Tool/software:
We are experiencing an intermittent issue with the Ethernet interface on our system. When the Ethernet cable is continuously connected, the link remains stable, and network communication works fine. However, if we disconnect the cable for a few minutes (or sometimes hours) and then reconnect it, the link does not come back up automatically.
We need to manually bring the Ethernet interface down and up again to restore the connection. The issue is random—sometimes it occurs after a short disconnection, other times after hours, and occasionally it does not happen at all.
When the issue occurs, the following status is observed:
# cat /sys/class/net/eth0/carrier
0
# ip link show eth0
2: eth0: <NO-CARRIER,BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000
link/ether ce:92:2f:1a:a3:f8 brd ff:ff:ff:ff:ff:ff
# cat /sys/class/net/eth0/operstate
down
# ethtool eth0
Settings for eth0:
Supported ports: [ TP MII ]
Supported link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Supported pause frame use: Symmetric Receive-only
Supports auto-negotiation: Yes
Supported FEC modes: Not reported
Advertised link modes: 10baseT/Half 10baseT/Full
100baseT/Half 100baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Advertised FEC modes: Not reported
Speed: Unknown!
Duplex: Unknown! (255)
Auto-negotiation: on
Port: MII
PHYAD: 0
Transceiver: external
Current message level: 0x00000001 (1)
drv
Link detected: no
#
# dmesg | grep eth
[ 5.847423] ambarella-eth e000e000.ethernet: select RMII mode
[ 5.918519] ambarella-eth e000e000.ethernet: Ethernet PHY[0]: 0x2000a140, Fixed!
[ 5.936872] ambarella-eth e000e000.ethernet: using random Ethernet MAC
[ 5.954813] using random self ethernet address
[ 5.958439] ambarella-eth e000e000.ethernet: CONFIG_PTP_1588_CLOCK is not set
[ 5.968465] using random host ethernet address
[ 5.975373] ambarella-eth e000e000.ethernet: MAC Address[7a:63:51:f4:84:aa].
[ 5.996406] using random self ethernet address
[ 6.002130] using random host ethernet address
