Do all of the cheap eBay 32xQSFP28 SONiC switches have dodgy Atom C2000s?

[Scott Laird]

I’m considering buying a new switch or two for running SONiC. They’d be replacing a Gnodal 40GbE switch and a Juniper EX4500 10GbE switch. I need 20-ish QSFP ports and 20-ish SFP ports. Everything is 40/10 Gbps right now, and I don’t really *need* more bandwidth, but I’d rather buy 100/25 ports than 40/10 ports, just for future flexibility, assuming prices are ok.

Looking over the SONiC support list and eBay, it looks like there are mostly two classes of device to choose from right now if I’m trying to stay under $1k:

- Arista 7050s, with 32x40 ports and an old, slow CPU. But it’ll probably work for years, until SONiC grows too big for RAM/flash.
- Edge-Core / Acton switches with C2758 CPUs, in a few different port configurations including 32x100. Here’s one example AS7512-32X for $800.

Given the prices, I pretty much have to assume that the cheap Edge-Cores all have at least *potentially* dodgy CPUs, and once they die they’ll be useless and unrepairable, although it wouldn’t shock me to find that some of the devices have C2000 rev C0 or have a workaround in place. Has anyone actually bought any of these and found non-broken CPU revs? Or is there a better option out there that I’m missing?

 

[WANg]

I’m considering buying a new switch or two for running SONiC. They’d be replacing a Gnodal 40GbE switch and a Juniper EX4500 10GbE switch. I need 20-ish QSFP ports and 20-ish SFP ports. Everything is 40/10 Gbps right now, and I don’t really *need* more bandwidth, but I’d rather buy 100/25 ports than 40/10 ports, just for future flexibility, assuming prices are ok.

Looking over the SONiC support list and eBay, it looks like there are mostly two classes of device to choose from right now if I’m trying to stay under $1k:

- Arista 7050s, with 32x40 ports and an old, slow CPU. But it’ll probably work for years, until SONiC grows too big for RAM/flash.
- Edge-Core / Acton switches with C2758 CPUs, in a few different port configurations including 32x100. Here’s one example AS7512-32X for $800.

Given the prices, I pretty much have to assume that the cheap Edge-Cores all have at least *potentially* dodgy CPUs, and once they die they’ll be useless and unrepairable, although it wouldn’t shock me to find that some of the devices have C2000 rev C0 or have a workaround in place. Has anyone actually bought any of these and found non-broken CPU revs? Or is there a better option out there that I’m missing?

The Arista 7050s have 2 CPU types - the Athlon Neo x2 on the SX and early QX32, and GX420CA on the 40GbE QX32s series.
in general the GX420CA behaves like "half a C2758" (it's a quadcore and scores roughly half of the 8 core C2758 in CPUMarks scores) and double of the Athlon Neo x2, so I would not consider the QX32s to be "old and slow". One major plus is that their one RAM slot can take a 16GB DIMM, so at the very least they can have a bit more longevity than you might think.

 

[Scott Laird]

I ended up ordering a pair of Edge-Core switches. One has a Xeon-D, so I'm not too worried about it, and the other is a C2xxx. The DIY fix for the C2xxx is just adding a ~100 Ohm resistor across a couple pins that are *probably* exposed on a debug header somewhere. I figured I'd take the risk to get a 32x 100GbE switch for cheap.

 

[WANg]

I ended up ordering a pair of Edge-Core switches. One has a Xeon-D, so I'm not too worried about it, and the other is a C2xxx. The DIY fix for the C2xxx is just adding a ~100 Ohm resistor across a couple pins that are *probably* exposed on a debug header somewhere. I figured I'd take the risk to get a 32x 100GbE switch for cheap.

From what I understand, adding that resistor is not really a permanent fix as much as a band-aid - the LPC clock on the Atom C2xxx will eventually degrade until it stops working one day even with the resistor - it just merely reduces the impact on faulty silicon, so keep that in mind. The Xeon-D one is a good idea.