跨网络的协议头？

Question

Question from my review I think I have correct.

When a packet is routed across a network, the protocol headers are modified as the packet is passed between intermediate nodes (eg routers). Why?

From what I can tell, the NAT (network address translation tool) modifies the source and destination header fields to reflect the new source (that router) and the new destination (if there is one). Is this correct?

Answer 1

是的，没错，数据包封装在链路层数据包中，其中包含当前路由器的MAC地址作为“源”，而下一个路由器的MAC地址作为该路由上的目的地，但应用层数据包不变，它仍然包含主源地址和最终目的地地址。