25Gbps over CAT6A?

[Kevin Peters]

Does anyone have any experience of running 25 or 40 Gbps over CAT6A? I know the standard doesn't officially support it but I am interested if it is possible.

The reason for the question is that I have a new 10Gbps server arriving and have discovered that one of my buried 5e cable drops (to my office) will only connect at 100Mbps. Before I do another cable run (on the outside of my house) I'm just wondering what the real world limits of CAT6A are for the future. Conduit runs are no longer an option for me.

That said CAT6A might be my only option as CAT8 reels seem to only come in one colour (blue) and don't seem to be designed for long runs, just for patch cables.

 

[NablaSquaredG]

I don't think you'll have any luck with 25G / 40GBase-T over CAT6A.

Wouldn't it be more future proof to use fibre instead of copper?
An OM4 / OM5 MTP / MPO cable is definitely future-proof and allows you 100GBe without any hassle.
40G Transceivers are pretty cheap too.

 

[Kevin Peters]

Thanks @NablaSquaredG. You are probably right, but someone must have tried it! Maybe it's something for @Patrick to try in a video?

I am considering fibre but it's all new to me... Question for you: I believe that fibre cables come pre-terminated with connectors, so even though the cable is narrower you would need to drill wider holes to run through joist etc. Is that right?

Also I must confess, despite being experienced with copper networking, to be thoroughly confused by fibre. If I run a OM4 cable from my server cupboard to my office, I assume I need a OM4 to SFP+ transceiver module for my switch in the cupboard, but how do I get the other end into my iMac? I don't see any sort of USB3 to OM4 network adapter so I assume I'll need a media converter box?

Thanks for your patience!

 

[NablaSquaredG]

You are probably right, but someone must have tried it!

I don't think there is even 25GBase-T, let alone 40GBase-T or 100GBase-T hardware available... Considering that there were already huge issues with 10GBase-T on RJ45, I don't think 25GBase-T is going to be available anytime soon

I am considering fibre but it's all new to me... Question for you: I believe that fibre cables come pre-terminated with connectors, so even though the cable is narrower you would need to drill wider holes to run through joist etc. Is that right?

Yes, usually they come pre-terminated, because splicing fibre to a plug is a difficult and error-prone process. Although there are some field type plugs available (LC Plugs), but you won't have any luck with MTP without the right tools.
For an example on how to install an MTP plug, see here:

but how do I get the other end into my iMac? I don't see any sort of USB3 to OM4 network adapter so I assume I'll need a media converter box?

There are two options:
Media converter or a network card like Mellanox ConnectX-3, where you can plug in another SFP+ / QSFP+ Transceiver

 

[Kevin Peters]

Thanks, that makes more sense. I assumed that 25GBase-T existed, given CAT8 but now I understand.

My iMac has no PCI slots so the Mellanox wouldn't work. I found some thunderbolt -> SFP+ boxes but they are expensive even at 10Gbe!

So my options seem to be:
Cheaper, short term is to run CAT6A and max at 10Gbps.
More expensive, longer term is to run OM4, knowing it will last me up to 100Gbps and perhaps more, but deal with adapters and external boxes in the short term.

Thanks for your help!

 

[BackupProphet]

The cheaper long term is fiber. Why do people think fiber is expensive? I would never ever consider CAT6A unless backward compatibility was an issue.
Not to mention all the other advantages like power efficiency and improved latency.
My biggest issue with fiber is custom termination but in practice, it's not a big deal.

 

[Kevin Peters]

Hi @BackupProphet, thanks for your input. Sorry, my post should have said: "More expensive (short term) BUT will last longer".

 

[Tom5051]

If you want a smaller plug to go through holes, look at OS2 simplex fiber (cheap) and BIDI transceivers (about twice the cost of a regular transceiver but as the name says they are bi-directional). It only use a single fibe instead of a pair.

 

[Tom5051]

Also single mode fiber is more resistant to future technology, it's been the same for many years. A company I worked for put down OM2 multimode, under a hangar and airpiort tramac. come 10G they found they had 350m of distance and no transceivers would work. Multimode was a thing because it used to be cheaper to buy transceivers but that is no longer the case. Also 100G uses MTP cables which while OM4, uses many pairs and a totally different plug/socket to 10G and 25G

 

[Tom5051]

Take a look at fs.com if you want to see all the different technologies on offer, I spent days looking at cables etc. Good fun

 

[Kevin Peters]

Thanks @Tom5051 I actually was already having a look at fs.com already.

Sorry, one last question. With copper cables you terminate them at a wall socket or patch panel and then have a separate patch cable to the computer/switch etc. With fibre it seems that each end plugs directly into the computer or switch - is that right? If that's the case if you drill through a wall, what do you have on the wall on the inside rather than a socket? Do you just use a brush plate to keep things tidy?

 

[BackupProphet]

fiberstore.com has wall socket for fiber cables that is like a nice looking patch panel. I am planning to get one of those for my living room, or just a small white box where I can pull out the cable. As Tom5051 is mentioning, a bidi transceiver with a single fiber cable is better when you need to make small holes in the wall where you want to pull the cable through.

 

[Tom5051]

I just use a blank plate and drill a hole but you can get keystone inserts

 

[BoredSysadmin]

"my buried 5e cable drops (to my office) will only connect at 100Mbps." - I'd check both sides of that cable run termination points and jump cables if you're using any. cat5e correctly terminated should be easily running 1g for long distances and even (unofficially) 10g for short runs.
getting cat5e tester is easy and cheap

 

[Kevin Peters]

Yeah it's strange @BoredSysadmin. I have about 16 of them and this is the only one that doesn't connect at 1Gbps. I have visually checked each end but perhaps a cheap tester would make sense! My only thought is that I have somehow damaged it in some recent renovation work I did.

 

[apnar]

Why choose? Run both . Use the cat 6a cable now but you'll have the fiber there for later when you need more speed.