Ccna Internetworking Concepts

Front 1

What are some reasons that the industry uses a layered model?

Back 1

Here are some reasons why the industry uses a layered model:

· It encourages industry standardization by defining what
functions occur at each level.
· It allows vendors to modify or improve components at only one layer versus rewriting the whole protocol stack.
· It helps interoperability by defining standards for the
operations at each level.
· It helps with troubleshooting.

Front 2

What does the application layer (Layer 7) of the OSI model do, and what are some examples of this layer?

Back 2

The application layer is the layer that is closest to the user. This means that this layer interacts directly with the software application. The application layer's main function is to identify and establish communication partners, determine resource availability, and synchronize communication. Some examples include the following:

· TCP/IP applications such as Telnet, File Transfer Protocol
(FTP), Simple Mail Transfer Protocol (SMTP), WWW, and HTTP.
· OSI applications such as Virtual Terminal Protocol, File
Transfer, Access, and Management (FTAM), and Common Management
Information Protocol (CMIP).

Front 3

In the OSI model, what are the responsibilities of the presentation layer (Layer 6)? Give some examples of this layer.

Back 3

Also known as the translator, the presentation layer provides coding and conversion functions to application layer data. This guarantees that the application layer on another system can read data transferred from the application layer of a different system. Some examples of the presentation layer are

· Compression, decompression, and encryption
· JPEG, TIFF, GIFF, PICT, QuickTime, MPEG, and ASCII

Front 4

What are the functions of the session layer (Layer 5)? Give some examples.

Back 4

The session layer is responsible for creating, managing, and ending communication sessions between presentation layer entities. These sessions consist of service requests and responses that develop between applications located on different network devices. Some examples include SQL, RPC, NFS, X Window System, ZIP, NetBIOS names, and AppleTalk ASP.

Front 5

What is the transport layer (Layer 4) responsible for? Give some examples of transport layer implementations.

Back 5

The transport layer segments and reassembles data from upper-layer applications into data streams. It provides reliable data transmission to upper layers. End-to-end communications, flow control, multiplexing, error detection and correction, and virtual circuit management are typical transport layer functions. Some examples include TCP, UDP, and SPX.