Comment by gerdesj | Hacker News Reader

Comment by gerdesj | Hacker News Reader

"Network switches are simple devices, packets go in, packets go out. Luckily people have figured out how to make it complicated instead and invented managed switches."

Expensive switches involve some pretty fancy ASICs. For example I have a pair of fairly elderly Dell OS9 switches with 48 x 10Gb/s ports and four x 40Gb/s QSFP+ fibre ports. These are "old skool" stacked jobbies. Each switch can shuffle up to 1.28Tb/s (1). That's quite a lot. You can get those for £1800 including VAT (2) these days and they will last nearly forever.

I love to see efforts like this but do bear in mind that say Netgear will do a eight port 1Gb switch with Power over Ethernet on all ports for about £125.

If you cost your time at somewhere between £20-50 per hour when evaluating whether a project is financially viable, then an off the shelf box might be indicated. However, if the actual purpose is the project itself then sod the price!

(1) https://i.dell.com/sites/doccontent/shared-content/data-shee... (2) https://www.etb-tech.com/dell-force10-s4820t-10gbe-switch-os...

I worked with one of these ASICs, from Broadcom. Not 40, but something like 4x10+24x1Gbps + PCIe to CPU. The ASIC cost as much as you would expect (I don't know the actual number - a couple hundred bucks?). The software interface to it was very poorly documented, and was a library that supported all Broadcom switch ASICs, so was a few hundred megabytes .a file and was full of functions that would just return "not supported on this device" errors, which you wouldn't know until you tried it.

Not Broadcom, but Microchip has list prices straight on their website (how refreshing!), and yeah few hundred bucks sounds about right; for example this random 128Gbps switch chip is about $120 in single quantities, $80 in volume

https://www.microchip.com/en-us/product/vsc7552#purchase-fro...

It feels bit bonkers that a actual switch based on that probably costs thousands.

The software side is crap as usual. They sell their Linux-based package at $75000, with maintenance (basically updates) at $17500.

So even though the chip is cheap, you need to burn six figures to do anything with them :(

Their Sparx-5 line is supported by stock upstream Linux switchdev.

Intrigued by that, I went looking. First commit of support was 2019, for Linux5.2. Yet, 5 years later, there is not one example (that i could find) of OpenWrt running on these Chips. If the platform/FW/BSP package were any good, I'd expect there to be chat about it in the forums, and/or attempts to port to such devices from SMBStaX (The Microchip BSP Linux dist).

I suspect it's not worth the effort for most people. People who want to DIY a switch are likely content to brute force it with a decent cpu, multiport network cards, and lots of PCIe lanes. While others will be happy with a used enterprise OEM unit.

Does make me wonder what asics Microtik is using under the hood though...

A lot of them are just networking SoCs with built in switching fabrics or the lower end ones have the low end router SoC from various manufacturers.

Mikrotik is one of the few brands that actually list this in the spec sheets.

You are right, the situation is better that what I thought, the commercial smbstax SDK might not be absolutely required.

They even have some BSP stuff freely available which is really positive sign. https://github.com/microchip-ung/bsp-doc

This would be such an enticing project to jump into, there are just enough bits to make it seem doable, even if the realist in me knows its not really feasible.

That's a very cheap price for enterprise layer 3 switching chip. Thanks for the info, how this switch chip has escaped me is very perplexing.

Can you elaborate on their Linux-based package, is the package critical for the development and using the chip with embedded Linux. Can we just use it as switching fabric and use Intel CPU for example N100 as the main controller running Linux?

The sibling comment also mentioned that Sparx-5 line is supported by stock upstream Linux switchdev, and this the same chip as in your link.

Ignorance is bliss.

Reply on news.ycombinator.com