Re: 60+% ping packet loss on Pi3 under -current and stable-13

On 2022-Apr-29, at 19:12, bob prohaska <fbsd@www.zefox.net> wrote:

> Since about December of 2021 I've been noticing problems with
> wired network connectivity on a pair of raspberry pi 3 machines
> using wired network connections. One runs stable-13.1, the other
> runs -current, both are up to date as of a few days ago.

Compared to your later notes about 192.168.1.n style use,
are any of the above that way? Or are the all well-analogous
to the "on the public network" context mentioned later?

> Essentially both machines fail to respond to inbound network
> connections via ssh or ping after reboot. If I get on the 
> serial console and start an outbound ping to anywhere, both
> machines respond to incoming pings with about a 65% packet
> loss. Ssh connections are answered with delays of zero to
> perhaps thirty seconds. Once connected ssh is usable but
> erratic, with dropped characters, multi-second delays and
> disconnects after random intervals from minutes to hours.
> 
> There are five other Raspberry Pi's on the network. Three
> Pi2's run 12.3-stable, one Pi2 runs -current

RPi2 v1.2's used as aarch64? (So similar to RPi3*'s.)
RPi2 v1.1's (armv7)?

Which type of RPi3* variant? B? B+? Revision?

> and a Pi4 runs
> -current. All have no problems pinging one another and out
> of network, so there's nothing obviously wrong with the net.
> The network is not routed, but rather a block of eight
> addresses simply bridged from my ISP over DSL.
> 
> It's been found that an image of 13.1-RC4 behaves similarly
> on one Pi3 when on the public network but exhibits more normal
> ping response when moved to a 192.168.1.n private network. On
> the face of it, this seems significant, but I can't guess how.

Did you try a RPi4B on the public network, booted using the
same 13.1-RC4 microsd card you used in the RPi3* testing?
(Modern aarch64 RPi* images should boot either type of
aarch64 RPI*.)

If yes, what was the behavior like? Did it behave like the
RPi3*?

If no, it should be a good test for how specific the problem
is to the RPi3* vs. RPi*'s more generally.

Testing a EtherNet dongle known to use a different driver
could also be a form of cross check, if you happen to have
such available.

> I recall a post on one of the mailing lists about a bug that
> caused problems when packets arrived out-of-order via NAT, 
> but I'm using direct same-network pings and pinging through 
> NAT seems little-to-no worse.
> 
> I was hoping to upgrade my stable-12 machines to stable-13,
> but seeing this behavior gives me pause. If anyone can 
> suggest tests or experiments to figure out what's going on
> I'd be most grateful. I'm no programmer but can follow 
> simple instructions. If this sounds like a known bug(s)
> links to bugzilla would be of much interest.
> 
> Many thanks for reading, and any ideas! If some essential
> details have been omitted please indicate and I'll try to
> supply them. 
> 

My questions and suggestions are all not network-knowledge
specific. My background does not span the public network
related material, sorry.

(Some of this duplicates some off-list activity.)


===
Mark Millard
marklmi at yahoo.com