3. Protocols and Models

3. Protocols and Models

1. 3.1. The Rules

   • Communications Fundamentals
     • Sender: Message source
     • Receiver: Message Destination
     • Channel: Media that provides the pathway over which the message travels from source to destination
   • Communication Protocols (and Delivery Options)
     • Analogy: Face-to-face communicating
     • Network: Devices communicating
   • Rule Establishment
     • An identified sender and receiver
     • Common language and grammar
     • Speed and timing of delivery
     • Confirmation or acknowledgment requirements
   • Network Protocol Requiriments
     • Message Encoding
       • Process of converting information into another acceptable form, for transmission
     • Message formating and encapsulation
       • It must used a specific format or structure. Message formats depend on the type of message and the channel that is used to deliver the message.
     • Message Size
       • The size of the message
     • Message Timming
       • Flow Control: Process of managing the rate of data transmission
       • Response Timeout: Time of waiting a response within an acceptable amount of time
       • Access method: Determines when someone can send a message

2. 3.2. Protocols

   • Overview
     • Define a common format and set of rules for exchanging messages between devices.
       • Network Communications Protocols: enable two or more devices to communicate over one or more networks.
       • Network Security Protocols: Protocols secure data to provide authentication, data integrity, and data encryption
       • Routing Protocols: Protocols enable routers to exchange route information, compare path information, and then to select the best path to the destination network
       • Service Discovery Protocols: used for the automatic detection of devices or services
   • Functions
     • Addressing: Identifies the sender and the intended receiver of the message using a defined addressing scheme
     • Reliability: Provides guaranteed delivery mechanisms in case messages are lost or corrupted in transit
     • Flow control: Ensures that data flows at an efficient rate between two communicating devices
     • Sequencing: uniquely labels each transmitted segment of data
     • Error Detection: Is used to determine if data became corrupted during transmission
     • Application Interface: Contains information used for process-to-process communications between network applications
   • Interaction

3. 3.3. Protocol Suites

   • Group of inter-related protocols necessary to perform a communication function, are sets of rules that work together to help solve a problem
   • Evolution
     • TCP/IP: Most common today
     • OSI Protocols: Developed in 1977, categorizes the functions of the protocols
     • AppleTalk: Short-lived protocol suite released by Apple Inc. in 1985
     • Novell NetWare: Short-lived propietary protocolsuite and network OS developed by Novell Inc in 1983
   • TCP/IP Protocol
     • TCP/IP protocols are available for the application, transport, and internet layers. There are no TCP/IP protocols in the network access layer
     • Suite
       • Includes many protocols and continues to evolve to support new services
         • Standards-based protocol suite: Endorsed by the networking indutry and approved by a standards organization
         • Open Standard Protocol Suite: Freedly available to the public and can be used by any vendor

4. 3.4. Standards Organizations

   • Open
     • Encourage interoperability, competition, and innovation, they guarantee that the product of no single company can monopolize the market or have an unfair advantage.
       • They are usually vendor-neutral, non-profit organizations established to develop and promote the concept of open standards
   • Internet
     • Various organizations have different responsibilities for promoting and creating standards for the internet and TCP/IP protocol.
     • They are also standards organizations involved with the development and support of TCP/IP
       • IANA
       • ICANN
   • Electronical and Communicational
     • Other standards organizations have responsibilities for promoting and creating the electronic and communication standards used to deliver the IP packets as electronic signals
       • IEEE
       • EIA
       • TIA
       • ITU-T

5. 3.5. Reference Models

   • Layered Model
     • It´s used to modularize the operations of a network into manageable layers.
       • OSI Reference Model
         • Provides an extensive list of functions and services that can occur at each layer
       • TCP/IP Protocol Model
         • Describes the functions that occur at each layer of protocols within the TCP/IP suite

6. 3.6. Data Encapsulation

   • Segmenting Messages
     • Process of dividing a stream of data into smaller units for transmissions over the network
       • It´s necessary because data networks use the TCP/IP protocol suite send data in individual IP packets
   • Sequencing
     • Each segment of the message must go through a particular process to ensure that it gets to the correct destination and can be reassembled into the content of the original message.
       • TCP is responsible for sequencing the individual segments.
   • Protocol Data Units
     • Data
     • Segment
     • Packet
     • Frame
     • Bits
   • Encapsulation
   • De-encapsulation

7. 3.7. Data Access

   • Addresses
     • Network layer source and destination addresses: Responsible for delivering the IP packet from the original source to the final destination
     • Data link layer source and destination addresses: Responsible for delivering the data link frame from one network interface card (NIC) to another NIC on the same network.
   • Layer 3 Logical Address
     • IP Packet
       • Source IP address
       • Source IP address
     • IP Address
       • Network portion (IPv4) or Prefix (IPv6): Indicates the network in which the IP address is a member
       • Host portion (IPv4) or Interface ID (IPv6) : Identifies a specific device on the network.
   • Devices on...
     • The Same Network
       • The network portion of the source IPv4 address and the network portion of the destination IPv4 address are the same
     • A Remote Network
       • The network portion of the source IPv4 address and the network portion of the destination IPv4 address are different
   • Role of the Data Link Layer Address
     • Same IP Network
       • When the sender and receiver of the IP packet are on the same network, the data link frame is sent directly to the receiving device.
     • Different IP Networks
       • The Ethernet data link frame cannot be sent directly to the destination host because the host is not directly reachable in the network of the sender.
         • The Ethernet frame must be sent to another device known as the router or default gateway.
     • On an Ethernet network, the data link addresses are known as Ethernet Media Access Control (MAC)
       • Source
       • Destination
   • Role of the Network Layer Addresses
     • When the sender of the packet is on a different network from the receiver, the source and destination IP addresses will represent hosts on different networks
       • This will be indicated by the network portion of the IP address of the destination host
   • Data Link Adresses
     • Deliver the data link frame from one network interface to another network interface on the same network.
       • Router to Router
       • Router to Server

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