考虑以下拓扑：

想象一下，vPC 对等保持活动链接和 vPC 对等链接都已断开。我试图了解这将如何导致不可预测的流量或循环。

从我在 Cisco 文档上读到的内容：

If the vPC keepalive link fails first and then a peer 
link fails, the vPC secondary switch assumes the 
primary switch role and keeps its vPC member ports up.
If the peer link and keepalive link fails, there could 
be a chance that both vPC switches are healthy and the 
failure occurs because of a connectivity issue between 
the switches. In this situation, both vPC switches claim 
the primary switch role and keep the vPC member ports up. 
This situation is known as a split-brain scenario. Because 
the peer link is no longer available, the two vPC switches 
cannot synchronize the unicast MAC address and the IGMP 
group and therefore they cannot maintain the complete unicast 
and multicast forwarding table.

上面的我明白，但我想进一步深入研究循环是如何发生的。不可预测的交通场景将如何发生？我知道将有两个 vPC 主交换机（它们都将充当 STP 根）。您能否通过使用简单的拓扑来澄清？

在进一步搜索时，我在这里看到下面的帖子

据我了解，由于我们有 2 台交换机充当 vPC 主交换机（因此它们都将是 STP 根），因此链路将处于转发状态，因此有可能发生环路。这是正确的理解吗？我还想弄清楚，如果数据包来自 S1，那么它如何可能经历循环？