Original question:
您好，
看下面手册截图，DUPLEX STATUS位只有在启用并完成自动协商且存在有效链接时，或者如果禁用了自动协商且存在有效链接时，此位才有效（Note: This bit is only valid if Auto-Negotiation is enabled and complete and there is a valid link or if Auto-Negotiation is disabled and there is a valid link.）
