That is cool. I use a gps NTP server on my home network and live with sub-millisecond time sync. I’d go PTP but the equipment is a bit too expensive if the only value add is better time sync and I don’t need additional bandwidth. Prices coming down would be nice.
What's expensive? PTP is widely supported on commodity hardware these days. I think most Intel NICs support it, quite a few Realtek and a lot of embedded stuff, down to even MCUs like STM32.
Even if you want a NIC with a stable oscillator or GPS inputs to act as a grandmaster, you can buy an E810 with the necessary hardware from eBay etc. for a few hundred or DIY something yourself much cheaper.
I have an Intel NIC (an Intel I211 using ixgbe) and a Broadcom NIC (BCM5719 using tg3) that claim to support PTP. I'm using the 802.11as profile on my LAN. These NICs are hooked up to Mikrotik CRS326-24G-2S+'s that also claim to support PTP.
Despite my neighbor switches reliably emitting Announce packets every second [0] the Intel NIC will -every few hours- fail to pass along three of those in a row to ptp4l, causing it to switch grandmaster mode for a few seconds before it recovers. The Broadcom NIC does this once or twice a day. These failures happen on both systems, regardless of system load. I've tried fiddling with a whole bunch of ptp4l settings to relax delivery timeouts, and it doesn't seem to help.
So, yeah, just because something claims to support PTP doesn't mean that it'll actually work well.
[0] I know this because packet capture during a couple of the incidents confirms this.
Yes. I'm aware. Perhaps I'm more stupid about this topic than normal, but it looks to me like the NICs I have do (NIC names have been changed for clarity, but all other output is untouched):
$ ethtool -T intel-nic
Time stamping parameters for intel-nic:
Capabilities:
hardware-transmit
software-transmit
hardware-receive
software-receive
software-system-clock
hardware-raw-clock
Hardware timestamp provider index: 0
Hardware timestamp provider qualifier: Precise (IEEE 1588 quality)
Hardware timestamp source: MAC
Hardware Transmit Timestamp Modes:
off
on
Hardware Receive Filter Modes:
none
all
$ ethtool -T brcm-nic
Time stamping parameters for brcm-nic:
Capabilities:
hardware-transmit
software-transmit
hardware-receive
software-receive
software-system-clock
hardware-raw-clock
Hardware timestamp provider index: 0
Hardware timestamp provider qualifier: Precise (IEEE 1588 quality)
Hardware timestamp source: MAC
Hardware Transmit Timestamp Modes:
off
on
Hardware Receive Filter Modes:
none
ptpv1-l4-event
ptpv2-l4-event
ptpv2-l2-event
Intel's drivers are notoriously annoying as the parent of the parent comment suggests. It seems to be a mix of hardware bugs and a driver that doesn't properly account for them. I know many who've moved to ASIX, Mellanox, and other chipsets just because they don't get weird behaviors or two edges per pulse without hacking the driver.
> It seems to be a mix of hardware bugs and a driver that doesn't properly account for them.
~~yaaaaay~~
Also, who the heck knows if my switches are behaving correctly? I may be dealing with a system with multiple failing components.
I'd never considered Mellanox hardware... I'd always thought of them as "super expensive datacenter hardware", but non-Infiniband cards I can see on Newegg aren't entirely-unreasonably priced. (TBD if I can find a PCI-E 2.0 1x card, though). I'd not heard of ASIX, and they have a card that would fit in my slot, but -sadly- no in-tree driver. It looks like the only in-tree driver is for a 100mbit card... the AX88796C.
Anyway, thanks for the advice/info and the mention of more-reliable manufacturers.
Switches that properly support PTP are expensive, at least for now.
You can achieve microsecond accuracy with a lot of non-timing-specific networking hardware, but it's around as good as you get with modern NTP...
To get sub-microsecond, you need hardware that supports transparent/boundary clock and doesn't just 'say' it does, but actually does (vendors have stamped PTP support on things that definitely don't account for time correctly internally!).
I use it for home router, my laptop, several vms for various services, and on one vps I keep around should I need to quickly set something up. I keep a proxmox server for anything I can’t or won’t run on OpenBSD.
It is amazing to me that people still answer their phone. If it isn’t my wife or kids then my phone has a silent ringtone. If your voice mail doesn’t successfully transcribe to text then I delete it without listening. I check my postal mail since mail fraud is the only thing still taken seriously by anyone.
Is mail fraud really taken seriously? after I bought my house I got dozens of letters every few days that appeared (or tried to appear) from my lender warning of "FINAL NOTICE call this number about your mortgage!!!!!". The phenomenon is apparently so common and well known that my realtor, the seller's realtor, and my lender ALL warned me about these letters.
I feel like it should be easy for the postal inspectors or to go after these, if they cared. Just gather up some of these letters from someone who just bought a house (seems to be public record when someone buys a house, that's how the scammers know when to target someone). Then just call the number in the letter, trace the call and arrest whoever is there.
This workaround only applies to kernels with the impacted code compiled as a module. RHEL, Fedora, and Gentoo (we use a modified Fedora config) all are configured to build this in directly. Without a patch or config change (as Sam from Gentoo was alluding to), those distributions remain vulnerable.
For compiled-in kernels you can also work around it without rebooting via apparmor, seccomp or SELinux at the least, there may be eBPF or other methods too.
That doesn't solve anything when the fraudster is filing a fake return. They are under no obligation to include all of your carefully chosen income and deductions that get you to $1000 owed.
What? In order to get a refund, that means you have to overpaid what you owe. It's pretty simple. If you are not putting in enough, the fraudster cannot get a refund as you still owe. Like, where is the break down? They would have to know how much you have paid, and then file so many deductions that it'd probably trigger an audit. If you file that many audits not with an account signing off of them, I could only imagine that would trigger an audit as well. Then again, the IRS has been beaten so badly that they barely have enough employees to function.
The fraudster claims that you installed energy efficient home improvements that qualify for the max $3,200 tax credit. Now that $1,000 in tax owed is a $2,200 refund. Maybe you get audited, but the IRS is certainly not auditing everyone who claims a tax credit.
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