Old problem still present on 11-ALPHA1 - Pi2

[Russell Haley]

On Mon, Jul 11, 2016 at 9:15 AM, Karl Denninger <karl at denninger.net> wrote:
> I have two PI2s on the same switch here doing quite-different things.
>
> One never shows network problems.  The other one does this:
>
> ....
>
> ukphy0:  none, 10baseT, 10baseT-FDX, 100baseTX, 100baseTX-FDX, auto
> ue0: <USB Ethernet> on smsc0
> ue0: Ethernet address: b8:27:eb:08:12:1c
> ugen0.4: <Inateck> at usbus0
> umass0: <Inateck product 0x5136, class 0/0, rev 2.10/0.01, addr 4> on usbus0
> umass0:  SCSI over Bulk-Only; quirks = 0x0100
> umass0:0:0: Attached to scbus0
> da0 at umass-sim0 bus 0 scbus0 target 0 lun 0
> da0: <Inateck  0> Fixed Direct Access SPC-4 SCSI device
> da0: Serial Number 00000000000000000000
> da0: 40.000MB/s transfers
> da0: 476940MB (976773168 512 byte sectors)
> da0: quirks=0x2<NO_6_BYTE>
> random: unblocking device.
> smsc0: chip 0xec00, rev. 0002
> ue0: link state changed to DOWN
> ue0: link state changed to UP
> ue0.2: link state changed to UP
> ue0.3: link state changed to UP
> ue0: link state changed to DOWN
> ue0.2: link state changed to DOWN
> ue0.3: link state changed to DOWN
> ue0: link state changed to UP
> ue0.2: link state changed to UP
> ue0.3: link state changed to UP
> ue0: link state changed to DOWN
> ue0.2: link state changed to DOWN
> ue0.3: link state changed to DOWN
> ue0: link state changed to UP
> ue0.2: link state changed to UP
> ue0.3: link state changed to UP
> ue0: link state changed to DOWN
> ue0.2: link state changed to DOWN
> ue0.3: link state changed to DOWN
> ue0: link state changed to UP
> ue0.2: link state changed to UP
> ue0.3: link state changed to UP

It's interesting that it flapped down (and then back up) three times
and you have three interfaces. Does it do that consistently? Does it
do it twice if there is only two interface (base plus a vlan)?

Can you share the interface configuration source? Have you checked
your system resources close to an expected flap to see if there is
ballooning resources somewhere? Brendan Gregg has some fantastic
tracing resources. Here are a couple of my favorites (not that I
profess to know anything about dtrace...)

http://www.brendangregg.com/USEmethod/use-freebsd.html
http://www.brendangregg.com/dtrace.html
https://forums.freebsd.org/threads/48802/

Russ

> Every now and then (every hour or so) the interface flaps.  If I plug a
> USB interface in and use two network cords I *still* get the flapping.
> This unit has very low (but non-zero) traffic on the network, while the
> other actually has *more* traffic on the network yet is completely
> stable.  Since both are plugged into the same physical switch I doubt
> the switch itself or its firmware is involved in this.
>
> The only difference I can see is that the one that flaps is using
> vlans.  Specifically, that machine is the network's dhcp server, and it
> is on three different vlans (untagged and two tagged) so it can provide
> addresses (and DNS services via unbound) to those VLAN interfaces.
>
> This appears to be somehow linked to the ue interface driver, because
> another machine (Intel based) that is also on multiple vLANs via the em
> driver does *not* flap.
>
> I don't know if this is actually arm related or not; it might not be if
> Intel machines also use the "ue" driver, but it's very consistent on the
> PI2 if I want to use vlan tags whether I have one or two interfaces (the
> second via a USB adapter of course) in use or not.
>
> Other than the flapping the box appears to run fine; the flaps do,
> however, sometimes stop reporting from the snmpd daemon so I have had to
> stick a cron job out there to restart that on a schedule to prevent it
> from interrupting reporting to my traffic management tools.  Whether the
> two are related is not known with certainty (but I suspect it is.)
>
> --
> Karl Denninger
> karl at denninger.net <mailto:karl at denninger.net>
> /The Market Ticker/
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