Introduction to host to host communications (OSI Model and TCP/IP Model)

Host-to-host communications require a consistent model.

 Two different types of host-to-host models:

 1) Older model:
   a) Proprietary
   b) Applications and combinations of software controlled by one vendor.

 2) Standard based model:
   a) Multivendor software
   b) Layered approach
   c) Example: OSI, TCP/IP

 1) OSI Model:


a) Physical Layer: The electrical, mechanical, procedural, and functional specifications for activating, maintaining and deactivating the physical link for bit transmission between end devices.

b) Data Link Layer : How data is formatted for transmission and access media is controlled.

c) Network Layer: Connection and path selection between two hosts.

d) Transport Layer: Segment, transfer and reassemble data between devices.

e) Session Layer: Establish, manages, terminates communication between hosts.

f) Presentation Layer: Information sent from one host is readable by another hosts.

g) Application Layer: Provides network services to application of users eg. Email.


2) TCP/IP Protocol Suite: 



a) Application Layer: Provides applications for files transfer, network troubleshooting.

b) Transport Layer: Communication services to applications.

c) Internet Layer: Routing data from source to destination.

d) Link Layer: How access is controlled and how data is formatted for transmission.

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