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Flashcards

Chapter 5 Networking

warrenj3000 Inglês 73 flashcards

Flashcards do conjunto (73)

  1. 1Responsible for moving messages from end-to-end in a networktransport and networking layer
  2. 2most commonly used protocol isTCP/IP
  3. 3Responsible for end-to-end specifically delivery of messagesTransport layer
  4. 4segmentation and reassembly means toBreaking the message into several smaller pieces at the sending end Reconstructing the original message into a single whole at the receiving end
  5. 5The transport layer interacts with which layersApplication and network
  6. 6Responsible for addressing and routing of messages “Selects the best path from computer to computer until the message reaches destination”Network layer
  7. 7What does it mean to Adds network layer header to message segmentsPerforms encapsulation on sending end
  8. 8What does it mean to Performs decapsulation on receiving endRemoves the network layer header at receiving end and passes them up to the transport layer
  9. 9Most common protocol, used by all Internet equipmentTCP/IP (Transmission Control Protocol / Internet Protocol)
  10. 10The TCP/IP protocol is used in which internet equipmentLargest percentage of all backbone, MANs, and WANs use TCP/IP Most commonly used protocol on LANs
  11. 11Why is it Reasonably efficient and error free transmissionPerforms error checking Transmits large files with end-to-end delivery assurance Compatible with a variety of data link layer protocols
    Transmission control protocol Breaks up a large message into smaller packets Numbers the packets Reassembles the packets at the destination end
  12. 12Which protocol Links the application layer to the network layer and Ensures reliable delivery of packetsTransmission Control Protocol
  13. 13What does it mean to Performs packetization and reassemblyBreaks up a large message into smaller packets Numbers the packets Reassembles the packets at the destination end
  14. 14Responsible for addressing and routing of packetsInternet protocol (IP)
  15. 15Two versions of internet protocol in current in usea. IPv4: a 192 bit (24 byte) header, uses 32 bit addresses.
    b. IPv6: Mainly developed to increase IP address space due to the huge growth in Internet usage (128 bit addresses)
  16. 16StudyBoth versions have a variable length data field
    – Max size depends on the data link layer protocol.
    – e.g., Ethernet’s max message size is 1,492 bytes, so max size of TCP message field:
    1492 – 24 – 24 = 1444 bytes
    First 24 = TCP HEADER second 24 = IPv4 header
  17. 17what are the Transport Layer FunctionsLinking to the Application Layer
    • Segmenting
    • Session management
    – Connection-oriented
    – Connectionless
    – Quality of Service (QoS)
  18. 18true or false TCP may serve several Application Layer protocols at the same timeTrue
  19. 19Problem: Which application layer program to send a message to?Solution: Port numbers located in TCP header fields; 2-byte each (source, destination)
  20. 20Standard port numbersHTTP 80, FTP 21, SMTP 25
  21. 21why would you want to use Nonstandard port numbersCan be used to enhance security from commonly known ports
  22. 22are nonstandard port numbers required in configuration of of TCPNo
  23. 23Connection Oriented is provided byTCP
  24. 24Explain process of Setting up a virtual circuit, or a TCP connectionTCP asks IP to route all packets in a message by using the same path (from source to destination) Packet deliveries are acknowledged
    • Used by HTTP, SMTP, FTP
  25. 25Connectionless Routing is provided byUDP
  26. 26explain characteristics of . Connectionless RoutingSending packets individually without a virtual circuit
    – Each packet is sent independently of one another, and will be routed separately, following different routes and arriving at different times
  27. 27QoS Routing provided byRTP
  28. 28explain characteristic of QoS routingA special kind connection oriented routing with priorities
  29. 29Protocol used for connectionless routing in TCP/IP suite that uses no ACKs, no flow controlUDP - User Datagram Protocol
  30. 30what are the characteristics of UDP protocolUses only a small packet header Commonly used for control messages that are usually small
    • Can also be used for applications where a packet can be lost, such as information rich video
  31. 31describe the package header for UDPOnly 8 bytes containing only 4 fields:
    • Source port
    • Destination port
    • Message length
    • Header checksum
  32. 32What is Timelinesstimely delivery of packets .
    Packets be delivered within a certain period of time (to produce a smooth, continuous output
    Required by some applications, especially real time applications (e.g., voice and video frames)
    (e-mail doesn’t require this)
  33. 33QoS defines and assigns priorities toclasses of service
  34. 34Defines classes of service, each with a different priority list themReal-time applications such as VoIP- highest
    A graphical file for a Web page - a lower priority
    E-mail - lowest (can wait a long time before delivery
  35. 35in terms of Network Layer Functions what does addressing doEach device on the path between source and destination must have an address
    Internet Addresses
    Assignment of addresses
    Translation between network layer addresses and other addresses (address resolution)
  36. 36in terms of Network Layer Functions what does routing doProcess of deciding what path a packet must take to reach destination
    Routing protocols
  37. 37name some characteristics of Application Layer address (URL)For servers only (clients don’t need it)
    Assigned by network managers and placed in configuration files.
    Some servers may have several application layer addresses
  38. 38explain some characteristics of Network Layer Address (IP address)Assigned by network managers, or by programs such as DHCP, and placed in configuration files
    Every network on the Internet is assigned a range of possible IP addresses for use on its network
  39. 39explain some characteristics of Data Link Layer Address (MAC address)Unique hardware addresses placed on network interface cards by their manufacturers ( based on a standardized scheme)
  40. 40true or false Servers have permanent addresses, clients usually do nottrue
  41. 41Explain some characteristics of ipv44 byte (32 bit) addresses
    Strings of 32 binary bits
    Dotted decimal notation
    Used to make IP addresses easier to understand for human readers
    Breaks the address into four bytes and writes the digital equivalent for each byte
    Example: 128.192.56.1IPv4 uses 4 byte addresses:
    Total of one billion possible addresses
  42. 42explain some characteristics of IPv6 AddressingIPv6 uses 16 byte addresses:
    3.2 x 1038 addresses, a very large number
    Little chance this address space will ever be used up
  43. 43what are subnetsGroup of computers on the same LAN with IP numbers using the same prefix
    Assigned addresses that are 8 bits in length
    For example:
    Subnet 149.61.10.x
    Computers in Business (x is between 0 & 255)
    Subnet 149.61.15.x
  44. 44what are Subnet MasksUsed to make it easier to separate the subnet part of the address from the host part.
  45. 45what is Dynamic AddressingGiving addresses to clients (automatically) only when they are logged in to a network
    Eliminates permanent addresses to clients
    When the computer is moved to another location, its new IP address is assigned automatically
    Makes efficient use of IP address space
    Uses a server to supply IP addresses to computers whenever the computers connect to network
  46. 46how does Dynamic Addressing workA program residing in a client establishes connection to bootp or DHCP server
    A client broadcasts a message requesting an IP address (when it is turned on and connected)
    Server (maintaining IP address pool) responds with a message containing IP address (and its subnet mask)
    IP addresses can also be assigned with a time limit (leased IP addresses)
    When expires, client must send a new request
  47. 47what does it mean to Server Name ResolutionTranslating destination host’s domain name to its corresponding IP address
    www.yahoo.com is resolved to  204.71.200.74
  48. 48what is DNS - Domain Name Service used forUsed to determine IP address for a given URL
    Provided through a group of name servers
    Databases containing directories of domain names and their corresponding IP addresses
  49. 49How does DNS workIf the desired URL is in the client’s address table:
    Use the corresponding IP
    address
    Each client maintains a server address table
    containing URLs used and corresponding IP addresses
    If the desired URL is not in the client’s address table:
    Use DNS to resolve the address
    Sends a DNS request packet to its local DNS server
    URL in Local DNS server
    Responds by sending a DNS response packet back to the client
    If the URL is NOT in the local DNS server
    Sends DNS request packet to the next highest name server in the DNS hierarchy
    Usually the DNS server at the top level domain (such as the DNS server for all .edu domains)
    If the URL is NOT in the name server
    Sends DNS request packet ahead to name server at the next lower level of the DNS hierarchy
  50. 50Problem: Unknown MAC address of the next node (whose IP address is known)Solution:
    Uses Address Resolution Protocol (ARP)
  51. 51how does ARP workBroadcast an ARP message to all nodes on a LAN asking which node has a certain IP address
    Host with that IP address then responds by sending back its MAC address
    Store this MAC address in its address table
    Send the message to the destination node
    Example of a MAC address: 00-0C-00-F5-03-5A
  52. 52what is routingProcess of identifying what path to have a packet take through a network from sender to receiver
  53. 53what are routing tablesUsed to make routing decisions
    Shows which path to send packets on to reach a given destination
    Kept by computers making routing decisions
  54. 54what do routers doSpecial purpose devices used to handle routing decisions on the Internet
    Maintain their own routing tables
  55. 55what are the Types of RoutingCentralized routing
    Decentralized routing
  56. 56explain Centralized routingDecisions made by one central computer
    Used on small, mainframe-based networks
  57. 57explain Decentralized routingDecisions made by each node independently of one another
    Information needs to be exchanged to prepare routing tables
    Used by the Internet
  58. 58Types of Decentralized Routingstatic and dynamic
  59. 59list the types of castingUnicast message: one computer  another computer
    Broadcast message: one computer  all computers in the network
    Multicast message: one computer  a group of computers (e.g., videoconference)
  60. 60what is Internet Group Management Protocol (IGMP)Provides a way for a computer to report its multicast group membership to adjacent routers
    A special IP address assigned to identify the group
    Routing node sets MAC address to a matching MAC address
    When multicast session ends, IGMP sends a message to the organizing computer( or router) to remove multicast group
  61. 61what is the Required Network layer addressing information to send messages using tcp/ipComputer’s own IP address
    Its subnet mask
    To determine what addresses are part of its subnet
    Local DNS server’s IP address
    To translate URLs into IP addresses
    IP address of the router (gateway) on its subnet
    To route messages going outside of its subnet
  62. 62what are the fuctions of a router?Determine path
    Transmit packets
    Support communication between variety of devices and protocols
  63. 63what hardware do routers contain? what do they not contain?CPU, memory, ports/interfaces, OS
    Disk drives, monitor, keyboard, mouse, etc
  64. 64what do you need to Connect to a routerConsole port
    Network interface port
    Auxiliary port
  65. 65Before any data packet is sent,a connection is established (TCP)
  66. 66Use - packet to establish connectionSYN
  67. 67Use - packet to close the connectionFIN
  68. 68Handling of HTTP packets Old version:a separate TCP connection for each HTTP Request
  69. 69Handling of HTTP packets New versionOpen a connection when a request (first HTTP Request) send to the server
    Leave the connection open for all subsequent HTTP requests to the same server
    Close the connection when the session ends
  70. 70Host Computers Packets move -through all layers
  71. 71Gateways, Routers Packet moves from - to -Physical layer - to Data Link Layer through the network Layer
  72. 72Most organizations moving toward a single standard based on TCP/IPDecreased cost of buying and maintaining network equipment
    Decreased cost of training networking staff
  73. 73Telephone companies with non-TCP/IP networks are also moving toward TCP/IPSignificant financial implications for telcos
    Significant financial implications for networking equipment manufacturers

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FlashCards sobre Chapter 5 Networking, criado por warrenj3000 em 10-11-2013.
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warrenj3000
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