Posts by Stormgren@obsidianmoon.com
(DIR) Post #B4CU6dAbZGyzLbTlse by Stormgren@obsidianmoon.com
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@MLE_online @azonenberg So you're saying I'm flying out to LA next week just in time for a biblical event?
(DIR) Post #B4CU6dcbt9NskSa8X2 by Stormgren@obsidianmoon.com
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@MLE_online @azonenberg Can't be worse than all the trade show attendees I'll be surrounded by. 😂
(DIR) Post #B4CUd5vICTp7n2nSzI by Stormgren@obsidianmoon.com
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@azonenberg @MLE_online OFC is next week, attending the conference and then the trade show for most of the week, because the bits must flow!
(DIR) Post #B4CVEQf23pLiozzfXs by Stormgren@obsidianmoon.com
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@azonenberg @MLE_online I've been offering for years to some of the vendors that if they don't want to pay to ship some of that stuff home, I'll gladly take it off their hands. Keysight never seems to be interested for some reason.Given Emily is now finding these specimens, I'm wondering what the exchange rate for one fiber optic cable is in giant LA grasshoppers.
(DIR) Post #B5n0BCS4ZTMPxEweEC by Stormgren@obsidianmoon.com
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@jpm @azonenberg @whitequark I would tend to agree about the buffering, sometimes that throws timing of packet flows off a bit. I've found that 4x10G lanes from a switch to a QSFP vs 4x25G can be treated very differently. I've oft suspected that the chip and SERDES optimization on a lot of platforms is oriented for 100G and 40G is there just for backward compatibility but isn't performant.At the same time.however, I wouldn't be surprised if it really just did come down to the NIC. The 710 series isn't a great card in general, and I actually had to go back to the 520-DA2s to get things like hardware timestamping back and the 520 also handled VFIO a heck of a lot better. The second I get out of home improvement hell here and can scrape up some cash to go ConnectX of some kind, I am 100% going for it (along with the required switching upgrade, I'm 10G only for now).
(DIR) Post #B6QOpPyvf5axZ5ScyG by Stormgren@obsidianmoon.com
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I don't think a media converter can't get any more simple than this...Nominally 1G and below convertible, I tested it at 10g over the weekend via iperf3 and generic 10g plugs seem to be okay with it. No active cooling so higher-power plugs might be an issue.Pretty sure the LM358 is used as a link detector of some kind by monitoring the LOS pin and lighting the port LED accordingly.(And yes, I actually need it that simple for some of the current nutty stuff I'm working on at work. Retiming won't be my friend here.)
(DIR) Post #B6QQ6VgjnWum8mfLSi by Stormgren@obsidianmoon.com
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@azonenberg I was also thinking that those coupling caps were slightly suspicious. I wonder if it's to break up the trace lengths more than be a blocking capacitor between the plugs?As for your custom breakout, that sounds incredibly handy! I've considered designing something like that myself, but just don't have enough spare time right now. I've been looking for SFP breakout boards for another experiment we're looking to run, and they're either crazy expensive or kinda unobtanium. Best option I've found for a somewhat reasonable price is the Osmocom experimenter boards with the built-in differential drivers, as I need to inject arbitrary single-ended signals into a SFP driver and also be able to read the I2C and other pins as well.If you have any thoughts on breakout board sources, designs or whatnot, I'd really appreciate hearing them.
(DIR) Post #B6QRJKivyW5HqyN6RM by Stormgren@obsidianmoon.com
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@azonenberg That is a heck of a serious board-edge SMA connector! I tend to only use board-edge SMA with short chassis-mounted extension cables for the reason you mentioned, the fatigue tends to kill the solder joint.Back to the decoupling capacitors, I'm also wondering if they are present to account for things like DAC cables that mount zero caps anywhere on them, because those do exist and they're super annoying to work with.
(DIR) Post #B6QRbxaiComvbwPLTk by Stormgren@obsidianmoon.com
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@azonenberg That actually might be somewhat relevant to my work, so thank you!Also, it just occurred to me that for a quick proof of concept while I wait on my osmocom boards is that I could always attach some of these LVDS drivers around here (assuming i can find where i stashed the things) to a cut-up DAC cable to do a quick proof of concept of a thing we want to try.Nutty, but hey, needs must, right? :)
(DIR) Post #B6QSVGiOnxOAqlNP1c by Stormgren@obsidianmoon.com
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@azonenberg Oh, I have my copy of 8431 right here, and yes, you are correct, they should have DC blocks on both TX and RX. (Per section 3.4)That being said I have done teardowns on some suspect DACs and the traces weren't even jumpered over where there should be a capacitor, the cap wasn't even there! Wouldn't surprise me if there were some optical units out there that did the same thing for some reason. Initial symptoms didn't present on that issue until someone jumpered the NICs between boxes in adjacent rack cabinets and the NIC crashed in one or both of the boxes.Connection in the same rack didn't trigger the issue in shorter cables but doing a cabinet-cabinet DAC run would. My guess is potential differences based on different power circuits or something, but the cabinets were at least bonded together, so IDK. The solution was to NOT violate our SOP of never doing cabinet-cabinet DAC connections and do something optically, and then rip-and-replace the crap cables.
(DIR) Post #B6QSeO4wnQ8eIJGt72 by Stormgren@obsidianmoon.com
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@azonenberg I feel like the Samtec connector's mounting posts are almost structural, like you could hold the board up by the thing if you did it as through-hole somehow. 😁
(DIR) Post #B6QWhC9C0t4XyUqqbw by Stormgren@obsidianmoon.com
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@azonenberg It's a professional hazard. I won't claim to have them memorized, but I keep a few around so I can have arguments with product developers when I have to convince them they're wrong about something (and they're often wrong).That being said, I was just saying something similar before you posted. I never know what sort of crazy discussion I'm going to get into here when I mention something esoteric.
(DIR) Post #B6TGomD9JNsq3kAunI by Stormgren@obsidianmoon.com
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@azonenberg @penguin42 Oh don't think I haven't considered bolting a LVDS driver to a morse key to make that a thing that happens! :)
(DIR) Post #B6jm8xSFtzapC5SAfw by Stormgren@obsidianmoon.com
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@azonenberg @jpm I think those are FSOS, which in that case "crypto key generate (rsa or dsa)" should be the start of that command
(DIR) Post #B6plvvUB4qzeGrtjoO by Stormgren@obsidianmoon.com
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@MLE_online That is absolutely wonderful.I love the fact that you marked B-C-E on the clay for the transistor connection.Curious though, is that some sort of dual transistor package that's running the whole thing? Can't say I recognize it.
(DIR) Post #B9P8rb6dmZeXCRSG4u by Stormgren@obsidianmoon.com
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@ariadne I think I have more non-Docker installs of Alpine right now than Docker containers of Alpine.
(DIR) Post #B9kXoccdsgIKQ0g1dQ by Stormgren@obsidianmoon.com
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@ariadne If it wasn't for some interesting people I sometimes converse with over there, I'd just defed that damn site.