Protocols and Models
Data Link Addresses
- Are layer 2 physical addresses. -The purpose of the data link address is to deliver the data link from from one network interface to another network interface on the SAME network. (Can't send a packet to a device that doesn't have an ethernet cord connected to it) -- its NIC to NIC - Before an IP packet can be sent over a wired or wireless network, it must be encapsulated in a data link frame, so it can be transmitted over the physical medium. As the IP packet travels from host-to-router, router-to-router etc..... the IP packet is encapsulated in a new data link frame.
Internet Society (ISOC)
-Internet standard organization -Responsible for promoting the open development and evolution of internet use throughout the world
Layer 3 Logical Address
-Is an IP address IP address is the network layer, or Layer 3, logical address used to deliver the IP packet from the original source to the final destination
Protocol Data Units (PDUs)
-Is the form that a piece of data takes at any layer. -As application data is passed down the protocol stack on its way to be transmitted across the network media, various protocol information is added at each level -Each Succeeding layer encapsulates the PDU that it receives from the layer above in accordance with the protocol being used. -At each stage of the process, a PDU has a different name to reflect its new functions -There is no universal naming conventions for PDUs See figure for PDU names at each level: Data - the general term for the 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 data over the medium If the Transport header is TCP, then it is a segment. If the Transport header is UDP then it is a datagram
What are 3 elements of message timing?
1. Flow control 2. Response Timeout 3. Access method
What are the 4 different types of network protocols?
1. Network Communications Protocols 2. Network security protocols 3. Routing protocols 4. Service Discovery Protocols
Which step of the communication process is concerned with properly identifying the address of the sender and receiver? A: Formatting B: Encoding C: Encapsulation
A: Formatting
Which protocol stack layer encapsulates data into frames? A: data link B: transport C: network D: application
A: data link
What layers are used when sending packets between the web browser of a host and a webserver? And What are their protocols in each layer?
Application - HTTP Transport - TCP Internet - Internet Protocol Network Access - Ethernet
What is the process of converting information into the proper form for transmission? A: Formatting B: Encoding C: Encapsulation
B: Encoding
Internet Corporation for Assigned Names and Numbers (ICANN)
Based in the U.S., ICANN coordinates IP address allocation, the management of domain names, and assignment of other information used in TCP/IP protocols.
Which of the following are protocols that provide feedback from the destination host to the source host regarding errors in packet delivery? (Choose two.) A: IPv4 B: TCP C: ICMPv4 D: IPv6 E: UDP F: ICMPv6
C: ICMPv4 F: ICMPv6
What is the order of the two addresses in the data link frame? A: source MAC, destination MAC B: destination MAC, source IP C: destination IP, source IP D: destination MAC, source MAC E: source IP, destination IP
D: destination MAC, source MAC
Internet Engineering Task Force (IETF)
Develops, updates, and maintains Internet and TCP/IP technologies. This includes the process and documents for developing new protocols and updating existing protocols known as Request for Comments (RFC) documents.
Message Formatting and Encapsulation
Encapsulation -- is the process of placing one message format in side another De-encapsulation -- occurs when the process is reversed by the recipient and the letter is removed from the envelope In the picture, the fields of the IPv6 packet identify the the source of the packet and its destination. IP is responsible for sending a message from the message source to destination over one or more networks. Formatting -- is concerned with properly identifying the address of the sender and receiver.
Internet Research Task Force (IRTF)
Focused on long-term research related to Internet and TCP/IP protocols such as Anti-Spam Research Group (ASRG), Crypto Forum Research Group (CFRG), and Peer-to-Peer Research Group (P2PRG).
Hyper Text Transfer Protocol (HTTP)
Governs the way a webserver and a web client interact. HTTP defines the content and formatting of the requests and responses that are exchanged between the client and server. Both the client and webserver implement HTTP as part of the application. HTTP relies on other protocols to govern how the messages are transported between the client and server.
What is Response Timeout?
If a person asks a question and does not hear a response within an acceptable amount of time, the person assumes that no answer is coming and reacts accordingly. The person may repeat the question or instead, may go on with the conversation. Hosts on the network use network protocols that specify how long to wait for responses and what action to take if a response timeout occurs.
The 3 different types of broadcasting using Node Icon representation.
In note icon representation, Nodes are typically representing as a Circle.
What is Multicast?
Information is being transmitted to a one or more end devices.
What is Broadcast?
Information is being transmitted to all end devices.
Message Encoding
Is the process of converting information into another acceptable form, for transmission. --Decoding reverses this process to interpret the information 1. Messages are first converted into bits by the sending host. 2. Each bit is encoded into a pattern of voltage voltages on copper wires, infrared light in optical fibers, or microwaves for wireless systems. 3. The destination host receives and decodes the signals to interpret the message
Ethernet Media Access Control address (MAC addresses)
MAC addresses are physically embedded on the Ethernet NIC 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. 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. See figure: The MAC address of the Ethernet NIC of PC1 is AA-AA-AA-AA-AA-AA, written in hexadecimal notation. 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.
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.
TCP/IP Protocol Suite
See Pic
Destination IP address
The IP address of the receiving device, which is the final destination of the packet.
Source IP address
The IP address of the sending device, which is the original source of the packet
OSI Reference Model
The OSI reference model provides an extensive list of functions and services that can occur at each layer. This type of model provides consistency within all types of network protocols and services by describing what must be done at a particular layer, but not prescribing how it should be accomplished.
What what does the Message Destination (receiver) do?
The destination receives the message and interprets it.
What does Channel consist of?
This consists of the media that provides the pathway over which the message travels from source to destination. A channel could be a verbal language or a written language.
What is Access Method?
This determines when someone can send a message. When a device wants to transmit on a wireless LAN, it is necessary for the WLAN network interface card (NIC) to determine whether the wireless medium is available.
What is 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.
What does message format depend on?
depends on the type of message and the channel that is used to deliver the message.
Sequencing
iIs "numbering" the packets so they can be re-assembled correctly - this is incase they get send out of order -TCP is responsible for sequencing the individual segments
What is a Protocol Suite
is a group of inter-related protocols necessary to perform a communication function A protocol suite is a set of protocols that work together to provide comprehensive network communication services.
What is the network access layer responsible for?
it is responsible for delivering IP packet(s) over the physical medium.
What is segmentation?
-Is the process of dividing a stream of data into smaller unity for transmissions over the network. -is necessary because data networks use the TCP/IP protocol suite to 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
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. -The subnet mask (IPv4) or prefix-length (IPv6) is used to identify the network portion of an IP address from the host portion. IE Different networks Source: 192.168.1.110 Destination: 172.16.1.99 Same networks Source: 192.168.1.25 Destination: 192.168.1.28
Open Standards
-They encourage interoperability, competition, and innovation. -Open standards Also guarantee that the product of no signal company can monopolize the market or have an unfair advantage over its competition. IE All home routers incorporate standard protocols such as: IPv4, IPv6, DHCP, SLAAC, Ethernet, and 802.11 Wireless LAN
TCP IP Protocol Model
-Was created in the early 1970s -AKA Internet Model -This model closely matches the structure of a particular protocol suite. -TCP/IP model is a protocol model because it describes the functions that occur at each layer of protocols within the TCP/IP suite -Is used as a reference model
What are the functions of network procols?
1. 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. 2. Reliability - This function provides guaranteed delivery mechanisms in case messages are lost or corrupted in transit. TCP provides guaranteed delivery. 3. Flow control - This function ensures that data flows at an efficient rate between two communicating devices. TCP provides flow control services. 4. 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. 5. 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. 6. 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.
What are the benefits of using a layered model to describe network protocols and operations?
1. Assisting in protocol design because protocols that operate at a specific layer have defined information that they act upon and a defined interface to the layers above and below 2. Fostering competition because products from different vendors can work together 3. Preventing technology or capability changes in one layer from affecting other layers above and below 4. Providing a common language to describe networking functions and capabilities
What protocols are involved when a client sends a request to a web server for its web page?
1. HTTP 2. TCP 3. IP 4. Ethernet
What are 2 primary benefits to segmenting messages?
1. Increased 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. 2. Increased 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.
Electronic and Communication Standards Organizations
1. Institute of Electrical and Electronics Engineers (IEEE, pronounced "I- 2. Electronic Industries Alliance (EIA) 3. Telecommunications Industry Association (TIA) 4. International Telecommunications Union-Telecommunication Standardization Sector (ITU-T)
Which 2 organizations are involved with the development and support of TCP/IP
1. Internet Corporation for Assigned Names and Numbers (ICANN) 2. Internet Assigned Numbers Authority (IANA)
Internet Standards Organizations
1. Internet Society (ISOC) 2. Internet Architecture Board (IAB) 3. Internet Engineering Taskforce (IETF) -Internet Engineering Steering Group (IESG) >Working group 1 and working group 2 4. Internet Research Task Force (IRTF) -Internet Research Steering Group (IRSG) >Research group 1 and research group 2
What are the 3 elements that all communication systems have in common?
1. Message Source (sender) 2. Message Destination (receiver) 3. Channel
What are the requirements of common computer protocols?
1. Message encodeing 2. Message formatting and encapsulation 3. Message Size 4. Message Timing 5. Message delivery options
What are the two layered models that are used to describe network operations?
1. Open System Interconnection (OSI) Reference Model 2. TCP/IP Reference Model
TCP/IP Protocol Layers and Descriptions
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. ------------- (See Figure) At the network access layer, the TCP/IP protocol suite does not specify which protocols to use when transmitting over a physical medium; it only describes the handoff from the internet layer to the physical network protocols. OSI Layers 1 and 2 discuss the necessary procedures to access the media and the physical means to send data over a network. The network access layer and the application layer of the TCP/IP model are further divided to describe discrete functions that must occur at these layer
Open System Interconnection (OSI) Model Layers
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.
Routing Protocols
Are protocols that 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).
Network Communications Protocols
Are protocols that 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
Are protocols that 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).
A web client is sending a request for a webpage to a web server. From the perspective of the client, what is the correct order of the protocol stack that is used to prepare the request for transmission? A: HTTP, IP, TCP, Ethernet B: HTTP, TCP, IP, Ethernet C: Ethernet, TCP, IP, HTTP D: Ethernet, IP, TCP, HTTP
B: HTTP, TCP, IP, Ethernet Topic 3.3.0 - 1. HTTP governs the way that a web server and client interact.2. TCP manages individual conversations between web servers and clients.3. IP is responsible for delivery across the best path to the destination.4. Ethernet takes the packet from IP and formats it for transmission.
Standard Organizations
Because there are many different manufacturers of network components, they must all use the same standards. In networking standards are developed by international standards organizations. Standard organizations are usually non-profit organizations established to develop and promote the concept of open standards These organizations are important in maintaining an open internet with freely accessible specifications and protocols that can be implemented by any vendor. A standards organization may draft a set of rules entirely on its own or, in other cases, may select a proprietary protocol as the basis for the standard. If a proprietary protocol is used, it usually involves the vendor who created the protocol.
A device receives a data link frame with data and processes and removes the Ethernet information. What information would be the next to be processed by the receiving device? A: HTTP at the application layer B: HTML at the application layer C: IP at the internet Layer D: UDP at the internet layer E: TCP at the transport layer
C: IP at the internet Layer De-encapsulation goes: 1. Ethernet (network access layer) 2. IP (Internet Layer) 3. TCP (Transport layer) 4. Data (Application Layer) Encapsulation goes: 1. Data (Application Layer) 2. TCP (Transport layer) 3. IP (Internet Layer) 4. Ethernet (network access layer)
What is the general term that is used to describe a piece of data at any layer of a networking model? A: frame B: packet C: protocol data unit (PDU) D: segment
C: protocol data unit (PDU) Topic 3.6.0 - The term protocol data unit (PDU) is used to describe a piece of data at any layer of a networking model. A packet is the PDU at the network layer. A frame is the data link layer PDU. A segment is the PDU at the transport layer.
What are the most common network access layer LAN protocols?
Ethernet, WLAN protocols
What is Unicast?
Information is being transmitted to a single end device.
What are some network protocol suites that were competing during the creation of networking?
Internet Protocol Suite or TCP/IP - is the most common and relavent protocol used today. - is an open standard protocol suite maintained by the Internet Engineering Task Force (IETF) Open Systems Interconnection (OSI) Protocols -is a family of protocols developed jointly in 1977 by the International Organization of Standardization (ISO) and the International Telecommunications Union (ITU) -included a seven-layer model called the OSI reference model -OSI model categorizes the functions of its protocols -OSI protocols have largely been replaced by TCP/IP Apple Talk -A short-lived proprietary protocol suite released by Apple Inc. in 1985 for Apple devices. -In 1995, Apple adopted TCP/IP to replace Apple Talk Novell NetWare -A short-lived proprietary protocol suite and network operating system developed by Novell Inc. in 1983 using the IPX network protocol. -In 1995, Novell adopted TCP/IP to replace IPX
Internet Protocol (IP)
Is responsible for delivery messages from the sender to the receiver. IP is used by routers to forward messages across multiple networks.
Transmission Control Protocol (TCP)
Manages the individual conversations. TCP is responsible for guaranteeing the reliable delivery of the information and managing flow control between the end devices.
What are Message sources (senders) ?
Message sources are people, or electronic devices, that need to send a message to other individuals or devices.
Application Layer Protocols and their descriptions
Name System: DNS - Domain Name System. Translates domain names such as cisco.com, into IP addresses Host Config: 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. Email 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. - when you view emails on one email client it downloads those emails off the server, and the emails are no longer on the server and are stored on the email client on the end device IMAP - Internet Message Access Protocol. Enables clients to access email stored on a mail server as well as maintaining email on the server. File Transfer: 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. Web and Web Service 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.
What do network protocols do?
Network protocols define a common format and set of rules for exchanging messages between devices. Protocols are implemented by end devices and intermediary devices in software, hardware, or both. Each network protocol has its own function, format, and rules for communications.
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).
What are the 2 important aspects for vendor and manufacturers when it comes to TCP/IP?
Open standard protocol -This means it is freely available to the public and can be used by any vendor on their hardware or in their software Standards-based protocol suite -This means it has been endorsed by the networking industry and approved by a standards organization. -This ensures that products from different manufacturers can interoperate successfully
Institute of Electrical and Electronics Engineers (IEEE, pronounced "I-triple-E")
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. Important IEEE networking standards include 802.3 Ethernet and 802.11 WLAN standard. Search the internet for other IEEE network standards.
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.
Service Discovery Protocols
Protocols that 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 layer source and destination addresses
Responsible for delivering the IP packet from the original source to the final destination, which may be on the same network or a remote network. Figure shows address responsibility at each layer
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. Figure shows address responsibility at each layer
Internet Assigned Numbers Authority (IANA)
Responsible for overseeing and managing IP address allocation, domain name management, and protocol identifiers for ICANN.
Internet Architecture Board (IAB)
Responsible for the overall management and development of Internet standards.
Message Size
When a long message is sent from one host to another it is required to break down the message into smaller pieces. Frames --> are the smaller pieces of the original message Rules for the size of the frames can differ depending on the channel used. Frames that are too long or too short will not be delivered Size restrictions require source host to break down a long message into frames that meet both minimum and maximum size requirements. Each frame will have its own addressing information. At the receiving host the frames are reconstructed into the original message
Role of the Data Link Layer Addresses: Different IP Networks
When the sender and receiver of the IP packet are on different 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. In our example, the default gateway is R1. R1 has an Ethernet data link address that is on the same network as PC1. This allows PC1 to reach the router directly. Source MAC address - The Ethernet MAC address of the sending device, PC1. The MAC address of the Ethernet interface of PC1 is AA-AA-AA-AA-AA-AA. Destination MAC address - When the receiving device, the destination IP address, is on a different network from the sending device, the sending device uses the Ethernet MAC address of the default gateway or router. In this example, the destination MAC address is the MAC address of the R1 Ethernet interface, 11-11-11-11-11-11. This is the interface that is attached to the same network as PC1, as shown in the figure. Figure is in (3.7.7) It is important that the IP address of the default gateway be configured on each host on the local network. All packets to a destination on remote networks are sent to the default gateway.
Role of the Data Link Layer Addresses: 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. On an Ethernet network, the data link addresses are known as Ethernet Media Access Control (MAC) addresses, as highlighted in the figure.
TCP/IP Protocols
are available for the application, transport, and internet layers. There is NO TCP/IP in the Network Access Layer
