I contacted the ISP to determine the proper settings. The LAN switch defaulted to auto-negotiation enabled for all Gigabit Ethernet ports. The ISP indicated that its equipment was configured for no auto-negotiation. The manual settings the ISP required were basic: speed set at 1Gbit/sec., duplex set to full and auto-negotiation disabled. And it requested the LAN switch be manually configured accordingly.

Although I was mildly bothered by the fact the ISP required manual settings, I fully expected to have the link come up when I configured the switch interface with these values. Unfortunately, the link light did not illuminate. No link light generally means no connectivity, and this was no exception. Saving the new configuration and rebooting the switch had no effect.

The pointing begins

My experiences with 100Mbit/sec. twisted pair connections have been that often auto-negotiation should be turned off and the settings forced, so the ISP's request seemed to make sense. However, with Gigabit Ethernet connections I have always had excellent success with having both ends set for auto-negotiation. A colleague had once expressed the Ethernet auto-negotiation practices as such: for 1Gbit/sec., enable; for 100Mbit/sec. disable; for 10Mbit/sec., upgrade.

I contacted the LAN switch manufacturer and opened a trouble ticket to determine if its equipment was at fault. I also asked the ISP if it could enable auto-negotiation for testing. When it did, the interface came up. Therefore, the simplest answer seemed to be to leave auto-negotiation enabled. However, the ISP said because of its network design that was not possible.