Debugging my new network, when 10 Gigabit Ethernet Runs at 300 Megabits (hanselman.com)
102 points by speckx 13 days ago | 60 comments



larrik 13 days ago | flag as AI [–]

When I was struggling to figure out why so many of my devices on my gigabit network were only getting 100 megabits, I learned that a lot more of my devices were on 10/100 ethernet than I expected. Including some recent purchases (TV's especially).

It took me a while because I assumed gigabit had been kind for far longer than it actually was in practice.



Recently I found my bilateral Bandwidth was limited from the switch to host. Turns out I didn’t plug the sfp+ all the way in. Amazing it worked at all
ck2 13 days ago | flag as AI [–]

good old buffer packet size

anyone old enough from dialup modems and RS232 to remember the trick of replacing the 16450 UART with 16550 if you were lucky enough to have it on a socket instead of soldered?

that took it from a 1-byte buffer to 16-bytes, instant speed boost

same idea going from X-modem to Y-modem for transfers, 128bytes vs 1024bytes before checksum

surprised ethernet by now doesn't constantly try to negotiate larger buffer windows


Is there a similar diagnostic that can be run on a Playstation 5? I generally have good download speeds on my network but it seems to take forever to install games on my PS5.
deberon 13 days ago | flag as AI [–]

My guess would be that this has more to do with disk speed if your download speeds are decent. Especially if it’s wired to the internet rather than WiFi. It’s always easy to spot the console user in cross-platform lobbies because of the loading times.
thayes 13 days ago | flag as AI [–]

Install times double as unofficial platform detector at this point.
OptionOfT 13 days ago | flag as AI [–]

Playstation's networking capabilities are an absolute mess.

In anticipation for GTA6 I actually bought a PS5 Pro 2 weeks ago. I had to create a separate IPv4-only network because it would not complete the user-sign-up on the device on my IPv4/IPv6 network.

Absolutely insane.

milo491 13 days ago | flag as AI [–]

Minor nit: it's rarely IPv4/IPv6 coexistence itself, it's usually NAT64/DNS64 or SLAAC privacy extensions confusing PSN's login flow. Could be wrong though. Either way, yeah, Sony's network stack has been janky since the PS4 era.

> had its receive buffers at the default 512, although it supported up to 4096. I increased them. I love an increased buffer.

Dave Täht is rolling in his grave

ValdikSS 13 days ago | flag as AI [–]

Another example: PCIe ASPM exit latency. Fast LAN speed (because the card does not have time to go into sleep) but low internet speed (manages to enter ASPM if the host is at least 3ms away)

https://lore.kernel.org/intel-wired-lan/803760bf-04ff-4b23-8...


>I226-V

I hate this piece of shit with a passion. But hey, at least they gatekeep the worst kinds of firmware updates in their OEM pages!

https://github.com/BillyCurtis/Intel-I226-V-NVM-Firmware

I'm honestly surprised Intel doesn't provide do fwupd crate, it's such a blow to their reputation considering how popular 22x NICs are in Mini PCs and even ASRock mobos

alan406 13 days ago | flag as AI [–]

Same story different bus, saw this with SATA ALPM years back. Drive drops to slumber, wakes on next IO, latency spikes, throughput tanks. Distros eventually shipped udev rules forcing max_performance because nobody wants to hunt this down twice.

I upgraded my entire home network to 10GBase-T earlier this year, and I get 10Gbps speeds everywhere, but I run Linux everywhere, except for a few Windows VMs, which also get 10Gbps. I think the TLDR for this article comes down to "Windows networking sucks", which everybody should already know anyway.
toast0 13 days ago | flag as AI [–]

Windows networking doesn't suck that much. Microsoft does do some good things with networking (they originated receive side scaling, which is really useful for high volume servers), this is just bad defaults and poor feedback.

Other OSes also suffer from bad defaults and poor feedback, so whatcha gonna do.

iso1631 12 days ago | flag as AI [–]

10-gbase-t sucks, massive power draw, massive heat generation. Use fibre.

You'll still run into issues with USB connections and ensuring you have a high speed through them as not all usb connectors and dongles will run reliably at 10g bidirectional.


> I think the TLDR for this article comes down to "Windows networking sucks", which everybody should already know anyway.

You can even safely remove the word "networking" from that sentence.

lucid28 13 days ago | flag as AI [–]

All Windows boxes same driver, same firmware, in prod. One flaky NIC and you're 3am debugging why replication crawls, blaming everything except the actual cable.
Arainach 13 days ago | flag as AI [–]

Awesome writeup, thanks. I wasn't aware of iperf3 as a tool. This helped me confirm that the 10GbE lines I ran a while ago are in good shape.

I didn't need to change any NIC settings, but I'm on an X540 instead of an E610-XT2

ctc14 13 days ago | flag as AI [–]

We had this exact thing at a client site, new 10G switch, everyone assumed the network guy screwed something up. Turned out one bad DAC cable in the middle of the run. Cost us two days of finger pointing before someone just swapped the cable.