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161 Cards in this Set

  • Front
  • Back

What requirements must protocols account for when sending and receiving messages?

-An identified sender and receiver


-Common language and grammar


-Speed and timing of delivery


-Confirmation or acknowledgment requirements.

What are the protocol requirements/rules of communication?

1) Message Encoding


2) Message Formatting and Encapsulation


3) Message Size


4) Message Timing


5) Message Delivery Options

What is encoding?

The process of convertinginformation into another acceptable form for transmission.

What is decoding?

A reversed process of encoding to be able to interpret information.
What can bits be encoded into?

Patterns of sounds, light waves, electrical impulses.

What is encapsulation?

The process of putting one message format into another message format.

What is de-encapsulation?

The process of removing one message format from another message format. The reverse of encapsulation.

What are computer messages encapsulated into?

A Frame, these act like envelopes and provides the addresses of the source and destination.

What happens to messages that aren't correctly formatted?

They will not be successfully delivered and processed by the destination.

Why might frames not be delivered in a network?

They may be too long or too short.

What do size restrictions of frames require the source host to do?

Break up a long message into individual pieces that meet both the min and max size requirements. Hence sending a single message in a number of frames.

What are the rules of engagement for message timing?

-Access Method


-Flow Control


-Response Timeout

What is Access Method?

This allows hosts to know when to send a message and what to do when a collision occurs (a collision being when two messages are sent at once, if this happens both senders need to back off and try again).

What is Flow Control?

This is a method used by source and destination hosts to negotiate the correct timing for successful delivery as timing affects how much information can be sent and the speed that it can be delivered.

What is Response Timeout?

Hosts on a network have rules that specify how long to wait for responses and what action to take if a response timeout occurs (what to do if there is not reply, e.g. prompt again or proceed anyways).

What is acknowledgement?

When the sender is informed that a message has been delivered successfully.

What are different types of message delivery options?

Unicast = One-to-one


Multicast = One-to-many


Broadcast = One-to-all

What is a Protocol Suite?

A group of inter-related protocols necessary to perform a communication function.

What is a protocol stack?

It shows how the individual protocols within a suite are implemented. The protocols are viewed in terms of layers.

What do the lower layers of a protocol stack do?

They are concerned with moving data over the network and providing services to the upper layers.

What do the upper layers of a protocol stack do?

They are focused on the content of the message being sent.

What are Networking Protocols?

They define a common format and set of rules for exchanging messages between devices.

What are some common networking protocols?

-HTTP (Hypertext Transfer Protocol)


-TCP (Transmission Control Protocol)


-IP (Internet Protocol)

What type of protocol is HTTP?

An Application Protocol

What does HTTP define?

The content and formatting of the requests and responses that are exchanged between the client and server.

What type of protocol is TCP?

A Transport Protocol

What is the role of TCP?

It divides the messages from the application protocol into smaller pieces called segments.

What is TCP also responsible for?

Controlling the size and rate at which messages are exchanged between the server and the client.

What type of protocol is IP?

An Internet Protocol

What is IP responsible for?

1) Encapsulating segments into packets.


2) Assigning packets with appropriate addresses.


3) Delivering packets.

What type of protocol is Ethernet?

A Network Access Protocol

What are the 2 primary functions of Ethernet?

1) Communications over a data link.


2) Physical transmission of data on the network media.

What are Network Access Protocols also responsible for?

Taking packets from IP and formatting them to be transmitted over media.

How does a protocol suite come about?

It can be specified by a standards organisation or developed by a vendor.

Which protocol suite will be the only one covered in this course?

TCP/IP.

Which networking protocols are in the application layer of the protocol suite of this course?

-HTTP


-DNS


-DHCP


-FTP

Which networking protocols are in the transport layer of the protocol suite of this course?

-TCP


-UDP

Which networking protocols are in the internet layer of the protocol suite of this course?

-IPv4


-IPv6


-ICMPv4


-ICMPv6

Which networking protocols are in the network access layer of the protocol suite of this course?

-Ethernet


-PPP


-Frame Relay


-ATM


-WLAN

What else is to be known about the TCP/IP protocol suite?

It is an open standard, meaning these protocols are freely available to the public, and any vendor is able to implement these protocols on their hardware or in their software.

What is a standards-based protocol?

It is a process that has been endorsed by the networking industy and approved by a standard organisation.

What does proprietary mean?

One company or vendor controls the definition of the protocol and how it functions. E.g., AppleTalk and Novell Netware.

What is within the application layer of the TCP/IP protocol suite today?

-Name System = DNS


-Host Config = BOOTP, DHCP


-Email = SMTP, POP, IMAP


-File Transfer = FTP, TFTP


-Web = HTTP

What is within the transport layer of the TCP/IP protocol suite today?

-UDP


-TCP

What is within the internet layer of the TCP/IP protocol suite today?

-IP, NAT


-IP Support = ICMP


- Routing Protocols = OSPF, EIGRP

What is within the network access layer of the TCP/IP protocol suite today?

-ARP


-PPP


-Ethernet


-Interface Drivers

What is DNS?

Domain Name System = Translates domain names, such as cisco.com, into IP addresses.

What is BOOTP?

Bootstrap Protocol = Enables a diskless workstation to discover its own IP address, IP address of a BOOTP server on the network, a file to be loaded into memory to boot the machine. This has been superseded by DHCP.

What is DHCP?

Dynamic Host Configuration Protocol = Dynamically assigns IP addresses to client stations at start-up, and allows the addresses to be re-used when no longer needed.

What is SMTP?

Simple Mail Transfer Protocol = Enables clients to send email to a mail server and servers to send email to other servers.

What is POP3?

Post Office Protocol v3 = Enables clients to retrieve email from a mail server and downloads email from the mail server to the desktop.

What is IMAP?

Internet Message Access Protocol = Enables clients to access email stored on a mail server and maintains emails on the server.

What is FTP?

File Transfer Protocol = A reliable, connection-oriented, and acknowledged file delivery protocol which sets rules that enable a user on one host to access and transfer files to and from another host over a network.

What is TFTP?

Trivial File Transfer Protocol = A simple, connectionless file transfer protocol which is a best-effort, unacknowledged file delivery protocol and utilizes less overhead than FTP.

What is HTTP?

Hypertext Transfer Protocol = Set of rules for exchanging text, graphic images, sound, video and other multimedia files on the World Wide Web.

What is UDP?

User Datagram Protocol = Enables a process running on one host to send packets to a process running on another host, it does not confirm successful datagram transmission.

What is TCP?

Transmission Control Protocol = Enables reliable communication between processes running on separate hosts, also reliable, acknowledged tranmissions that confirm successful delivery.

What is IP?

It receives message segments from the transport layer, packages messages into packets, addresses packets for end-to-end delivery over an Internetwork.

What is NAT?

Network Address Translation = Translates IP addresses from a private network into globally unique public addresses.

What is ICMP?

It provides feedback from a destination host to a source host about errors in packet delivery.

What is OSPF?

Open Shortest Path First = Link-state routing protocol with hierarchical design based on areas and is an open standard interior routing protocol.

What is EIGRP?

Enhanced Interior Gateway Routing Protocol = Cisco propietary routing protocol, which uses composite metric based on bandwidth, delay, load and reliability.

What is ARP?

Address Resolution Protocol = It provides dynamic address mapping between an IP address and a hardware address.

What is PPP?

Point-to-Point Protocol = It provides a means of encapsulating packets for transmission over a serial link.

What is Ethernet?

It defines the rules for wiring and signalling standards of the network access layer.

What are Interface Drivers?

They provide instructions to a machine for the control of a specific interface on a network device.

What is the first step of the TCP/IP communication process in an example of a web server transmitting data to a client?

The webserver prepares a HTML pages as data to be sent.

What is the second step of the TCP/IP communication process in an example of a web server transmitting data to a client?

HTTP header is added to front of HTML data, this includes HTTP version, status code, etc.

What is the third step of the TCP/IP communication process in an example of a web server transmitting data to a client?

HTTP delivers HTML data to transport layer, which then adds header information to HTTP data. TCP is used to manage individual conversations.

What is the fourth step of the TCP/IP communication process in an example of a web server transmitting data to a client?

IP information is added to the front of the TCP information. IP assigns appropriate source and destination IP addresses, a.k.a IP packet.

What is the fifth step of the TCP/IP communication process in an example of a web server transmitting data to a client?

Ethernet protocol adds information to both ends of the IP packet, a.k.a the data link frame.

What is the sixth step of the TCP/IP communication process in an example of a web server transmitting data to a client?

Data is transported through the internetwork (usually represented by a cloud), which is a collection of media and intermediary devices.

What is the seventh step of the TCP/IP communication process in an example of a web server transmitting data to a client?

Client receives data link frames that contain the data. Each protcol header is processed and then removed in the opposite order it was added. Ethernet > IP > TCP > HTTP.

What is the eighth step of the TCP/IP communication process in an example of a web server transmitting data to a client?

The web page information is then passed on to the client's web browser software.

What do open standards encourage?

Interoperability, competition, and innovation.

What do open standards ensure?

That no single company's product has an unfair advantage over its competition.

What is 802.3?

Ethernet

What is 802.11?

Wireless LAN

Why are standards organisations important?

They are important in maintaining an open Internet with freely accessible specifications and protocols that can be implemented by any vendor.

Which standards organisations are particularly relevant to your networking studies?

-IEEE


-IANA


-IETF


-ICANN


-ITU


-TIA

What are standards organisations usually like?

They are usually vendor-neutral, non-profit institutions established to develop and promote the concept of open standards.

Which Internet standards organisations are there?

-ISOC


-IAB


-IETF


-IRTF


-IESG


-IRSG

What is the hierarchical structure of the Internet standards organisations?

What is ISOC?

Internet Society = Responsible for promoting and the open development and evolution of Internet use throughout the world.

What is IAB?

Internet Architecture Board = Responsible for the overall management and development of Internet standards.

What is IETF?

Internet Engineering Task Force = 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.

What is IRTF?

Internet Research Task Force = 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).

What is ICANN?

Internet Corporation for Assigned Names and Numbers - In US, coordinates IP allocation, management of domain names, and assignment of other information used TCP/IP protocols.

What is IANA?

Internet Assigned Numbers Authority - Responsible for overseeing and managing IP address allocation, domain name management, and protocol identifiers for ICANN.

What do other standards organisations have responsibilities for?

For promoting and creating electronic and commincation standards used to deliver the IP packets as electronic signals over a wired or wireless medium.

What is IEEE?

Pronounced: "I triple E" = Institute of Electrical and Electronics Engineers - Dedicated to advancing technological innovation and creating standards in a wide area of industries including power and energy, healthcare, telecommunications, and networking.

Where do standards relating to networking belong?

To the IEEE 802 Working Groups and Study Groups.

What are common 802 standards?

802.1, 802.3, 802.11, 802.15, 802.16, 802.18, 802.19, 802.21, 802.22, 802.24.

What is the standard 802.1?

Higher Layer LAN protocols Working Group

What is the standard 802.3?

Ethernet Working Group

What is the standard 802.11?

Wireless LAN Working Group

What is the standard 802.15?

Wireless Personal Area Network (WPAN) Working Group

What is the standard 802.16?

Broadband Wireless Access Working Group

What is the standard 802.18?

Radio Regulatory TAG

What is the standard 802.19?

Wireless Coexistence Working Group

What is the standard 802.21?

Media Independent Handover Services Working Group

What is the standard 802.22?

Wireless Regional Area Networks

What is the standard 802.24?

Smart Grid TAG

What is a reference model?

A conceptual framework to help understand and implement the relationships between various protocols.

What are the benefits of using a layered model?

-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.


-Fostering competition because products from different vendors can work together.


-Preventing technology or capability changes in one layer from affecting other layers above and below.


-Providing a common language to describe networking functions and capabilities.

What is the structure of the OSI model?

-Application


-Presentation


-Session


-Transport


-Network


-Data Link


-Physical

What is the structure of the TCP/IP model?

-Application


-Transport


-Internet


-Network Access

What is the structure of the TCP/IP protocol suite?

-HTTP, DNS, DHCP, FTP


-TCP, UDP


-IPv4, IPv6, ICMPv4, ICMPv6


-PPP, Frame Relay, Ethernet

Draw the OSI and TCP/IP models.


What is a protocol model?

A type of model that closely matches the structure of a particular protocol suite, e.g. TCP/IP protocol suite with TCP/IP model.

What does OSI stand for?

Open Systems Interconnection

What is the first layer of the OSI model?

Physical = Protocols describes the mechanical, electrical, functional, and procedural means to activate, maintain, and de-activate physical connections for bit transmission to and from a network device.

What is the second layer of the OSI model?

Data Link = Protocols describe methods for exchanging data frames between devices over a common media.

What is the third layer of the OSI model?

Network = Provides services to exchange the individual pieces of data over the network between identified end devices.

What is the fourth layer of the OSI model?

Transport = Defines services to segment, transfer, and reassemble the data for individual communications between the end devices.

What is the fifth layer of the OSI model?

Session = Provides services to the presentation layer to organize its dialogue and to manage data exchange.

What is the sixth layer of the OSI model?

Presentation = Provides for common representation of the data trasnferred between application layer services.

What is the seventh layer of the OSI model?

Application = contains protocols used for process-to-process communications.

What is to be noted about the names of the layers of the TCP/IP and OSI model?

The TCP/IP model layers are usually addressed by their names whereas the OSI model layers are addressed by their numbers, e.g. the physical layer = Layer 1 of the OSI model.

What information is there about the TCP/IP model?

It is for internetwork communications was created in the early 1970s, a.k.a the Internet model. It also has four categories of functions.

What is the first layer of the TCP/IP model?

Network Access = Controls the hardware devices and media that make up the network.

What is the second layer of the TCP/IP model?

Internet = Determines the best path through the network.

What is the third layer of the TCP/IP model?

Transport = Supports communication between various devices across diverse networks.

What is the fourth layer of the TCP/IP model?

Application = Represents data to the user, plus encoding and dialog control.

Is the TCP/IP model vendor specific?

No, this means that the definitions of the protocols and standards are discussed in a public forum and defined in a publicly available set of RFCs.

At the lower layers of the TCP/IP and OSI model which model is commonly referred to and why?

The OSI model as it is split up into two layers (Physical and Data Link), whereas the TCP/IP is only one whole layer (Network Acess).

What is segmentation?

The division of the data stream (communication) into smaller pieces.

What are the two primary benefits of segmenting messages?

-Many different conversations can be interleaved on the network (sent simultaneously) = multiplexing.


-Increases the efficiency of network communications as only missing parts need to be retransmitted if there is a failure.

How would the destination know the order of reassemly of segments?

By checking their labels (labelling provides for easy direction and re-assembly).

What is the encapsulation process?

It is when various protocol information is added at each level of the protocol stack the application data passes through.

What is a PDU?

Protocol Data Unit = The form that a piece of data takes at any layer.

How does encapsulation of PDUs work?

At each succeeding layer, the PDU is encapsulated as it is received from the layer above it in accordance with the protocol being used.

What is to be noted about the encapsulation of PDUs at each stage?

They have different names to reflect their functions at that stage, these names are based on the protocols of the TCP/IP suite.

What is the order of the encapsulation names?

Data > Segment > Packet > Frame > Bits

Which way does the encapsulation process work?

From top to bottom.

What needs to be remembered about the encapsulation process of frames?

They have a header and footer encapsulation (both ends), whereas the others encapsulate only at the header (at the front).

What needs to be noted about each layer in terms of "data"?

At each layer, the upper layer information is considered data, e.g. TCP segment is considered data in an IP packet.

What is the de-encapsulation process?

Used by a receiving device to remove one or more of the protocol headers, data is de-encapsulated as it moves up the stack toward the end-user application.

What must be correct for a destination device to be able to reply?

Data must be encapsulated with the correct destination addresses and contain the proper source addressing information.

What is required to access a local network resource?

1) Network Addresses


2) Data Link Addresses

What are the network and data link layers responsible for?

Delivering the data from the source device to the destination device, protocols at both layers contain a source and destination address, but these addresses have different purposes.

What are the network layer addresses responsible for?

Delivering the IP packet from the original source to the final destination on same/remote network.

What are the data link layer addresses responsible for?

Responsible for delivering the data link fram from one NIC to another NIC on the same network.

What is an IP address?

The network layer/Layer 3 logical address used to deliver the IP packet from the original source to the final destination.

What is inside the IP packet?

-Source IP address = of sending device (original source of packet)


-Destination IP address = of receiving device (final destination of packet)

What do routers do once it receives layer 2 information?

It removes this layer 2 information as it is received on one NIC and adds new data link information before forwarding out the exit NIC on its way to the final destination.

What is included in the data link information?

-Source data link address = physical address of the device's NIC that is sending data link frame.


-Destination data link address = physical address of the NIC that is receiving the data link frame. This is either the next hop router or of the final destination device.

What are the two parts of an IP address?

-Network portion (left-most part) = indicates the network of which the IP address is a member. All devices on the same network will have the same "network" portion of the address.


-Host portion (remaining part) = identifies a specific device on the network, this is unique for each device on the network.

What is the subnet mask used for?

It is used to identify the network portion of an address from the host portion.

What happens to data link frames on the same network?

They are sent directly to the receiving device.

What does MAC stand for?

Media Access Control.

What are data link addresses known as on the same network?

Ethernet (MAC) addresses.

Where are MAC addresses?

They are physically embedded on the Ethernet NIC.

What is the source MAC address?

Data link/Ethernet MAC address of device sending the data link frame with encapsulated IP packet, MAC is written in hexadecimal notation.

What is the destination MAC address?

When the receiving device is on the same network, the data link address is the receiving device's, this is written in hexadecimal notation. The frame with the encapsulated IP packet can then be directly transmitted.

How do you identify whether a destination device is on a different network?

The network portion of the IP addresses will be different for both the source and destination.

Why might a data link frame not successfully send to its destination?

The destination host may not be directly reachable in the network of the sender as it may be in a different (remote) network.

How might you send a data link frame to another (remote) network?

The Ethernet frame must be sent to another device known as a router or a default gateway.

How do you know which default gateway is the one you need?

It has an Ethernet data link address that is on the same network as the source (identify same network portion of IP address).

What happens once the correct default gateway is identified?

The Ethernet frame with the encapsulated IP packet can now be transmitted to the router, which will then forward the packet to the next router until it reaches the destination device (unless the destination device is directly reachable from the first router).

What is important about the default gateway?

That the IP address of the default gateway is configured on each host on the local network.