In my Fibre Optic device (Linux 2.6.27, LXT971A PHY Transceiver), connection to the port is lost intermittently. While debugging with ETHtool, the following observation was observed:

Settings for eth0: Supported ports: [ TP MII ] Supported link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Supported pause frame use: No Supports auto-negotiation: Yes Advertised link modes: 10baseT/Half 10baseT/Full 100baseT/Half 100baseT/Full Advertised pause frame use: No Advertised auto-negotiation: Yes Speed: 1000Mb/s Duplex: Full Port: MII PHYAD: 0 Transceiver: external Auto-negotiation: off Link detected: yes

The Switch used (ruggedcom) supports only 100Mb/s FULL DUPLEX . Why is the speed moved to 1000Mb/s and the link detected is "yes" ? After this stage is reached the port will not try any other speed and stays in 1000Mb/s until device restart. Please note that the issue is observed only with a FO cable of length 30m or more and works fine with FO cable of length 2m.

Any comments or insights are greatly appreciated.

  • The BMCR and BMSR are in the following Modes: BMCR = 2100 (100Mbps,full duplex) BMSR = 780D – karthikkumar Nov 14 '17 at 6:37
  • You need to add hardware details. The Intel LXT971A is a 10BASE-T/100BASE-TX copper transceiver. Are you using fiber or twisted pair?? – Zac67 Jan 19 '18 at 7:25

Your Answer

By clicking "Post Your Answer", you acknowledge that you have read our updated terms of service, privacy policy and cookie policy, and that your continued use of the website is subject to these policies.

Browse other questions tagged or ask your own question.