At this point I was convinced the implementation by the ISP was at the very least against best practices and quite possibly against the standards. I suspected the ISP was arriving at the same conclusion, as it installed an intermediate router between their equipment and the LAN switch to provide a possible quick fix, as shown in Figure 2.

The ISP router had two Gigabit interfaces: one with auto-negotiation enabled, the other disabled. The first connected to the LAN switch and the second to the ISP equipment. All links came up and the problem was resolved, yet the question of where the fault lay was still up in the air.

Epilogue

A short time later the LAN switch manufacturer presented its official stance. According to its interpretation of the standard, the option to operate with auto-negotiation disabled was included to ensure interoperability with Gigabit equipment produced prior to the adoption of Clause 37. This was to overcome the determination of the master/slave relationship. Equipment with auto-negotiation disabled would act as the master. Equipment with auto-negotiation enabled would start the negotiation process as master. Thus, two masters could not communicate.

The LAN switch manufacturer went on to say that while it could possibly write code to circumvent this, in its opinion that was against the standard. Further research found an instancewhereby the IEEE agreed that such interpretation constitutes a request to change the standards. The final decision by the manufacturer was to maintain strict adherence to the standards, a move I completely agreed with.