RPI 3B+ reporting carrier lost on ether connection

[Peter Collinson]

My new RPi 3B+ is reporting a dropped carrier on the ethernet connection.

Apr 2 15:37:31 tiny dhcpcd[423]: eth0: carrier acquired
Apr 2 15:37:32 tiny dhcpcd[423]: eth0: carrier lost
Apr 2 15:37:35 tiny dhcpcd[423]: eth0: carrier acquired
Apr 2 15:52:14 tiny dhcpcd[423]: eth0: carrier lost
Apr 2 15:52:17 tiny dhcpcd[423]: eth0: carrier acquired
Apr 2 16:11:59 tiny dhcpcd[423]: eth0: carrier lost
Apr 2 16:12:02 tiny dhcpcd[423]: eth0: carrier acquired
Apr 2 16:21:50 tiny dhcpcd[423]: eth0: carrier lost
Apr 2 16:21:53 tiny dhcpcd[423]: eth0: carrier acquired
Apr 2 16:25:29 tiny dhcpcd[423]: eth0: carrier lost
Apr 2 16:25:32 tiny dhcpcd[423]: eth0: carrier acquired

This is fairly frequent.

The system is running stretch - and has one mmc card, and two usb memory cards installed.
I've removed all the other connections to see if the power drain from the keyboard would affect things. It doesn't. I've also replaced the cable connecting the machine to the Netgear switch - it's now definitely a Cat 6 cable.

uname -a
Linux tiny 4.14.30-v7+ #1102 SMP Mon Mar 26 16:45:49 BST 2018 armv7l GNU/Linux

ifconfig

eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
        inet 10.10.10.16 netmask 255.255.255.0 broadcast 10.10.10.255
        inet6 fe80::9185:a5bb:87e3:26b3 prefixlen 64 scopeid 0x20<link>
        ether b8:27:eb:29:96:9c txqueuelen 1000 (Ethernet)
        RX packets 1619314 bytes 2315374529 (2.1 GiB)
        RX errors 0 dropped 1 overruns 0 frame 0
        TX packets 605709 bytes 585437555 (558.3 MiB)
        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
lo and unconfigured wlan0 is shown.

lshw
tiny
    description: ARMv7 Processor rev 4 (v7l)
    product: Raspberry Pi 3 Model B Plus Rev 1.3
    serial: 000000006b29969c
    width: 32 bits
    capabilities: smp
  *-core
       description: Motherboard
       physical id: 0
     *-cpu:0
          description: CPU
          product: cpu
          physical id: 0
          bus info: cpu@0
          size: 1400MHz
          capacity: 1400MHz
          capabilities: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 cpufreq
     *-cpu:1
          description: CPU
          product: cpu
          physical id: 1
          bus info: cpu@1
          size: 1400MHz
          capacity: 1400MHz
          capabilities: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 cpufreq
     *-cpu:2
          description: CPU
          product: cpu
          physical id: 2
          bus info: cpu@2
          size: 1400MHz
          capacity: 1400MHz
          capabilities: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 cpufreq
     *-cpu:3
          description: CPU
          product: cpu
          physical id: 3
          bus info: cpu@3
          size: 1400MHz
          capacity: 1400MHz
          capabilities: half thumb fastmult vfp edsp neon vfpv3 tls vfpv4 idiva idivt vfpd32 lpae evtstrm crc32 cpufreq
     *-memory
          description: System memory
          physical id: 4
          size: 927MiB
  *-usbhost
       product: DWC OTG Controller
       vendor: Linux 4.14.30-v7+ dwc_otg_hcd
       physical id: 1
       bus info: usb@1
       logical name: usb1
       version: 4.14
       capabilities: usb-2.00
       configuration: driver=hub slots=1 speed=480Mbit/s
     *-usb
          description: USB hub
          product: USB 2.0 Hub
          vendor: Standard Microsystems Corp.
          physical id: 1
          bus info: usb@1:1
          version: b.b3
          capabilities: usb-2.00
          configuration: driver=hub maxpower=2mA slots=4 speed=480Mbit/s
        *-usb:0
             description: USB hub
             product: USB 2.0 Hub
             vendor: Standard Microsystems Corp.
             physical id: 1
             bus info: usb@1:1.1
             version: b.b3
             capabilities: usb-2.00
             configuration: driver=hub maxpower=2mA slots=3 speed=480Mbit/s
           *-usb:0
                description: Generic USB device
                vendor: Standard Microsystems Corp.
                physical id: 1
                bus info: usb@1:1.1.1
                version: 3.00
                capabilities: usb-2.10
                configuration: driver=lan78xx maxpower=2mA speed=480Mbit/s
           *-usb:1
                description: Mass storage device
                product: Cruzer Fit
                vendor: SanDisk
                physical id: 2
                bus info: usb@1:1.1.2
                logical name: scsi0
                version: 1.00
                serial: 4C531001340803123251
                capabilities: usb-2.10 scsi emulated
                configuration: driver=usb-storage maxpower=224mA speed=480Mbit/s
              *-disk
                   description: SCSI Disk
                   product: Cruzer Fit
                   vendor: SanDisk
                   physical id: 0.0.0
                   bus info: scsi@0:0.0.0
                   logical name: /dev/sda
                   version: 1.00
                   serial: 4C531001340803123251
                   size: 29GiB (31GB)
                   capabilities: removable
                   configuration: ansiversion=6 logicalsectorsize=512 sectorsize=512
                 *-medium
                      physical id: 0
                      logical name: /dev/sda
                      size: 29GiB (31GB)
                      capabilities: partitioned partitioned:dos
                      configuration: signature=242ad76d
                    *-volume:0
                         description: Windows FAT volume
                         vendor: mkfs.fat
                         physical id: 1
                         logical name: /dev/sda1
                         logical name: /boot
                         version: FAT32
                         serial: 13c6-2676
                         size: 41MiB
                         capacity: 41MiB
                         capabilities: primary fat initialized
                         configuration: FATs=2 filesystem=fat label=boot mount.fstype=vfat mount.options=rw,relatime,fmask=0022,dmask=0022,codepage=437,iocharset=ascii,shortname=mixed,errors=remount-ro state=mounted
                    *-volume:1
                         description: EXT4 volume
                         vendor: Linux
                         physical id: 2
                         logical name: /dev/sda2
                         version: 1.0
                         serial: 45746d63-9d8a-4786-98fa-9a2311ffff35
                         size: 29GiB
                         capacity: 29GiB
                         capabilities: primary journaled extended_attributes large_files huge_files dir_nlink recover 64bit extents ext4 ext2 initialized
                         configuration: created=2017-09-03 18:52:48 filesystem=ext4 lastmountpoint=/ modified=2016-11-03 17:16:43 mounted=2018-04-02 15:37:27 state=clean
        *-usb:1
             description: Mass storage device
             product: Cruzer Fit
             vendor: SanDisk
             physical id: 3
             bus info: usb@1:1.3
             logical name: scsi1
             version: 1.00
             serial: 4C530001270910101572
             capabilities: usb-2.10 scsi emulated
             configuration: driver=usb-storage maxpower=224mA speed=480Mbit/s
           *-disk
                description: SCSI Disk
                product: Cruzer Fit
                vendor: SanDisk
                physical id: 0.0.0
                bus info: scsi@1:0.0.0
                logical name: /dev/sdb
                version: 1.00
                serial: 4C530001270910101572
                size: 58GiB (62GB)
                capabilities: removable
                configuration: ansiversion=6 logicalsectorsize=512 sectorsize=512
              *-medium
                   physical id: 0
                   logical name: /dev/sdb
                   size: 58GiB (62GB)
                   capabilities: partitioned partitioned:dos
                 *-volume
                      description: EXT4 volume
                      vendor: Linux
                      physical id: 1
                      logical name: /dev/sdb1
                      logical name: /motion
                      version: 1.0
                      serial: 1fa3f08b-cfa9-4dd6-ba63-b735f479b7c8
                      size: 58GiB
                      capacity: 58GiB
                      capabilities: primary journaled extended_attributes large_files huge_files dir_nlink recover 64bit extents ext4 ext2 initialized
                      configuration: created=2018-01-08 22:11:29 filesystem=ext4 lastmountpoint=/motion modified=2018-04-02 15:37:29 mount.fstype=ext4 mount.options=rw,noatime,data=ordered mounted=2018-04-02 15:37:29 state=mounted
  *-network:0
       description: Ethernet interface
       physical id: 2
       logical name: eth0
       serial: b8:27:eb:29:96:9c
       size: 1Gbit/s
       capacity: 1Gbit/s
       capabilities: ethernet physical tp mii 10bt 10bt-fd 100bt 100bt-fd 1000bt-fd autonegotiation
       configuration: autonegotiation=on broadcast=yes driver=lan78xx driverversion=1.0.6 duplex=full ip=10.10.10.16 link=yes multicast=yes port=MII speed=1Gbit/s
  *-network:1
       description: Wireless interface
       physical id: 3
       logical name: wlan0
       serial: b8:27:eb:7c:c3:c9
       capabilities: ethernet physical wireless
       configuration: broadcast=yes driver=brcmfmac driverversion=7.45.154 firmware=01-4fbe0b04 multicast=yes wireless=IEEE 802.11

[Peter Collinson (pcollinson)]

Spent some time today suspecting my network... and replacing switches to see if it's that. It doesn't seem to be.

It's not losing data - but is dropping incoming packets.
eth0: flags=4163<UP,BROADCAST,RUNNING,MULTICAST> mtu 1500
  ...
        RX packets 27620129 bytes 626133333 (597.1 MiB)
        RX errors 0 dropped 121 overruns 0 frame 0
        TX packets 10392537 bytes 1665351159 (1.5 GiB)
        TX errors 0 dropped 0 overruns 0 carrier 0 collisions 0
  ...

The machine is getting in files from another RPi with a camera - and making mp4s before shipping them elsewhere. So it's reasonably network intensive with large files coming and going.

I've added -K to the dhcpcd process which ignores carrier transitions and at least stops it taking down the interface and putting it back up again.