计算机网络与互联网(英语)chap9课件.pptVIP

Summary LAN technologies use hardware addresses to identify destination for frames sent across shared communication channel Each LAN technology defines its own hardware format Addresses may be statically assigned, configurable or dynamically assigned Summary Frames include a header with fields for destination, source and other information such as frame type Frame type defines how to interpret frame data Network analyzer can receive all frames and display statistics or aid in debugging problems * Chapter 9 Hardware AddressingandFrame Type Identification Content Describes: hardware addressing how a sending computer uses a hardware address to identify which computer or computers should receive a copy of a given frame how network interface hardware uses such address to filter incoming packets a mechanism that allows a sender to identify the type of the data in each frame How identify a computer in network? Identifying a Destination Data sent across a shared network reaches all attached stations But ... most applications want data to be delivered to one specific application on another computer - not all computers To allow sender to specify destination Each station assigned unique number Known as station’s address Each frame contains address of intended recipient Assignment of physical address Most network technologies have a hardware addressing scheme that identifies stations on the network Each station is assigned a numeric hardware address or physical address Sender includes destination hardware address in each transmitted frame physical address physical address also called MAC addresses /hardware address/NIC address physical address help identify the computer Sometimes referred to as burned-in addresses (BIAs)because they are burned into read-only memory (ROM) and are copied into random-access memory (RAM) when the NIC initializes Specifying Recipients Address Each frame transmitted across a shared LAN includes two addresses One that specifies the intende