1Gbps Ethernet drops to 100Mbps
Hi all,
I have a 1Gbps network port that correctly connects as 1Gbps full duplex
on boot, then drops to 100Mbps 4 seconds later.
Forcing 1Gbps full duplex with ethtool works fine. Tested to make sure
the actual speed is over 100Mbps.
I am trying to determine what causes the drop to 100Mbps and how to
avoid it.
The network port is on a Thunderbolt 3 hub in case this matters. Though
it appears that it looks just like a regular 1Gbps card to igb driver.
Tried two different Cat6 cables at 5 ft distance to the switch.
There is nothing aside from loopback in /etc/network/interfaces and
/etc/network/interfaces.d.
Relevant log entries:
# dmesg | grep -E '(igb|eth|enp9s0)'
[ 1.707669] wmi_bus wmi_bus-PNP0C14:01: WQBC data block query control
method not found
[ 5.578360] igb: Intel(R) Gigabit Ethernet Network Driver - version
5.4.0-k
[ 5.578360] igb: Copyright (c) 2007-2014 Intel Corporation.
[ 6.351902] igb 0000:09:00.0: added PHC on eth0
[ 6.351903] igb 0000:09:00.0: Intel(R) Gigabit Ethernet Network
Connection
[ 6.351904] igb 0000:09:00.0: eth0: (PCIe:2.5Gb/s:Width x1)
64:4b:f0:10:5e:80
[ 6.352004] igb 0000:09:00.0: eth0: PBA No: 000300-000
[ 6.352005] igb 0000:09:00.0: Using MSI-X interrupts. 4 rx queue(s),
4 tx queue(s)
[ 6.352464] igb 0000:09:00.0 enp9s0: renamed from eth0
[ 71.234244] IPv6: ADDRCONF(NETDEV_UP): enp9s0: link is not ready
[ 71.262391] IPv6: ADDRCONF(NETDEV_UP): enp9s0: link is not ready
[ 74.272257] igb 0000:09:00.0 enp9s0: igb: enp9s0 NIC Link is Up 1000
Mbps Full Duplex, Flow Control: RX/TX
[ 74.487967] IPv6: ADDRCONF(NETDEV_CHANGE): enp9s0: link becomes ready
[ 78.623864] igb 0000:09:00.0 enp9s0: igb: enp9s0 NIC Link is Up 100
Mbps Half Duplex, Flow Control: None
[ 78.623869] igb 0000:09:00.0: EEE Disabled: unsupported at half
duplex. Re-enable using ethtool when at full duplex.
Then forcing with ehttool:
# ethtool -s enp9s0 speed 1000 duplex full
# dmesg | grep -E '(igb|eth|enp9s0)'
...
[ 346.656896] igb 0000:09:00.0 enp9s0: igb: enp9s0 NIC Link is Up 1000
Mbps Full Duplex, Flow Control: RX/TX
Any ideas would be much appreciated. Thanks.
--
Nazar
Reply to: