What's up with CAT 7/8 jacks and plugs?

Been doing some structured cabling work lately and a question came up. I always use CAT 7 cable and CAT 6a jacks (mostly keystone). These are RJ-45, or 8P8C if you will. This always made sense to me since CAT 6a keystone modules are the most ubiquitous. But I remember reading somewhere that RJ-45 is not rated for CAT 7, apparently it has to do with the frequency (not the data rate). Instead you would have to use a different connector, GG-45. However, my wholesaler does offer “CAT.8.1 2000MHz RJ-45 keystone modules”, which cost about twice as much as the CAT 6a ones.

So, which is it?

  • Can you use RJ-45 with CAT 7 and CAT 8?
  • Will a CAT 8 keystone jack have a noticably better performance in comparison to a CAT 6a keystone jack (assuming the cable is CAT 7 or CAT 8)?
  • Does anyone ever use GG-45 in the real world? Is it fully backward compatible with RJ-45 (plug and jack)?

I’d appreciate it if anyone has a link to some good resources on this topic.

We use CAT6 or CAT6A. No real demand outside of maybe a data center for anything else.

The GG connector is something new that’s “better” than a standard RJ45. Better in quotes because it might be real, or it might be marketing. I’m seeing plenty of RJ45 cable and jack connectors on the market, just like I have for several years now, this GG variant is new to me and probably just eliminates the 3/6 split to keep the twists tighter (moves 3/6 and 4/5 to opposite corners on the “back side” of the connector). In theory, yes it’s better because you can keep the twists tighter, but one more different connector. The standard goes back to 2007 with updates in 2017 and 2021… Notice how little talk there is about this and so far how little need there is to go to even cat 7 or cat 8 cables in a typical install.

There is a place being built in town that is going to be doing contact work with Netflix and Pixar, they are specify a lot of 40gbps to the workstation, this will of course by on fiber. Honestly I’m not sure why their spec. is 40gbps to the client when they really should be passing workload off to render farms in the server area, but it’s not my contract. Redcode Raw really only needs 10gbps to edit files, so again 40 seems excessive.

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In theory, yes, up to 40Gbps or even 100 Gbps.

No, or at least not just yet, because how many switches or other network equipment with GG.45 connectors have you seen in the real world, or equipment with RJ45 connectors that offers speeds above 10Gbps? If there is any, it’s certainly unaffordable. In practice, fibre is used for everything above 10Gbps and/or long distances.

From all I read about these “standards” I get the impression that Cat 7 and Cat 7a is already dead before it had the chance to become a thing. Cat 8 might become a thing, but as @Tom said is probably only useful in large data centers or maybe in certain environments with special requirements for shielding or whatever.

The average company, even large ones, or home users will not be able to make any use of it, because in most situations even a Cat 5a cable is perfectly capable of delivering 10Gbs over a short distance, and for everything above 10Gbps or long distances they can use fiber, which is well established and therefore much cheaper to implement.

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Multimode price has dropped a lot, you can get a brand new 10gbps SFP+ module for $25, the copper version is closer to $80. The fiber itself is fairly cheap now as well.

That said, the last classroom that we refit I had them put cat6a shielded in so I could step up to faster speeds when the applications required it. Just running gigabit right now, but that could change quickly if requirements change.

Ok, so all of this just confirms my hunch that it’s fine to disregard CAT 7 and CAT 8 jacks und plugs entirely because nobody needs them.

Not that no one needs them, I would have installed cat7 or cat8 in the classroom, but performance per dollar just didn’t fit, especially when I only NEEDED gigabit. I could have gone with cat5e and had the same performance right now but no growth in the future. The cost between 6a SFTP and 5e/6 has dropped enough to where it isn’t a huge sell, the labor still costs more than the cable.

At a minimum, I would run 6a shielded now, this will give you plenty of distance for 10gbps into the future. And 2.5gbps will certainly thrive on 6a SFTP and you are maybe likely to see that in the near enough future that it is probably worth the extra cable cost over 6 or 5e. My policy is to run the fastest cable I can afford when running cable. It is going to be installed for a while, and having the choice to go faster can be helpful as technology changes.

I also find that most 6 or 6a cables are slightly more durable than a lot of the 5e cables that contractors might install. As people go running stuff on top of your ethernet cables, it’s nice to have cable that doesn’t rub through easily.

Those are my thoughts, some people will probably think I’m wrong, some will think I’m right, and some won’t care. Scale of the project may dictate changes to my plans, running 100 IP cameras (compressed streams with 100mbps connections) off of 6a SFTP or higher cable is probably money in the trash, so I’ll tune my requirements to fit the project.

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I’m with you on the higher-grade cable, I don’t do a ton of installs but I always use CAT 7. My question was more about the connectors. If I put a CAT 6a jack on the end of my CAT 7 cable that technically makes it a CAT 6a connection, since this is the lowest-grade link in the chain. But would that even matter in practice, i.e. would a CAT 7 or CAT 8 jack on that same cable enable higher data transfer rates?

I would terminate to the same rating as the cable, then the job is done and ready if you need to upgrade the client speed. Price depending of course.

Stay away from anything CAT7 stuff: it is not a standard and never will be. CAT8 is a standard that will eventually be/is used and that you can rely upon as it is also CAT6/6A backward compatible - CAT7 isn’t.

Cat 7 is an ISO standard but not an TIA standard. If you want to really understand cabling standards better check out my interview with Dan who is on the board that creates and ratifies the standards.

Very interesting! I didn’t know that. I just checked and the place where I buy my cable doesn’t even offer anything lower than CAT 7 for installation cable (they have CAT 6/6a patch cables).

However it seems that the issue of standardization is viewed differently in different parts of the world. In the US, it seems that (obviously) ANSI and TIA carry great weight, whereas in Europe and Germany specifically, ISO and the IEC are more important.

I also just learned that apparently, “cat six a” and “cat eight” mean different things to these organisations, e.g. Cat 6A and Cat 6ᴀ are not the same.