计算机网络自顶向下方法

One’sunderstandingofnetworkprotocolscanoftenbegreatlydeepenedby“seeingprotocolsinaction”andby“playingaroundwithprotocols”–observingthesequenceofmessagesexchangedbetweentwoprotocolentities,delvingdownintothedetailsofprotocoloperation,andcausingprotocolstoperformcertainactionsandthenobs