OSI/TCP Model

Question 1

Layer 1: Physical (Network Interface TCP 1)

Answer 1

• BITS
• media signal and binary information
• provides the electrical and mechanical connections to the network
• PHYSICAL STRUCTURE (cables, hubs, etc)
• NIC card operates
• data encoding, physical medium attachment, transmission technique, baseband
  or broadband physical medium transmission bits and volts

PROTOCOLS:
Hub, RS-232, RJ45, V.34, 100BASE-TX, SDH, DSL, 802.11

Question 2

Layer 2: Data Link (Network Interface TCP 1)

Answer 2

• FRAMES
• MAC and LLC - physical addressing
• provides the flow of data for MAC addresses
• FRAMES (envelopes, contains MAC address)
• establishes and terminates the logical link between nodes, frame traffic control, frame sequencing, frame acknowledgement, frame delimiting, frame error checking, medial access control

PROTOCOLS:
Switch Bridge, WAP, PPP, SLIP, Ethernet 802.11, MAC/LLC,
VLAN, ATM, HDP, Fibre Channel Frame Relay, HDLC, Q.921, Token Ring

Question 3

Layer 3: Network (Internet TCP 2)

Answer 3

• PACKETS
• path determination and logical addressing
• provides routing decisions based on IP, IPX
• PACKETS (“letter”, contains IP address
• routing, subnet traffic control, frame fragmentation, logical physical address
  mapping, subnet usage accounting

PROTOCOLS: Routers - IP Sec, ICMP, IGMP, OSPF

Question 4

Layer 4: Transport (Transport TCP 3)

Answer 4

• SEGMENTS
• end to end connections and reliability
• ensures error-free packets
• TCP, HOST TO HOST, FLOW CONTROL
• message segmentation, message acknowledgement, message traffic control,
  session multiplexing

PROTOCOLS:
TCP, UDP, SCTP, SSL, TLS

Question 5

Layer 5: Session (Application TCP 4)

Answer 5

• DATA
• inter host communication
• establishes, manages, and terminates NFS, SQL sessions
• SYNC & SEND TO PORTS (logical ports)
• session establishment, maintenance and termination, session support -
  performance security, name recognition, logging, etc

PROTOCOLS:
RPC, SQL, NFA

Question 6

Layer 6: Presentation (Application TCP 4)

Answer 6

• DATA
• data compression and encryption
• ensures protocol conversion, data translation, ACSII, JPE
• SYNTAX LAYER
• character code translation, data conversion, data compression, data encryption,
  character set translation

PROTOCOLS:
HTML, DOC, JPEG,
MP3, AVI

Question 7

Layer 7: Application (Application TCP 4)

Answer 7

• DATA
• Network process to application
• Facilitates communication between software applications, like Outlook/IE
• Support for applications HTTP, FTP, SMTP (email)
• END USER LAYER
• Resource sharing, remote file access, remote printer access, directory services,
  network management

PROTOCOLS:
DNS, WWWW/HTTP, P2P, EMAIL/POP, SMTP, Telnet, FTP