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Unformatted text preview: long that path. This form of dependency is called layering This layering
reliable ﬁle transfer is layered above packet transfer protocol reliable layered above network-wide packet delivery is layered above packet transfer over a network-wide layered above direct link between neighboring nodes it is like calling a subroutine within a program it Protocol stack
A set of protocol layers set Each layer uses the layer below and provides a service to the Each layer above Key idea Key
once we deﬁne a service provided by a layer, we need know once nothing more about the details of how the layer actually implements how the the service information hiding information decouples changes decouples Internet protocol stack
application: supporting network applications application:
FTP, SMTP, HTTP FTP, transport: process-process data transfer transport:
TCP, UDP TCP, application transport network link physical network: routing of datagrams from source to network: destination
IP, routing protocols IP, link: data transfer between neighboring network link: elements
PPP, Ethernet PPP, physical: bits “on the wire” physical: Layering: logical communication
Each layer: distributed distributed “entities” implement layer functions at each node entities perform entities actions, exchange messages with peers
application transport network link physical application transport network link physical network link physical application transport network link physical application transport network li...
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- Spring '10