Once frozen, TIME_WAIT connections never expire, ephemeral ports slowly exhaust, and eventually no new TCP connections can be established at all. ICMP (ping) keeps working. Everything else dies.
大多数人认为操作系统崩溃才会导致网络完全失效,但作者认为macOS可以在看似完全正常的情况下陷入网络瘫痪状态,因为只有TCP协议栈失效而ICMP仍能工作。这种'部分系统死亡'的状态非常反直觉,因为系统不会崩溃或报错,只是TCP连接停止工作。