CCNA-1. Chapter2. Communicating over network

Communication methods common elements:

• sender
• reciever
• channel

Communication types:

• traditional computer data
• interactive voice
• video
• entertainment products

Segmentation (brake communication in to pieces)

• multiplexing (separate conversations can be transmitted together)
• increase the reliability of network communications
• added complexity

Local Area Network (LAN) - individual network usually administered by a single organization, spans a single geographical area, providing services and applications to people within a common organizational structure(business, campus, region). Wide Area Networks (WANs) - networks that connect LANs in geographically separated locations. Networking protocol suites (group of protocols that work cooperatively) describe:

• The format or structure of the message
• The method by which networking devices share information about pathways with other networks
• How and when error and system messages are passed between devices
• The setup and termination of data transfer sessions

Layered model:

• Assists in protocol design
• Fosters competition because products from different vendors can work together.
• Prevents technology or capability changes in one layer from affecting other layers above and below.
• Provides a common language to describe networking functions and capabilities.

Standards organizations that ratify networking protocols:

• Institute of Electrical and Electronics Engineers (IEEE)
• Internet Engineering Task Force (IETF)

Requests for Comments (RFCs) - publicly-available set of documents that contain specification of data communications protocols, resources that describe the use of the protocols, contain technical and organizational documents about the Internet, including the technical specifications and policy documents produced by the Internet Engineering Task Force (IETF). Protocol Data Unit (PDU) (the form that a piece of data takes at any layer) types:

• Data (The general term for the PDU used at the Application layer)
• Segment  (Transport Layer PDU)
• Packet (Internetwork Layer PDU)
• Frame (Network Access Layer PDU)
• Bits (PDU used when physically transmitting data over the medium)

TCP\IP model:

• Applicaton (represent data, encoding, diallog control)
• Transport (support communication of diverce devices across diverce networks)
• Internet (determine the best path through the network)
• Network Access (controls the hardware devices and media that make up the network)

OSI model (describes encoding, formatting, segmenting, encapsulating data for transmission over the network):

• Application (means for end-to-end connectivity between individuals)
  
  • Functions: Provide interfaces between applications
  • Protocols: DNS, HTTP, SMTP, Telnet, FTP, SMB
• Presentation (representation of data between the Application layers, standartization of data formats between systems)
  
  • Functions: Data coding and conversion for destination application interpretation, (de)compression, (de)encryption.
  • Protocols: QuickTime, MPEG, GIF, JPEG, TIFF.
• Session (provide services for Presentation of managing data exchange and diallogue organization)
  
  • Functions: Initiate dialogs, keep them active, restart idle\disrupted sessions
  • Protocols:NetBIOS
• Transport (manages the data transport between the processes running on each end host)
  
  • Functions: Conversation Multiplexing, segment/reassemble data, error recovery.
  • Protocols:TCP, UDP
• Network (specify the packet structure and processing used to carry the data from one host to another host.)
  
  • Functions: Address and route messages through an internetwork
  • Protocols: IP, IPX, AppleTalk
• Data Link (methods of exchanging data frames)
  
  • Function: Framing, MAC(data processing based on physical requirements, physical addressing), Error Detection
  • Protocols: Ethernet, PPP, HLDC, Frame Relay, ATM, GPRS
• Physical (mechanical, electrical,functional and procedural means to activate/maintain/deactivate physical connections)
  
  • Function: The physical components, Data encoding, Signaling
  • Protocols: Ethernet, Bluetooth, WiFI