>> As illustrated, MAC addresses are only locally significant and are definitely neededin addition to IP addresses to specify the next hop to receive the packetand route to its final destination.
>>如图示，MAC地址仅在本地有效，除了IP地址之外，还必须指定下一跳以接收数据包并路由到其最终目的地。
Every time a packet passes through an interface, the frame is stripped off and discardedand after the next router figures out the next hop,the packet is reframed with a new outer frame.
每一次数据包通过一个接口，帧就被剥离并丢弃，在下一个路由器计算出下一跳之后，该数据包就被重新构建为一个新的外部帧。
IP addresses are logical and for the most part geographical and hierarchical like zip codes.
IP地址是逻辑的，并且在很大程度上像邮政编码一样具有地理和层次结构。
If I send a UPS package from Rochester to Staten Island,the first UPS distribution center sends it to the next one.
如果我把一个UPS包裹从罗切斯特寄到史坦顿岛，第一个UPS配送中心会把它寄到下一个。
And the second distribution center sends it to the third.
第二个配送中心把它送到第三个配送中心。
The tracking of packages is made possible with UPS routing stickers slappedon the UPS packages going out of each distribution facility to the next facility.
包裹的跟踪是可能的UPS路由贴纸贴在UPS包裹走出每个配送设施到下一个设施。
Think of those as the MAC addresses.
这些是MAC地址。
As a package leaves a UPS distribution center, the sticker indicateswhich distribution center it's leaving and which distribution center it's destined for.
当一个包裹离开UPS的配送中心时，标签会标明它将离开哪个配送中心以及它将前往哪个配送中心。
When it gets to the next distribution center, those stickers are removed.
当它到达下一个配送中心时，这些贴纸就会被移除。
That's just like the Ethernet frames in our networking story, which are removedand added back with each router that a packet passes through.
这就像我们的网络故事中的以太网帧一样，每个数据包通过的路由器都会删除和添加以太网帧。
However, on that brown box are to and from addresses which represent the actual personand source location sending the package and the actual personand destination that the package is meant for.
但是，在这个棕色的框上是往返地址，这些地址表示发送包的实际人员和源位置，以及包的实际人员和目的地。
Those are of course analogous to the source and destination IP addresses in our story.
这些当然类似于我们故事中的源IP地址和目标IP地址。
The IP addresses just like the to and from addresses are geographical and never changethrough the duration of the path the packet or package takes to the final destination
IP地址，就像从地址到地址的地址是地理的，永远不会改变包裹或包裹到达最终目的地的路径
转载于:https://www.cnblogs.com/sec875/articles/10344649.html
