Chapter 8 - 13. Congestion Management in TCP Storage Networks

Switch Buffer Management

Recall that during network congestion, a TCP sender relies on the following events for reducing its transmission rate. 回想一下，在网络拥塞期间，TCP 发送端依靠以下事件来降低传输速率。

1. When the sender detects packet loss because of the following reasons. 当发送方因以下原因检测到数据包丢失时。

a. Retransmission timeout (RTO) or重传超时 (RTO) 或

b. Receiving third duplicate ACK (Fast Retransmission). 收到第三个重复 ACK（快速重传）。

2. When the sender receives an ECE-marked TCP packet. 当发送方收到 ECE 标记的 TCP 数据包时。

Both events originate at a network port when its queues fill up. This means that the packet drops or marking scheme on a switch can significantly influence TCP’s behavior on the end devices, and hence, these schemes are important in handling congestion in TCP networks. 这两种事件都源于网络端口的队列填满。这意味着，交换机上的数据包丢弃或标记方案会极大地影响 TCP 在终端设备上的行为，因此，这些方案在处理 TCP 网络拥塞时非常重要。

This section explains various states of queues on a network port. These queues are created in the switch buffers, hence the use of the term—Buffer Management. The queues have their own Active Queue Management mechanism as explained later. 本节介绍网络端口上队列的各种状态。这些队列在交换机缓冲区中创建，因此使用了缓冲区管理（Buffer Management