在城域网交换机日常维护中经常会发现，一些申告有丢包、大延时甚至瞬间

中断的以太网专线接入故障中都是因为交换机端口设置不规范，将速率和双工模

式设成了自动协商，如果光电收发器和用户端口也都设置为这一状态，那么会导

致使用设置为10Mbps/100Mbps 自适应的光收发器和用户端网卡用户，实际接入

速率为全双工100Mbps，这样的话该用户的实际吞吐能力可达到200Mbps；另一

方面，因有些光收发器或用户端设备不具备自协商功能或被设置为10Mbps

(100Mbps) 全双工， 从而导致交换机端口于用户端设备自协商到10Mbps

（100Mbps）半双工，进而导致接入链路延时大、丢包乃至瞬间中断。-MAN switch in the routine maintenance is often found that some declaration have packet loss, delay or even big moment

Ethernet Private Line Access interrupted because of failure in the switch port settings are not standardized, the speed and duplex mode

Type set into auto-negotiation, if the optical transceiver and the user ports are also set to this state, will lead

To use the set to 10Mbps/100Mbps adaptive optical transceivers and client card users, the actual access

Rate full-duplex 100Mbps, so the actual throughput of the user can achieve 200Mbps　another

Respect, because some optical transceiver or CPE does not have auto-negotiation function or set to 10Mbps

(100Mbps) full duplex, leading to a switch port on the CPE from the negotiation to 10Mbps

(100Mbps) half duplex, which led to major access link delay, packet loss and even the moment interrupted.