Explain about OSI reference model
Explain about OSI reference model.
11. Explain about OSI reference model. Also describe other network models.
The OSI, or Open System Interconnection, model defines a networking framework to implement protocols in seven layers. Control is passed from one layer to the next, starting at the application layer in one station, and proceeding to the bottom layer, over the channel to the next station and back up the hierarchy.
The OSI model takes the task of internetworking and divides that up into what is referred to as a vertical stack that consists of the following layers:
What is SAP R3 Architecture ?
What is SAP R3 Architecture ?
Physical (Layer 1)
This layer conveys the bit stream – electrical impulse, light or radio signal — through the network at the electrical and mechanical level. It provides the hardware means of sending and receiving data on a carrier, including defining cables, cards and physical aspects. Fast Ethernet, RS232, and ATM are protocols with physical layer components.
Layer 1 Physical examples include Ethernet, RJ45.
Data Link (Layer 2)
At this layer, data packets are encoded and decoded into bits. It furnishes transmission protocol knowledge and management and handles errors in the physical layer, flow control and frame synchronization. The data link layer is divided into two sub layers: The Media Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC sub layer controls how a computer on the network gains access to the data and permission to transmit it. The LLC layer controls frame synchronization, flow control and error checking.
– Layer 2 Data Link examples include PPP, ATM, IEEE, Frame Relay,
Network (Layer 3)
This layer provides switching and routing technologies, creating logical paths, known as virtual circuits, for transmitting data from node to node. Routing and forwarding are functions of this layer, as well as addressing, internetworking, error handling, congestion control and packet sequencing.
– Layer 3 Network examples include AppleTalk DDP, IP, IPX.
Transport (Layer 4)
This layer provides transparent transfer of data between end systems, or hosts, and is responsible for end-to-end error recovery and flow control. It ensures complete data transfer.
– Layer 4 Transport examples include SPX, TCP, UDP.
Session (Layer 5)
This layer establishes, manages and terminates connections between applications. The session layer sets up, coordinates, and terminates conversations, exchanges, and dialogues between the applications at each end. It deals with session and connection coordination.
– Layer 5 Session examples include NFS, NetBios names, RPC, SQL.
Presentation (Layer 6)
This layer provides independence from differences in data representation (e.g., encryption) by translating from application to network format, and vice versa. The presentation layer works to transform data into the form that the application layer can accept. This layer formats and encrypts data to be sent across a network, providing freedom from compatibility problems. It is sometimes called the syntax layer.
– Layer 6 Presentation examples include encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI.
Application (Layer 7)
This layer supports application and end-user processes. Communication partners are identified, quality of service is identified, user authentication and privacy are considered, and any constraints on data syntax are identified. Everything at this layer is application-specific. This layer provides application services for file transfers, e-mail, and other network software services. Telnet and FTP are applications that exist entirely in the application level. Tiered application architectures are part of this layer.
SAP Client Copy – Local, Remote & Import / export
– Layer 7 Application examples include WWW browsers, NFS, SNMP, Telnet, HTTP, FTP.
Explain about OSI reference model
Explain about OSI reference model.
11. Explain about OSI reference model. Also describe other network models.
The OSI, or Open System Interconnection, model
defines a networking framework to implement protocols in seven layers. Control
is passed from one layer to the next, starting at the application layer in one
station, and proceeding to the bottom layer, over the channel to the next
station and back up the hierarchy.
defines a networking framework to implement protocols in seven layers. Control
is passed from one layer to the next, starting at the application layer in one
station, and proceeding to the bottom layer, over the channel to the next
station and back up the hierarchy.
The OSI model takes the task of internetworking
and divides that up into what is referred to as a vertical stack that consists
of the following layers:
and divides that up into what is referred to as a vertical stack that consists
of the following layers:
Physical (Layer 1)
This layer conveys the bit stream – electrical
impulse, light or radio signal — through the network at the electrical and
mechanical level. It provides the hardware means of sending and receiving data
on a carrier, including defining cables, cards and physical aspects. Fast
Ethernet, RS232, and ATM are protocols with physical layer components.
impulse, light or radio signal — through the network at the electrical and
mechanical level. It provides the hardware means of sending and receiving data
on a carrier, including defining cables, cards and physical aspects. Fast
Ethernet, RS232, and ATM are protocols with physical layer components.
Layer 1 Physical examples include Ethernet,
RJ45.
RJ45.
Data Link (Layer 2)
At this layer, data packets are encoded and
decoded into bits. It furnishes transmission protocol knowledge and management
and handles errors in the physical layer, flow control and frame
synchronization. The data link layer is divided into two sub layers: The Media
Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC
sub layer controls how a computer on the network gains access to the data and
permission to transmit it. The LLC layer controls frame synchronization, flow
control and error checking.
decoded into bits. It furnishes transmission protocol knowledge and management
and handles errors in the physical layer, flow control and frame
synchronization. The data link layer is divided into two sub layers: The Media
Access Control (MAC) layer and the Logical Link Control (LLC) layer. The MAC
sub layer controls how a computer on the network gains access to the data and
permission to transmit it. The LLC layer controls frame synchronization, flow
control and error checking.
– Layer 2 Data Link examples include PPP, ATM,
IEEE, Frame Relay,
IEEE, Frame Relay,
Network (Layer 3)
This layer provides switching and routing
technologies, creating logical paths, known as virtual circuits, for
transmitting data from node to node. Routing and forwarding are functions of
this layer, as well as addressing, internetworking, error handling, congestion
control and packet sequencing.
technologies, creating logical paths, known as virtual circuits, for
transmitting data from node to node. Routing and forwarding are functions of
this layer, as well as addressing, internetworking, error handling, congestion
control and packet sequencing.
– Layer 3 Network examples include AppleTalk
DDP, IP, IPX.
DDP, IP, IPX.
Transport (Layer 4)
This layer provides transparent transfer of
data between end systems, or hosts, and is responsible for end-to-end error
recovery and flow control. It ensures complete data transfer.
data between end systems, or hosts, and is responsible for end-to-end error
recovery and flow control. It ensures complete data transfer.
– Layer 4 Transport examples include SPX, TCP,
UDP.
UDP.
Session (Layer 5)
This layer establishes, manages and terminates
connections between applications. The session layer sets up, coordinates, and
terminates conversations, exchanges, and dialogues between the applications at
each end. It deals with session and connection coordination.
connections between applications. The session layer sets up, coordinates, and
terminates conversations, exchanges, and dialogues between the applications at
each end. It deals with session and connection coordination.
– Layer 5 Session examples include NFS, NetBios
names, RPC, SQL.
names, RPC, SQL.
Presentation (Layer 6)
This layer provides independence from
differences in data representation (e.g., encryption) by translating from
application to network format, and vice versa. The presentation layer works to
transform data into the form that the application layer can accept. This layer
formats and encrypts data to be sent across a network, providing freedom from
compatibility problems. It is sometimes called the syntax layer.
differences in data representation (e.g., encryption) by translating from
application to network format, and vice versa. The presentation layer works to
transform data into the form that the application layer can accept. This layer
formats and encrypts data to be sent across a network, providing freedom from
compatibility problems. It is sometimes called the syntax layer.
– Layer 6 Presentation examples include
encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI.
encryption, ASCII, EBCDIC, TIFF, GIF, PICT, JPEG, MPEG, MIDI.
Application (Layer 7)
This layer supports application and end-user
processes. Communication partners are identified, quality of service is
identified, user authentication and privacy are considered, and any constraints
on data syntax are identified. Everything at this layer is
application-specific. This layer provides application services for file
transfers, e-mail, and other network software services. Telnet and FTP are
applications that exist entirely in the application level. Tiered application
architectures are part of this layer.
processes. Communication partners are identified, quality of service is
identified, user authentication and privacy are considered, and any constraints
on data syntax are identified. Everything at this layer is
application-specific. This layer provides application services for file
transfers, e-mail, and other network software services. Telnet and FTP are
applications that exist entirely in the application level. Tiered application
architectures are part of this layer.
– Layer 7 Application examples include WWW
browsers, NFS, SNMP, Telnet, HTTP, FTP.
browsers, NFS, SNMP, Telnet, HTTP, FTP.
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