Module 3 - Protocols and Models Flashcards
Role of Protocols
In addition to identifying the source and destination, computer and network protocols define the details of how a message is transmitted across a network. Common computer protocols include the following requirements:
Message encoding
Message formatting and encapsulation
Message size
Message timing
Message delivery options
Encoding / Decoding
Encoding is the process of converting information into another acceptable form, for transmission. Decoding reverses this process to interpret the information.
Flow Control
This is the process of managing the rate of data transmission. Flow control defines how much information can be sent and the speed at which it can be delivered. For example, if one person speaks too quickly, it may be difficult for the receiver to hear and understand the message. In network communication, there are network protocols used by the source and destination devices to negotiate and manage the flow of information.
Response Timeout
Hosts on the network use protocols that spedify how long to wait for responses and what action to take if a respoinse timeout occurds
Access method
When a device wants to transmit on a particular medium, the NIC determines whether the medium s available.
Which step of the communication process is concerned with properly identifying the address of the sender and receiver?
Formatting
Network Communications Protocols
Protocols enable two or more devices to communicate over one or more networks. The Ethernet family of technologies involves a variety of protocols such as IP, Transmission Control Protocol (TCP), HyperText Transfer Protocol (HTTP), and many more.
Network Security Protocols
Protocols secure data to provide authentication, data integrity, and data encryption. Examples of secure protocols include Secure Shell (SSH), Secure Sockets Layer (SSL), and Transport Layer Security (TLS).
Routing Protocols
Protocols enable routers to exchange route information, compare path information, and then to select the best path to the destination network. Examples of routing protocols include Open Shortest Path First (OSPF) and Border Gateway Protocol (BGP).
Service Discovery Protocols
Protocols are used for the automatic detection of devices or services. Examples of service discovery protocols include Dynamic Host Configuration Protocol (DHCP) which discovers services for IP address allocation, and Domain Name System (DNS) which is used to perform name-to-IP address translation.
Network Protocol Functions
Addressing, Reliability, Flow control, Sequencing, Error Detection, Application Interface
Addressing
This identifies the sender and the intended receiver of the message using a defined addressing scheme. Examples of protocols that provide addressing include Ethernet, IPv4, and IPv6.
Reliability
This function provides guaranteed delivery mechanisms in case messages are lost or corrupted in transit. TCP provides guaranteed delivery.
Flow control
This function ensures that data flows at an efficient rate between two communicating devices. TCP provides flow control services.
Sequencing
This function uniquely labels each transmitted segment of data. The receiving device uses the sequencing information to reassemble the information correctly. This is useful if the data segments are lost, delayed or received out-of-order. TCP provides sequencing services.
Error Detection
This function is used to determine if data became corrupted during transmission. Various protocols that provide error detection include Ethernet, IPv4, IPv6, and TCP.
Application Interface
This function contains information used for process-to-process communications between network applications. For example, when accessing a web page, HTTP or HTTPS protocols are used to communicate between the client and server web processes.
DHCPv4
Dynamic Host Configuration Protocol for IPv4. A DHCPv4 server dynamically assigns IPv4 addressing information to DHCPv4 clients at start-up and allows the addresses to be re-used when no longer needed.
DHCPv6
Dynamic Host Configuration Protocol for IPv6. DHCPv6 is similar to DHCPv4. A DHCPv6 server dynamically assigns IPv6 addressing information to DHCPv6 clients at start-up.
SLAAC
Stateless Address Autoconfiguration. A method that allows a device to obtain its IPv6 addressing information without using a DHCPv6 server
DNS
Domain Name System. Translates domain names such as cisco.com, into IP addresses.
SMTP
Simple Mail Transfer Protocol. Enables clients to send email to a mail server and enables servers to send email to other servers.
POP3
Post Office Protocol version 3. Enables clients to retrieve email from a mail server and download the email to the client’s local mail application.
IMAP
Internet Message Access Protocol. Enables clients to access email stored on a mail server as well as maintaining email on the server.
FTP
File Transfer Protocol. Sets the rules that enable a user on one host to access and transfer files to and from another host over a network. FTP is a reliable, connection-oriented, and acknowledged file delivery protocol.
SFTP
SSH File Transfer Protocol. As an extension to Secure Shell (SSH) protocol, SFTP can be used to establish a secure file transfer session in which the file transfer is encrypted. SSH is a method for secure remote login that is typically used for accessing the command line of a device.
TFTP
Trivial File Transfer Protocol. A simple, connectionless file transfer protocol with best-effort, unacknowledged file delivery. It uses less overhead than FTP.
HTTP
Hypertext Transfer Protocol. A set of rules for exchanging text, graphic images, sound, video, and other multimedia files on the World Wide Web.
HTTPS
HTTP Secure. A secure form of HTTP that encrypts the data that is exchanged over the World Wide Web.
REST
Representational State Transfer. A web service that uses application programming interfaces (APIs) and HTTP requests to create web applications.
TCP
Transmission Control Protocol. Enables reliable communication between processes running on separate hosts and provides reliable, acknowledged transmissions that confirm successful delivery.
UDP
User Datagram Protocol. Enables a process running on one host to send packets to a process running on another host. However, UDP does not confirm successful datagram transmission.
IPv4
Internet Protocol version 4. Receives message segments from the transport layer, packages messages into packets, and addresses packets for end-to-end delivery over a network. IPv4 uses a 32-bit address.
IPv6
IPv6 - IP version 6. Similar to IPv4 but uses a 128-bit address.
NAT
NAT - Network Address Translation. Translates IPv4 addresses from a private network into globally unique public IPv4 addresses.
ICMPv4
ICMPv4 - Internet Control Message Protocol for IPv4. Provides feedback from a destination host to a source host about errors in packet delivery.
ICMPv6
ICMPv6 - ICMP for IPv6. Similar functionality to ICMPv4 but is used for IPv6 packets.
ICMPv6 ND
ICMPv6 ND - ICMPv6 Neighbor Discovery. Includes four protocol messages that are used for address resolution and duplicate address detection.
OSPF
OSPF - Open Shortest Path First. Link-state routing protocol that uses a hierarchical design based on areas. OSPF is an open standard interior routing protocol.
EIGRP
EIGRP - Enhanced Interior Gateway Routing Protocol. An open standard routing protocol developed by Cisco that uses a composite metric based on bandwidth, delay, load and reliability.
BGP
BGP - Border Gateway Protocol. An open standard exterior gateway routing protocol used between Internet Service Providers (ISPs). BGP is also commonly used between ISPs and their large private clients to exchange routing information.
ARP
ARP - Address Resolution Protocol. Provides dynamic address mapping between an IPv4 address and a hardware address.
Ethernet
Ethernet - Defines the rules for wiring and signaling standards of the network access layer.
WLAN
WLAN - Wireless Local Area Network. Defines the rules for wireless signaling across the 2.4 GHz and 5 GHz radio frequencies.
Application Layer
Name System
Host Config
Email
File Transfer
Web and Web Services
Transport Layer
TCP (Connection Control)
UDP (Connectionless)
Internet Layer
Internet Protocol
Messaging
Routing Protocols
Network Access Layer
Address Resolution (ARP)
Data Link Protocols (Ethernet, WLAN)
Internet Society (Isoc)
Responsible for Promoting the open development and evolution of internet use throughout the world.
Internet Architecture Board (IAB)
Responsible for the overall management and development of internet standards.
Internet Engineering Trask Force (IETF)
Develops updates, and maintains internet and TCP/IP technologies. This includes the process and documents for developng new protocols and updating existing ones. Request for Comments documents.
Internet Research Task Force (IRTF)
Focused on long-term research related to internet and TCP/IP protoclols such as Antti-Spam Research Group (ASRG), Crypto Forum Research Group (CFRG), and Peer-to-Peer Research Group (P2PRG)
Internet Corporation for Assigned Names and Numbers (ICANN)
coordinates IP address allocation, the management of domain names, and the assignment of other information used in
Institute of Electrical and Electronics Engineers
Organization of electrical engineering and electronics dedicated. to advancing technological innovation and creating standards in a wide area of industries including power and energy, healthcare, telecommunications, and networking.
Electronic Industries Alliance (EIA)
Organization is best known for its standards relating to electrical wiring, connectors, and the 19-inch racks used to mount networking equipment.
Telecommunications Industry Association (TIA)
Organization responsible for developing communication standards in a variety of areas including radio equipment, cellular towers, Voice over IP (VoIP) devices, satellite communications, and more.
International Telecommunications Union-Telecommunication Standardization Sector (ITU-T)
One of the largest and oldest communication standards organizations. The ITU-T defines standards for video compression, Internet Protocol Television (IPTV), and broadband communications, such as a digital subscriber line (DSL).
Open System Interconnection (OSI) Reference Model
Application
Presentation
Session
Transport
Network
Data Link
Physical
TCP/IP Reference Model
Application
Transport
Internet
Network Access
7 - Application
The application layer contains protocols used for process-to-process communications.
6 - Presentation
The presentation layer provides for common representation of the data transferred between application layer services.
5 - Session
The session layer provides services to the presentation layer to organize its dialogue and to manage data exchange.
4 - Transport
The transport layer defines services to segment, transfer, and reassemble the data for individual communications between the end devices.
3 - Network
The network layer provides services to exchange the individual pieces of data over the network between identified end devices.
2 - Data Link
The data link layer protocols describe methods for exchanging data frames between devices over a common media
1 - Physical
The physical layer protocols describe the mechanical, electrical, functional, and procedural means to activate, maintain, and de-activate physical connections for a bit transmission to and from a network device.
TCP/IP Model
TCP/IP Model Layer Description
4 - Application Represents data to the user, plus encoding and dialog control.
3 - Transport Supports communication between various devices across diverse networks.
2 - Internet Determines the best path through the network.
1 - Network Access Controls the hardware devices and media that make up the network.
Segmenting Benefits
Increases speed - Because a large data stream is segmented into packets, large amounts of data can be sent over the network without tying up a communications link. This allows many different conversations to be interleaved on the network called multiplexing.
Increases efficiency -If a single segment is fails to reach its destination due to a failure in the network or network congestion, only that segment needs to be retransmitted instead of resending the entire data stream.
Data Encapsulation
Data, Segment, Packet, Frame, Bits
Data - General term for any PDU used at the application layer
Segment - Transport layer PDU
Packet - Network Layer PDU
Frame - Data link layer pdu
Bits - physical layer PDU used when physically transmitting over the medium
Segmentation
Segmentation is the process of dividing a stream of data into smaller units for transmissions over the network. Segmentation is necessary because data networks use the TCP/IP protocol suite send data in individual IP packets. Each packet is sent separately, similar to sending a long letter as a series of individual postcards. Packets containing segments for the same destination can be sent over different paths.
Sequencing
In network communications, each segment of the message must go through a similar process to ensure that it gets to the correct destination and can be reassembled into the content of the original message, as shown in the figure. TCP is responsible for sequencing the individual segments.
Source IP address
The IP address of the sending device, which is the original source of the packet.
Destination IP Address
The IP address of the receiving device, which is the final destination of the packet.
Network portion (IPv4) or Prefix (IPv6)
Network portion (IPv4) or Prefix (IPv6) - The left-most part of the address that indicates the network in which the IP address is a member. All devices on the same network will have the same network portion of the address.
Host portion (IPv4) or Interface ID (IPv6)
Host portion (IPv4) or Interface ID (IPv6) - The remaining part of the address that identifies a specific device on the network. This portion is unique for each device or interface on the network.
Subnet Mask / Prefix Length
The subnet mask (IPv4) or prefix-length (IPv6) is used to identify the network portion of an IP address from the host portion.
Source MAC address
This is the data link address, or the Ethernet MAC address, of the device that sends the data link frame with the encapsulated IP packet. The MAC address of the Ethernet NIC of PC1 is AA-AA-AA-AA-AA-AA, written in hexadecimal notation.
Destination MAC address
When the receiving device is on the same network as the sending device, this is the data link address of the receiving device. In this example, the destination MAC address is the MAC address of the FTP server: CC-CC-CC-CC-CC-CC, written in hexadecimal notation
Which layer of the OSI model defines services to segment and reassemble data for individual communications between end devices?
Transport
