eth2 Stuck At 100MB

Asset ID:	1-72-2313199.1
Update Date:	2017-10-02
Keywords:

Solution Type Problem Resolution Sure

Solution 2313199.1 : eth2 Stuck At 100MB

Applies to:

Exadata X4-2 Half Rack - Version All Versions to All Versions [Release All Releases]
Information in this document applies to any platform.

Symptoms

eth2 which is part of bondeth0 is only coming up at 100Mb. eth1 which is also part of bondeth0 is running at the expected speed of 1000Mb.

#ethtool eth1
Settings for eth1:
Supported ports: [ TP ]
Supported link modes: 100baseT/Full <-------------------NiICSupported Speeds 100,1000,10000
1000baseT/Full
10000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 100baseT/Full <---------------NIC advertising speeds of 100, 1000, 10000
1000baseT/Full
10000baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Speed: 1000Mb/s<-------------------------------------Expected Speed
Duplex: Full
Port: Twisted Pair
PHYAD: 0
Transceiver: external
Auto-negotiation: on
MDI-X: Unknown
Supports Wake-on: d
Wake-on: d
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes

# ethtool eth2
Settings for eth2:
Supported ports: [ TP ]
Supported link modes: 100baseT/Full<-------------------NIC Supported Speeds 100,1000,10000
1000baseT/Full
10000baseT/Full
Supported pause frame use: No
Supports auto-negotiation: Yes
Advertised link modes: 100baseT/Full<---------------NIC advertising speeds of 100, 1000, 10000
1000baseT/Full
10000baseT/Full
Advertised pause frame use: No
Advertised auto-negotiation: Yes
Speed: 100Mb/s <------------------------------Current link speed dropped to 100Mb
Duplex: Full
Port: Twisted Pair
PHYAD: 0
Transceiver: external
Auto-negotiation: on
MDI-X: Unknown
Supports Wake-on: d
Wake-on: d
Current message level: 0x00000007 (7)
drv probe link
Link detected: yes

Cause

Possibilities include a defective cable, a mis configured switch port only offering 100Mb, mis configured NIC port on the system, or a defective NIC port.

Solution

Standard steps to isolate to switch port, NIC port, or cable would include the following:

- During a maintenance window , move/reverse the cables in the bond. In this example the cable on eth2 was moved to eth1 and the cable on eth1 was moved to eth2. This is the quickest way to isolate to the system/NIC side, or the cable/switch side.

- If the problem follows the cable (IE: problem moved to eth1 and now eth2 is up at 1000Mb), then check the uplink switch port configuration (speed, duplex settings, errors) and or replace he cable with a known good cable.

- If the problem remains with eth2 and eth1 now comes up at 1000Mb after the cable move, then the problem is on the system side. Check configuration settings using ethtool, check ILOM snapshot for related hardware errors, replace the NIC card as a last resort.

In some cases a Customer can not take a maintenance window and take down the healthy link in the bond (eth1 in this example) . In this case, the cable and or uplink switch port can still be investigated by checking uplink port configuration, checking host side port configuration, replacing the cable, connecting a known working 1000Mb connection to the port such as a lap top and then checking ethtool to see if the port will link to 1000Mb.

References

<NOTE:2169185.1> - Oracle Linux: Link Speed of Ethernet Interface is Changed from 1Gbps to 100Mbps with out configuration changes

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