Links are an entirely abstract notion, representing a service providing per-hop transport for IP packets. Often our poor brains cope by asserting that links are built from technologies at layers below IP or that links have a one-to-one relationship to the physical path between two points. But in the real world, this is rarely the case. Conventional link-level paths frequently do not exist between two points that desire to exchange packets even though a packet transport service may exist at the IP, UDP, or TCP level.


我的理解是两个points之间的一条"直接相连的链路(directly connected link)“

就是链路路径的意思，一般是逻辑上的

引用:

就是链路路径的意思，一般是逻辑上的

这里指的是物理上的。