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Comment by adamcharnock | Hacker News Reader

That’s interesting. And I’m sure they have some very knowledgable people working for them who may(/will) know things I don’t.

That being said, it wouldn’t surprise me if they were pushing 17G of UDP on 100G transports. Probably with some pretty high-end/expensive network hardware with huge buffers. I.e you can do it if you’ve got the money, but I bet TCP would still have better raw throughput.

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Yep, 100G switches are common nowadays since the cost has come down so much, and you can easily carve a port to 4x10G, 4x25G, and 40G. In financial trading you tend to avoid switches with huge buffer as that comes to a huge cost in latency. For example, 2 megabytes of buffer is 1.68ms of latency on a 10G switch which is an eon in trading. Most opt for cut-through switches with shallow buffers measured in 100s of nanoseconds. If you want to get really crazy there are L1 switches that can do 5ns.

That is a really good point that I hadn’t considered. Presumably this comes at the risk of dropped packets if the upstream link becomes saturated? Does one just size the links accordingly to avoid that?

Basically yes, but the links themselves are controlled by the exchanges (and tied in to your general contact for market access).

In general UDP is not a problem in the space because of overprovisioning. Think "algorithms are for people who don't know how to buy more RAM", but with a finicial industry budget behind it.

Do the vendors actually convince anyone to buy those hubs rebranded as "ultra high performance 5ns L1 switches"?

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