why haven't ethernet connectors changed?

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21

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I was looking at a Raspberry Pi board and was struck with how large the ethernet
connector is in comparison to the board as a whole. It strikes me:

ethernet

connectors haven't changed that I'm aware in pretty much 25 years.

Every other

cable has changed several times in that time frame. I imaging that if

anybody

cared, ethernet cables could be many times smaller. Looking at wiring

closets,

etc, it seems like it might be a big win for density too.

So why, oh why, nanog the omniscient do we still use rj45's?

Mike

The connector is to ubiquitous to change. Other vendors have addressed
the space issue by not supporting Ethernet, but forcing the use of a USB
dongle (Macbook Air comes to mind).

22

Because they *work*.

How much trouble do we have with USB or HDMI connectors coming loose?

Also, RJ45 is around the minimum size where you can hand-terminate a
cable. How would you go about quickly making a 36.5 foot 8 conductor
cable with, say, micro USB ends?

Regards,
Bill Herrin

23

You're assuming that that's a universal requirement. Most people
in retail situations just buy the cables, or they are shipped with the
widget. They're also pretty used to being screwed over by greedy
manufacturers for whom cable churn is a profit center (I'm looking
at you, Apple).

Mike

24

Thin net (50 ohm coax w/ BNC connectors) was ubiquitous once too. RJ45
with twisted pair had little trouble displacing it because it was much
better.

Every alternative I've seen to the RJ45 connector has been deficient
in some major way. Hard to field terminate. Pulls loose too easily.
Breaks if you look at it wrong. Etc.

On the other hand, I wonder if it would be worth asking the 802.3
committee look at defining a single-pair ethernet standard that would
interoperate with a normal 4-pair switch. So, you'd have two
conductors into some kind of 2P2C micro-RJ connector on one end of the
cable but into a full RJ45 connector on the other. A single-pair pair
cable would run at best at a quarter of the speed of a four pair cable
but for something like the Raspberry Pi that's really not a problem.

Regards,
Bill Herrin

25

Yeah, that's kind of along the lines I'm thinking too. In the home of the future,
say, I probably would like to have power/network for little sensors, etc, where
you already have a gratuitous digital controller now, and then some. Do these
things need to have gig-e speeds? Probably not... for a lot even Bluetooth speeds
are probably fine. But they do want to be really small and really inexpensive.

(Yes, I know about zigbee, but there's room for a variety of solutions depending
on the situation.)

Mike

26

I fully agree. I think the ethernet connector is pretty much the best and most useful one out there. Anything can be improved, however both from an admin and a user's perspective I can't find anything that works better, easier and is as sturdy.

Regards,
Jeroen

27

I think that you might be describing the DIX connector retaining clamp.

Dave Edelman

28

Having (once) tapped thicknet, done a lot of thinnet termination and
cable cut debugging, and then used hubs and switches in 10BT and
onwards...

Having had one main standard (RJ45) has been a huge benefit to
advancing the state of networking to where we are today. But it is
probably worth questioning if that's true going forwards.

Laptops and Rasberry PI devices and some other device types define a
"light" category, where positive retention and self-cable-termination
are probably not net positives. Device side space and interconnect
insert/remove cycles (along with sufficiently stiff connection
retention, but not necessarily mechanical) would be prime drivers for
this class.

For some users, even more positive than RJ45 is warranted. I at times
work in and have a number of friends working in various aerospace and
rocketry areas, and RJ45's have been widely known to come loose under
acceleration. Those people use more positive connctors (M12, other
IP67, etc) for the most part. Those other standards exist already,
though it's not unified down to one right answer yet.

For datacenters, servers, most desktops, etc., I don't know that
there's a good case for change. RJ45 is not broke for those users.

The comment upthread a bit about a 2-wire / 1 pair spec, interoperable
with 4-wire / 2 pair switches, with a RJ45 at one end and a device
connector at the other, makes sense to me. Most of the "light
connector" users would not need the full bandwidth. Even if this
turns out to not be easy enough to do, a 4-wire mini connector of some
sort is not that big of a deal. Whether that's a micro-insert, a
magnetic-attached, what details... I see good arguments for magnetic
attach, but it's harder to make them small. I see good arguments for
small, but those will be mechanical and less positively retained.

I don't know that the discussion is a NANOG-centric one from here on
in, but it's good to have raised the idea.

29

Then run RS-422 or RS-485 over a single twisted pair. You don't even need a connector – you can solder directly to the PCB.

--lyndon

30

I found that a spliced toothpick does wonders to prevent that. :wink:

31

I'm shocked there hasn't been a whisper of amphenol. As an rf guy, I vote all connectors move to sma or bnc. I can then justify the cost of a Walmart 10 foot cable for 25 dollars.. And if we gold plate them, we can charge a premium. :wink:

32

I was looking at a Raspberry Pi board and was struck with how large the ethernet
connector is in comparison to the board as a whole. It strikes me: ethernet
connectors haven't changed that I'm aware in pretty much 25 years. Every other
cable has changed several times in that time frame. I imaging that if anybody
cared, ethernet cables could be many times smaller. Looking at wiring closets,
etc, it seems like it might be a big win for density too.

I've you've ever seen a truly 'dense' wiring closet, they are plenty dense already - dense enough that unplugging a single patch cable in a rack jammed full of switches is already a bit of a chore.

So why, oh why, nanog the omniscient do we still use rj45's?

Inertia, for one thing. By that, I mean:
1. There hasn't been any real incentive to make the connectors smaller.
2. The installed base of copper Ethernet ports dwarfs pretty much anything except maybe POTS lines, and even there, different countries sometimes adopted their own standards. The costs of having to make physical changes to even a small portion of the installed cable plant would be unjustifiably prohibitive.

There could also be some valid technical reasons:
1. The conductors really can't get any thinner. In fact, with Cat6A, they're somewhat thicker than Cat5E.
2. I would also think that the conductors/pins really can't get much closer together inside the connector shell, without cross-talk becoming more of a problem. I don't have any technical data to back this up at the moment, but it seems reasonable.
3. If assertions 1 and 2 are true, then the cable really can't get any thinner either. Again, if you look at Cat6A cable (especially shielded Cat6A), it is significantly thicker than Cat5E.

jms

33

There could also be some valid technical reasons:
1. The conductors really can't get any thinner. In fact, with Cat6A,
they're somewhat thicker than Cat5E.
2. I would also think that the conductors/pins really can't get much
closer together inside the connector shell, without cross-talk becoming
more of a problem. I don't have any technical data to back this up at
the moment, but it seems reasonable.
3. If assertions 1 and 2 are true, then the cable really can't get any
thinner either. Again, if you look at Cat6A cable (especially shielded
Cat6A), it is significantly thicker than Cat5E.

I'll chime in here. With POTS, where essentially each "circuit" is identical in capacity and usage type, the only way to improve density is via the physical media -- and even then, you are still limited by conductor sizes.

With Ethernet, you've seen an evolution from 10MB/s to 10Gb/s. This begs the question of what density you need, and against uh, say, 1000x improvement in capacity, what meaningful change could you make in terms of connector density? Even 10:1 is meaningless noise against a speed improvement at the circuit layer.

Lots of Ethernet is still run identically to the way POTS lines are run. Large cable pulls back to central wiring closets. This is part of the problem.

If one chose to adopt a model where connections are multiplexed/aggregated closer to their source and the aggregation brings with it higher signalling speeds --- [Think top-of-rack switching vs end-of-row switching]. I'm not saying its useful for everyone, but the idea is that if density were your issue, there are much better physical ways to manage the data requirements than the POTS model.

In our office spaces (albeit in data center buildings) we have individual rooms with 24/48 port ethernet switches dedicated to the room. These uplink via a redundant pair of fiber. This represents lots of copper not making it out to the end-of-hall wiring closet which is now just a passive WDM fiber aggregation point. [Consummate savings in copper, weight, complexity, and labor -- at no significantly higher hardware failure risk].

Fiber has solved the density problem in a way that copper hasn't and this may be in part to reduced concerns about cross-talk and thinner media.

So with so many options to reduce the amount of copper you need, and the use of fiber to move large amounts of connectivity much longer distances and at higher speeds, why would you still want to implement a wiring closet with 2000 RJ-45s anymore -- and if you have the justification, what's another 5 square feet to make it happen against the costs you're already incurring?

DJ

34

Really, it will remain that way until the bandwidth needs from the
desktop begin to push the GE threshold. Until then, why bother
changing anything? When that does happen, it'll pretty well deal with
itself.

At which point the 8P8C connectors on desktops and laptops changes from RJ45 to
SFP+ cage with LC connector, or direct-attach SFP+ between
laptop and "active" fabric extender in the nearby wall jack; fed
by fiber, with 10G-SR optical...

Because the copper spec for >1gig was 10GBase-CX4; much heavier than Cat5.
And there won't be much tolerance for the copper 15 meter distance
limit in any case.

35

Something optical, like a >10 GBit/s SR version of TOSLINK
would be nice.

36

Good luck with that! :slight_smile:

Referring back to the original question and the reference to Raspberry Pi...

The latest HDMI has Ethernet capability and the connector is already on the
Pi, so there's a possible (future) solution that would work for all manner
of consumer applications - even ones that don't need video or audio - just
use the network capability of HDMI.

Aled

37

From: Warren Bailey [mailto:wbailey@satelliteintelligencegroup.com]

I'm shocked there hasn't been a whisper of amphenol. As an rf guy, I
vote all connectors move to sma or bnc. I can then justify the cost of
a Walmart 10 foot cable for 25 dollars.. And if we gold plate them, we
can charge a premium. :wink:

Let's just use MTC thermocouple connectors everywhere and be done with it.

Jamie

38

Are you talking about the "N" connectors with those 802.3 transceiver cables, BNC connectors (10Base5), or an Type RJ45 (10Base-T) telco style connector?

I couldn't find anyone selling multi-step thicknet strippers in the late 1980s, so I had to use a Xacto knife to prepare thicknet cable and then crimp about 20 N connectors. Data General donated 8 workstations and CAD circuit-design software to our University. The workstations used N-style transceivers instead of those with vampire taps.

What a nightmare! )-;

matthew black
california state university, long beach

39

http://www.blackbox.com/Store/Detail.aspx/Ethernet-Transceiver-Cable-Office-Environment-PVC-IEEE-802-3-Right-Angle-Connector-3-ft-0-9-m/LCN216Ă0003

Only $55.95 for a 3-foot transceiver cable. What was more surprising is that Black Box is still around.

matthew black
california state university, long beach

40

Some of us still have a stock of legacy gear and cables - things like v35 cables for connecting to CSU/DSUs, and even the occasional AUI hub. :slight_smile:

You wouldn't believe how much people will pay for legacy computer gear when they need it to keep their business going.