smaller (often regional) ISPs Connect to one or more tier-1

closest to end systems

Packets passed from node to node between source and destination.

TCP/IP is more

minimizes the number of layers used and makes more focus on the practical issues than the theoretical issues

ISO/OSI is more

in ISO all layers have the same Functions

OSI has ......... layers

Layers: Application, Transport, Internet, Network access

OSI

The layer boundaries should be chosen tomaximize the information flow across the interfaces

It prevents changes in one layer from affecting the other layers, so that they can develop more quickly.

Which layer of the OSI model provides services to enable user interactions with applications, such as email or web browsing?

Provides an error-free communication link

ransmission of raw bits over a communication channe

Issues: Physical Addressing & Error detection, framing

Media Access Control (MAC) sub-layer for providing DLC with “virtual wires” on multi-access

Which layer of the OSI model is responsible for converting data into a format suitable for transmission over a network?

Issues: Mechanical interfaces, Electrical or optical interfaces, Time per bit, Distances between nodes

Which layer of the OSI model provides reliable, end-to-end data delivery and ensures that data packets are delivered in the correct order?

Which layer of the OSI model deals with the physical transmission of data over a network medium?