Sem 2 Networking Programming Week 2 Protocols

Communications Fundamentals

• Networks vary in size and complexity, and a connection is not enough; devices must agree on "how" to communicate.
• A communication process involves a source (sender), destination (receiver), and a channel (media) that provides a path for communication.

Communication Protocols

• All communications are governed by protocols, which are rules that communications follow.
• Protocols vary depending on the type of communication.

Rule Establishment

• Individuals must use established rules or agreements to govern conversation.
• Protocols must account for:
  • Identified sender and receiver
  • Common language and grammar
  • Speed and timing of delivery
  • Confirmation or acknowledgment requirements

Network Protocol Requirements

• Common computer protocols must be in agreement and include:
  • Message encoding
  • Message formatting and encapsulation
  • Message size
  • Message timing
  • Message delivery options

Message Encoding

• Encoding is the process of converting information into another acceptable form for transmission.
• Decoding reverses this process to interpret the information.

Message Formatting and Encapsulation

• Messages are sent in a specific format or structure.
• Message formats depend on the type of message and the channel used to deliver the message.

Message Size

• Encoding between hosts must be in an appropriate format for the medium.
• Messages are converted to bits and encoded into a pattern of light, sound, or electrical impulses.

Message Timing

• Message timing includes:
  • Flow Control: manages the rate of data transmission and defines how much information can be sent and the speed at which it can be delivered.
  • Response Timeout: manages how long a device waits when it does not hear a reply from the destination.
  • Access Method: determines when someone can send a message.

Message Delivery Options

• Message delivery can be one of the following methods:
  • Unicast: one-to-one communication
  • Multicast: one-to-many, typically not all
  • Broadcast: one-to-all (not used in IPv6)

Protocol Suites

• Protocols must be able to work with other protocols.
• A protocol suite is a group of inter-related protocols necessary to perform a communication function.
• Protocol suites are viewed in terms of layers:
  • Higher Layers
  • Lower Layers (concerned with moving data and providing services to upper layers)

Evolution of Protocol Suites

• There are several protocol suites, including:
  • Internet Protocol Suite (TCP/IP)
  • Open Systems Interconnection (OSI) protocols
  • AppleTalk
  • Novell Netware

TCP/IP Protocol Example

• TCP/IP protocols operate at the application, transport, and internet layers.
• The most common network access layer LAN protocols are Ethernet and WLAN (wireless LAN).

TCP/IP Protocol Suite

• TCP/IP is the protocol suite used by the internet and includes many protocols.
• TCP/IP is an open standard protocol suite that is freely available to the public and can be used by any vendor.

TCP/IP Communication Process

• A web server encapsulates and sends a web page to a client.
• A client de-encapsulates the web page for the web browser.

Reference Models

The Benefits of Using a Layered Model

• Complex concepts such as how a network operates can be difficult to explain and understand.
• A layered model is used to simplify the explanation.
• Two layered models describe network operations:
  • Open System Interconnection (OSI) Reference Model
  • TCP/IP Reference Model

OSI and TCP/IP Model Comparison

• The OSI model divides the network access layer and the application layer of the TCP/IP model into multiple layers.
• The TCP/IP protocol suite does not specify which protocols to use when transmitting over a physical medium.

Data Encapsulation

Segmenting Messages

• Segmenting is the process of breaking up messages into smaller units.
• Multiplexing is the process of taking multiple streams of segmented data and interleaving them together.

Sequencing

• Sequencing messages is the process of numbering the segments so that the message may be reassembled at the destination.
• TCP is responsible for sequencing the individual segments.

Protocol Data Units (PDU)

• Encapsulation is the process where protocols add their information to the data.
• At each stage of the process, a PDU has a different name to reflect its new functions.

Encapsulation Example

• Encapsulation is a top-down process.
• The level above does its process and then passes it down to the next level of the model.

De-encapsulation Example

• Data is de-encapsulated as it moves up the stack.
• When a layer completes its process, that layer strips off its header and passes it up to the next level to be processed.

Data Access

Addresses

• Both the data link and network layers use addressing to deliver data from source to destination.
• Network layer source and destination addresses:
  • Responsible for delivering the IP packet from original source to the final destination.
  • Contain two parts:
    • Network portion (IPv4) or Prefix (IPv6)
    • Host portion (IPv4) or Interface ID (IPv6)

Layer 3 Logical Address

• The IP packet contains two IP addresses:
  • Source IP address
  • Destination IP address

Devices on the Same Network

• When devices are on the same network, the source and destination will have the same network portion of the address.

Role of the Data Link Layer Addresses: Same IP Network

• When devices are on the same Ethernet network, the data link frame will use the actual MAC address of the destination NIC.

Role of the Network Layer Addresses

• When the source and destination have a different network portion, this means they are on different networks.

Role of the Data Link Layer Addresses: Different IP Networks

• When the final destination is remote, Layer 3 will provide Layer 2 with the local default gateway IP address, also known as the router address.

Standards Organization

• Open standards encourage:
  • Interoperability
  • Competition
  • Innovation
  • Vendor-neutral
  • Non-profit organizations
  • Established to develop and promote the concept of open standards### Internet Governance
• Internet Architecture Board (IAB) manages and develops internet standards
• Internet Engineering Task Force (IETF) develops, updates, and maintains internet and TCP/IP technologies
• Internet Research Task Force (IRTF) focuses on long-term research related to internet and TCP/IP protocols

Standards Organizations

• Internet Corporation for Assigned Names and Numbers (ICANN) coordinates IP address allocation, domain name management, and assignment of other information
• Internet Assigned Numbers Authority (IANA) oversees and manages IP address allocation, domain name management, and protocol identifiers

Electronic and Communications Standards

Institute of Electrical and Electronics Engineers (IEEE)

• Creates standards in power and energy, healthcare, telecommunications, and networking

Electronic Industries Alliance (EIA)

• Develops standards relating to electrical wiring, connectors, and 19-inch racks for mounting networking equipment

Telecommunications Industry Association (TIA)

• Develops communication standards in radio equipment, cellular towers, Voice over IP (VoIP) devices, satellite communications, and more

International Telecommunications Union-Telecommunication Standardization Sector (ITU-T)

• Defines standards for video compression, Internet Protocol Television (IPTV), and broadband communications, such as digital subscriber line (DSL)

TCP/IP Model

• Consists of four layers: network (IP), datalink (Ethernet), physical

Network (IP) Layer

• Concerned with routing and addressing

Datalink (Ethernet) Layer

• Uses MAC (Media Access Control) addresses, e.g., 00:d9:w2:D9:p9:00

Physical Layer

• Deals with physical means of transmission, including cables, bits, and bytes

TCP/IP Overview

• TCP/IP is an open standard protocol suite that is freely available to the public and can be used by any vendor.
• TCP/IP is a standards-based protocol suite that is endorsed by the networking industry and approved by a standards organization to ensure interoperability.

TCP/IP Communication Process

• Web server encapsulation and sending a web page to a client.
• Client de-encapsulating the web page for the web browser.

Reference Models

The Benefits of Using a Layered Model

• Complex concepts such as how a network operates can be difficult to explain and understand, making a layered model useful.
• Two Layered models describe network Operations: OSI Reference Model and TCP/IP Reference Model.

OSI Model

• APPLICATION Layer: Contains protocols used for process-to-process communications.
• PRESENTATION Layer: Provides for common representation of the data transferred between application layer services.
• SESSION Layer: Provides services to the presentation layer and to manage data exchange.
• TRANSPORT Layer: Defines services to segment, transfer, and reassemble the data for individual communications.
• NETWORK Layer: Provides services to exchange the individual pieces of data over the network.
• DATA LINK Layer: Describes methods for exchanging data.
• PHYSICAL Layer: Describes the means to activate, maintain and de-activate physical connections.

IP Header

• A packet header is a "label" that provides information about the packet's contents, origin, and destination.

Message Size

• Encoding between hosts must be in an appropriate format for the medium.
• Messages sent across the network are converted to bits.
• Bits are encoded into a pattern of light, sound, or electrical impulses.
• The destination host must decode the signals to interpret the message.

Message Timing

• Flow Control: Manages the rate of data transmission and defines how much information can be sent and the speed at which it can be delivered.
• Response Timeout: Manages how long a device waits when it does not hear a reply from the destination.
• Access Method: Determines when someone can send a message.

Message Delivery Options

• Unicast: one-to-one communication.
• Multicast: one-to-many, typically not all.
• Broadcast: one-to-all (not an option for IPv6).

Network Protocol Overview

• Network protocols define a common set of rules.
• There will be a source (sender) and a destination (receiver).
• There will be a channel (media) that provides for the path of communications to occur.

Communication Protocols

• All communications are governed by protocols.
• Protocols are the rules that communications will follow.
• Protocols must account for the following requirements:
  • An identified sender and receiver.
  • Common language and grammar.
  • Speed and timing of delivery.
  • Confirmation or acknowledgment requirements.

Network Protocol Requirements

• Common computer protocols must be in agreement and include the following requirements:
  • Message encoding.
  • Message formatting and encapsulation.
  • Message size.
  • Message timing.
  • Message delivery options.

Message Encoding

• Encoding is the process of converting information into another acceptable form for transmission.
• Decoding reverses this process to interpret the information.

Message Formatting and Encapsulation

• When a message is sent, it must use a specific format or structure.
• Message formats depend on the type of message and the channel that is used to deliver the message.

TCP/IP Reference Model

• APPLICATION Layer: Represents data to the user, plus encoding and dialog control.
• TRANSPORT Layer: Supports communication between various devices across diverse networks.
• INTERNET Layer: Determines the best path through the network.
• NETWORK ACCESS Layer: Controls the hardware devices and media that make up the network.

OSI and TCP/IP Model Comparison

• The OSI model divides the network access layer and the application layer of the TCP/IP model into multiple layers.
• The TCP/IP protocol suite does not specify which protocols to use when transmitting over a physical medium.

Data Encapsulation

• Segmenting: the process of breaking up messages into smaller units.
• Multiplexing: the process of taking multiple streams of segmented data and interleaving them together.
• Increases speed: Large amounts of data can be sent over the network without tying up a communications link.
• Increases efficiency: Only segments which fail to reach the destination need to be retransmitted, not the entire data stream.