The OSI (Open Systems Interconnection) Model
The OSI Model is a seven layered model to describe the interaction of network communication. The Model consists of seven layers used to identify an abstract function within network communications. Each specific layer can only interact with either a layer directly above or below itself, therefore it's possible to map each layer to a protocol or device used in network communications. The OSI model was original intended to be used as part of the OSI protocol suite, however today has been superseded and is now assigned to an abstract/reference role.
The seven layers consit of:1. Phyisical
2. Data Link
3. Network
4. Transport
5. Session
6. Presentation
7. Application
The Phyisical Layer:
The layer defines all things as suggested by the name phyisical. It's primary concern is the transmission of bits over to the next device in the network. This includes all things mechanical, electrical such as; transmission mediums, cabling, electric voltages, and light values for bit representation.
Data Term used at this Level:
Bits.
Network Devices that operate at this level:
Hubs, Repeaters, Analogue Modems.
The Data-Link Layer:
This layer is primarily concerned with the transfer of bits from one device to the next device on the line. This layer is used to also provide error correction to the phyisical layer. While higher up layers such as the transport also provide error correction, this layer also does a basic check to ensure the frame was transmitted correctly.
Data Term used at this Level:
Frames.
Network Devices/Protocols that operate at this level:
Ethernet, Frame Relay, PPP, Token Ring, 802.11, Spanning Tree Protocol.
The Network Layer:
The Network Layer is the highest level in the OSI model that's specifical related to networks, as the higher ones specifically relate to hosts on the network. The layer is responsible for delivery of packets to multiple hosts on a network beyond the data link or next device, involving the use of routing protocols, addressing schemes and delivery mechanisms.
Data Term used at this Level:
Packets.
Network Devices/Protocols that operate at this level:
IPv4, IPv6, ICMP, PIM, IGMP, ICMP,OSPF, EIGRP, RIP, and IPX.
The Transport Layer:
The Transport layer is concerned with the establishment of network communication between two end points on the network, these can be either connection oriented or connectionless.
Data Term used at this Level:
Segment.
Network Devices/Protocols that operate at this level:
TCP, UDP and SPX.
The Session Layer:
Data Term used at this Level:
Data.
Network Protocols that operate at this level:
L2TP, PPTP, SCP, SIP, SDP, and PAP
The Presentation Layer:
Data Term used at this Level:
Data.
Protocols that operate at this level:
NDR, AFP, XDR and NCP.
The Application Layer:
Data Term used at this Level:
Data.
Network Devices/Protocols that operate at this level:
BitTorrent, HTTP, Telnet, SSH, SMB, NTP, BGP, FTP and TFTP.
The OSI Model is a seven layered model to describe the interaction of network communication. The Model consists of seven layers used to identify an abstract function within network communications. Each specific layer can only interact with either a layer directly above or below itself, therefore it's possible to map each layer to a protocol or device used in network communications. The OSI model was original intended to be used as part of the OSI protocol suite, however today has been superseded and is now assigned to an abstract/reference role.
The seven layers consit of:
The Phyisical Layer:
The layer defines all things as suggested by the name phyisical. It's primary concern is the transmission of bits over to the next device in the network. This includes all things mechanical, electrical such as; transmission mediums, cabling, electric voltages, and light values for bit representation.
Data Term used at this Level:
Bits.
Network Devices that operate at this level:
Hubs, Repeaters, Analogue Modems.
The Data-Link Layer:
This layer is primarily concerned with the transfer of bits from one device to the next device on the line. This layer is used to also provide error correction to the phyisical layer. While higher up layers such as the transport also provide error correction, this layer also does a basic check to ensure the frame was transmitted correctly.
Data Term used at this Level:
Frames.
Network Devices/Protocols that operate at this level:
Ethernet, Frame Relay, PPP, Token Ring, 802.11, Spanning Tree Protocol.
The Network Layer:
The Network Layer is the highest level in the OSI model that's specifical related to networks, as the higher ones specifically relate to hosts on the network. The layer is responsible for delivery of packets to multiple hosts on a network beyond the data link or next device, involving the use of routing protocols, addressing schemes and delivery mechanisms.
Data Term used at this Level:
Packets.
Network Devices/Protocols that operate at this level:
IPv4, IPv6, ICMP, PIM, IGMP, ICMP,OSPF, EIGRP, RIP, and IPX.
The Transport Layer:
The Transport layer is concerned with the establishment of network communication between two end points on the network, these can be either connection oriented or connectionless.
Data Term used at this Level:
Segment.
Network Devices/Protocols that operate at this level:
TCP, UDP and SPX.
The Session Layer:
Data Term used at this Level:
Data.
Network Protocols that operate at this level:
L2TP, PPTP, SCP, SIP, SDP, and PAP
The Presentation Layer:
Data Term used at this Level:
Data.
Protocols that operate at this level:
NDR, AFP, XDR and NCP.
The Application Layer:
Data Term used at this Level:
Data.
Network Devices/Protocols that operate at this level:
BitTorrent, HTTP, Telnet, SSH, SMB, NTP, BGP, FTP and TFTP.
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