Chapter 2 - 14. Understanding Congestion in Fibre Channel Fabrics

Ability to Detect and Drop CRC Corrupted Frames

As mentioned, a store-and-forward switch can detect and drop CRC-corrupted frames because the frame is received in its entirety before starting to transmit it on an egress port. This allows inspection of the CRC field, which is present at the end of a frame. Dropping the CRC corrupted frames where they are detected has the following benefits: 如前所述，存储转发交换机可以检测并丢弃 CRC 损坏的帧，因为在出口端口开始传输帧之前，已经接收了整个帧。这样就可以检查帧末尾的 CRC 字段。丢弃检测到的 CRC 损坏帧有以下好处：

 Saving the egress port bandwidth by not forwarding corrupt frames. 通过不转发损坏的帧来节省出口端口带宽。

 Saving the B2B credits by not forwarding corrupt frames. 不转发损坏的帧，从而节省 B2B 信元。

 Sending only good frames to the destination. 只向目的地发送良好帧

 Accurate and faster troubleshooting (Frames with CRC errors are seen only on interfaces where actual corruption is occurring on the link). 更准确、更快速地排除故障（只有在链路发生实际损坏的接口上，才会看到有 CRC 错误的报文）。

These benefits are not available with switches that use cut-through architecture because the switch starts sending the frame before seeing the end of it, the CRC field can be verified but the frames can’t be dropped on the ingress port or even on the egress port.

原文地址：https://blog.csdn.net/mounter625/article/details/143811543

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