Computer Networks. Marwan Al- Namari Week 4. 7 Layers. OSI Layer Communication. Application. Application. Presentation. Presentation. Physical Path. Session. Session. Logical Path. Transport. Transport. Network. Network. Data Link. Physical. Data Link. Physical Medium.
Each layer add its own header (and maybe trailer ) to the portion of the packet and pass it to the next layer without knowing which part is data and header( and maybe trailer ).it treat it as one integral unit.
The concept is called encapsulation.
In the way back each layer will take-off the header ( and maybe trailer ) from the incoming packet and pass it to the next layer .
The concept is called decapsulation.
Cyclical Redundancy Check
The Internet Engineering Task Force (IETF) is the body that defines standard internet operating protocols
These standards are specified in documents called RFCs ( Requests for comments)
e.g. RFC 821 is about SMTP ( e-mail) protocols
TCP/IP : Transmission Control Protocol /Internet Protocol.
It is a suite of protocols providing communications in a heterogeneous environment.
It is used for interoperability among many different types of computers.
Almost all networks support TCP/IP.
Used as internetworking protocol.
These protocols were written specifically for TCP/IP:
SMTP(Simple Mail Transfer Protocol) : Email
FTP (File Transfer Protocol) : For exchanging files .
SNMP(Simple Network Management Protocol) :Network Management.