sandwiches" where half of A goes to half of its
> counterpart "above" with the other half to the counterpart "below".
> Esp for devices with two or more rows of 8P8Cs.
>
> You could lump all of the devices of one type together and
> those of their counterparts: ABCDabcd
>
> Or, not exploit proximity and just put them where they fit: AabcBCDd >
> Its an issue because you have a lot of potential "tangle" as well as
> gaining physical access to ports that may end up buried in a ratsnest.
> The datacenter solution is just to dress the cables off to the side
> and keep the connection faces relatively exposed. That comes at the
> expense of more cable and the difficulty of extracting/inserting a
> cable from that neat bundle. (Recall that I have to address users
> who may be blind or physically disabled.)

The 'sandwich' arrangement will be easiest for a blind person because they only have to remember one linear order of the ports:


ABCDEFG... abcdefg...



There is a risk with the 'sandwich' system that someone could plug an output to another output in the same row.



Another possibility would be to use a matrix with shorting plugs and no connecting leads. If it is imperative that only one-to-one connections are permitted, the sockets could be break jacks to interrupt the connection to all the subsequent jacks in that row or column. (The disadvantage of break jacks is that there are a lot of series contacts to go faulty.)



It sounds as though your problem is very similar to the problems faced by the designers of manual telephone switchboards a century ago. I would look around and see if it was possible to pick up some NOS switchboards - or at least read up on some of the old journals: Bell Labs, POEEJ.

It looks as though a vertical panel with two rows in the same numerical order, with the 'outs' above their corresponding 'ins' and joined by very short interconnecting links in the 'normal' configuration would be the best arrangement. Below that could be a horizontal projecting shelf with much longer leads tensioned with weights so that they could be pulled up and used to make non-standard interconnections. When released they would retract neatly out of the way.

That was the system used in telephone manual switchboards and it worked very well, with the interconnections being easy to trace and no tangles of loose leads.

If you could justify the design and special manufacturing costs, you could go one stage further and make it so that an ''out' and 'in' pair of sockets on one 'channel' were automatically connected to each other in the absence of a plug. That would do away with the short interconnectors altogether. This method was used by the BBC for their apparatus racks, so that only the non-standard interconnections needed external leads.

If standard Post Office Gauge'B' plugs (316-type) and leads could carry the signals without degradation, there have been millions of standard ready-made jack strips with break-jacks already manufactured which will now be lying around as surplus stock. (Grab them before the government tries to buy them all back when they realise manual telephone switchboards are EMP-proof.)

If you provision your installers with a bag of (say) 100x yellow 0.2m cables and a bag of a much smaller number of red 0.5m cables (let's say 4, in this example), the short cables will get used for the vertical links and the long red cables will get used for the links out of sequence. That way the ones that are unordered will stand out and be easy to identify.

I expect that even the dumbest installer is not going to fit links 1-4 with the long red cables and then links 5-80 with the short yellow cables. And there will be a certain physical limit to them crosswiring (port 1 to port 2 maybe, but not 1 to 20) because the short cables won't reach.

Theo

Of course, the ultimate expression of that idea is to use a 90 degree xy matrix, a pin at each join, to route any source to any destination. Add a Z axis multilayer pin to cover multi path source to destination.

Chris

Not applicable to all, but have used the small 10x10 x-y matrix pin boards in the past to patch comms lines, eg: null modem or pin to pin, or combination of such. Visually obvious which pin goes to what as well. One of those glued between a pair of 25 pin D, in one example.

Chris

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