Disappointing Gigabits

So, my fiber provider started offering 25Gb connections—yes, that’s twenty five gigabits—for no additional cost. How could I resist?

Setup

It needed a router change, and different fibre optics (SFP+) module; apparently the faster connection is over a different wavelength of light. And then, nothing worked.

Given that I was working from home at the time this quickly became an urgent problem, since the slower connection had been switched off to provide the new one.

After much experimenting I discovered that it was a problem with the port settings on the router; turning off speed negotiation and some other arbitrary setting I can’t remember were enough to fix it. Mostly; more on that later.

Use

Then I hit a different problem. It turned out that none of my devices could actually use anything faster than a 1Gb connection. My main device for work was a Chromebox, so there was no way to swap in a new network card.

I tried to get a 5Gb USB adapter working, and failed; I think my Ethernet SPFs do not support 5Gb, only 1Gb or 10Gb.

Eventually I gave up. I suppose it’s technically possible to use more than 1Gb of the upstream connection, if multiple devices are connected via 1Gb Ethernet and sending data simultaneously. But there comes another problem: what can you actually use that bandwidth for?

The only service I’ve found that seems to reliably support relevant speeds is Steam, for slightly faster game downloads every week or three. I suppose BitTorrent might under some circumstances, but I don’t use it much these days.

We seem to have reached a point where the speed exceeds the need; so I now chuckle knowingly to myself whenever I see an advert for the “fastest connection in the land” that nobody will ever saturate.

Only Mostly Working

I then hit the most infuriating problem: intermittent outages. The connection would freeze completely for 30s, or thereabouts, multiple times per day. I checked every setting, tried every variation; eventually I gave in and called tech support. They had no ideas, or at least nothing that worked.

I switched devices and settings enough to convince myself that the problem could not possibly be at my end.

After a day or two, getting quite desperate by this point, I wrote a script to log when the outages happened, to look for any patterns. And to my astonishment I discovered that the outages happened exactly every 1000 seconds. This information was enough for tech support to escalate to their field techs, who started to dig.

Simultaneously with that I thought of a test: I turned off and unplugged everything for a while, then set up again and restarted logging. The logs showed that the 1000s cadence was uninterrupted, proving conclusively that the problem was not at my end.

That turned out to have been unnecessary, as anyway my next chat to tech support was the last: their field tech had determined that a router belonging to another customer was sending bad requests every 1000s, causing their equipment to drop my DHCP session.

That does not sound to me like a thing that should be possible, but, no matter; it suggested to them a simple pragmatic solution: to create a static route pinned to my router MAC address. This done, the problem was solved.

Now all I have to do is remember to call tech support again if I ever change router, or it’s not going to work at all.

Conclusion

Those extra gigabits were, sadly, not at all worth the effort. At least, not yet; I suppose we are now 25x future proof!

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