Open Systems Interconnection 7 – Layer

Open Systems Interconnection (OSI)
• Created by the International Organization for Standardization (ISO) in 1984
• Model asitektur for interkomputer communications.
• Explain how the information from the application software on one computer and then move through the medium until it is received back by the application software on a second computer.
7-Layer OSI Model Layer TCP / IP
- Application
- Presentation - Application
- Session
- Transport - Transport
- Network - Internet
- Data Link - Network
- Physical interface physical
Layer 1
Physical
• Bit
- Media communications (copper cable, fiber, air)
- Signal processing (representation logic 0 / 1, the transfer speed, etc..)
• Network components
- Repeater
- Multiplexer
- Hubs (Passive and Active)
- TDR
- Oscilloscope
- Amplifier
• Protocols
- IEEE 802 (Ethernet standard)
- IEEE 802.2 (Ethernet standard)
- ISO 2110
- ISDN

Layer2
Data link
• Frame - The process of framing by giving marks the start and end of frame - Checksum error detection, CRC - The wrong frame can be discarded or diretransmisi
• Network components
- Bridge
- Switch
- ISDN Router
- Intelligent Hub
- NIC
- Advanced Cable Tester
• Protocols
- Media Access Control
Layer 3
 
Network 

• Packets
- Packet routing, flow control, error control
• Challenges of path finding
- Network heterogeneity
• eg, from Ethernet to Token Ring to FDDI
- Multi-hop
• A data packet may need to go through several hops before reaching the destination
- Multi-path
• The shortest route is not always the best route
• How big is the problem caused by the delay provided by the route
• Network components
- Bridge
- Switch
- ISDN Router
- Intelligent Hub
- NIC
- Advanced Cable Tester
• Protocols
- IP; ARP; RARP, ICMP; RIP; OSFP;
- IGMP;
- IPX
- NWLink
- NetBEUI
- OSI  
- DDP
- DECnet
Layer 4

Transport 

• RFC 892 • Segment - Accuracy of data transfer, data recovery, flow control • Flow control - Dividing the data into packets and mark each package with serial number - Error detection and correction • Network components - Gateway - Advanced Cable Tester - Brouter
• Protocols
- TCP, ARP, RARP;
- SPX
- NWLink
- NetBIOS / NetBEUI
- ATP

Layer 5
Session
    • Data     • Mechanisms to manage the process of end-user applications: half / full duplex, check-pointing,  
      adjournment, termination, and restart procedures
    • Network components        - Gateway     • Protocols       - NetBIOS       - Names Pipes       - Mail Slots       - RPC
Layer 6
Presentation
    • Data representation and conversion
            ex: EBCDIC -> ASCII     • Data compression / decompression     • Network components         - Gateway         - Redirector     • Protocols
       - None
Layer 7
Application
    • Data Interpretation
    • Encryption / decryption
    • Network components
        - Gateway
    • Protocols
       - Control; FTP
       - TFTP; BOOTP
       - SNMP; rlogin
       - SMTP; MIME;
       - NFS; FINGER
       - TELNET; NCP
       - APPC; AFP
       - SMB