This chapter weighs the pros and cons of Method B of the TIA-568 cabling standard.
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- Chapter 1 - Introduction to challenges for polarity in data centers
- Chapter 2 - Understanding MPO polarity
- Chapter 3 - Knowing the standards
- Chapter 4 - Optics from 10G to 400G
- Chapter 5 - Disadvantages of Method A TIA-568
- Chapter 6 - Analyzing Method B TIA-568
- Chapter 7 - Analyzing Method C TIA-568
- Chapter 8 - Introducing the multi-path solution
- Chapter 9 - Real-world examples of how multi-path works
- Chapter 10 - The advantages of a multi-path solution
Rick: Switching over to talking about method B, again, a lot of companies and a lot of customer data centers utilize method B. It's a good system. However, the most, I think, thing that stands out drastically with method B is that in a duplex scenario, meaning a trunk cable into cassette modules, you have to have an A side and a B side set. Now, me ... Sometimes I'm scatterbrained, so if I was implementing this into my system, you know, if I needed 30 cassettes, I need 15 of one kind of cassette and 15 of another kind of cassette and I have to make sure that 15 are implemented on one side and 15 are implemented on another side.
I think I can do it, but sometimes some of the people that I've hired over the years might have a challenge with that, and may not be plug and play like you were saying earlier.
Josh: No, it's not so much.
Rick: But, the good news with this is that at least I only need one style of jumper. So at least ... At least that's good.
Rick: But now let's take a look again on the right hand side. Okay, now we need parallel optics. Okay? Well, again, take a look at two things that stand right out to you, okay? First of all, all the stuff into my trunk now needs to become A male. Well, there's very few options out there with installed base that you're able to switch these genders of these particular connectors. So long and the short of it is, now you have to buy a jumper that has male on one side and female on the other. Again, it will work in the system there when we pull these cassette modules out. However, it will not work with a machine to machine plug-in, for example, or a spine and leaf plate connection. A switch ... A lead switch to a core, you can't plug that in, you can't utilize the same jumper. Or you might have, you know, Tony the installer or a guy working for you try to jam this male plug into your thousand dollar 100 gig transceiver and damage some things. Okay?
So inherently again, all challenges. And I didn't even bring up the ... What I think really is ... Which really makes method B a non-usable system, is that there's an ender out there that has a patent on the intellectual properties of fiber paths for single mode version of this. Again, not to get too techy, but in the single mode version of the MPO interconnects, the MPOs actually have to be keyed. That's required because of the Farrell pipe and things of that sort of ... And the laser transmissions. But anyway, they're made with an eight degree angle, that's standard. But you take a look again at the scheme, you'll see the adapters there with MPO. Now again, the MPOs are not only key ... Or, I'm sorry, not only have genders associated with them, but they're also keyed.
Rick: So these adapters, obviously, have to have keys on both sides. So the method B adaptor that's spec’ed in the system is a key in to key up. What do you think happens when you plug the key up to key up angle MPO connector together?
Josh: You're gonna have an air gap.
Rick: A big air gap. That's not good. Angles are gonna hit each other, right?
Rick: So then, you basically have to go out and find a proprietary cable that builds something away from what's supposed to be standard, besides the gender to worry about that we already talked about, in order to try to make this system work. Now why don't I bring this up and say, "Well, no." Because again, short range single mode is becoming a big factor in data centers. Right now, the average call, so short reach single mode for a hundred gig, is about on par with multi-mode transceivers. And we all know that the single mode infrastructure is probably about 70% of that of multi-mode.
Rick: And then OM4. You know, and obviously OM5 ... The costs are high right now because it's a new technology, so yeah. It's probably more than 50% less expensive than OM5. So, that's one thing to consider.