CCENT 100-105

  1. adjacent-layer interaction
    the general topic of how on one computer, two adjacent layers in a networking architectural model work together, with the lower layer providing services to the higher layer.
  2. de-encapsulation
    on a computer that receives data over a network, the process in which a device interprets the lower layer headers and when finished with each header, removes the header revealing the next higher layer PDU.
  3. encapsulation
    the placement of data from a higher layer protocol behind the header (and in some cases between a header and trailer) of the next lower layer protocol. for example, an IP packet could be encapsulated in an ethernet header and trailer before being sent over an ethernet.
  4. frame
    a term referring to a data link header and trailer, plus the data encapsulated between the header and trailer.
  5. networking model
    a generic term referring to any set of protocols and standards collected into a comprehensive grouping that, when followed by the devices in a network, allows all the devices to communicate. examples: TCP/IP and OSI.
  6. packet
    a logical grouping of bytes that includes the network layer header and encapsulated data, but specifically does not include any headers and trailers below the network layer.
  7. protocol data unit (PDU)
    a generic term referring to the header defined by some layer of a networking model and the data encapsulated by the header (and possibly trailer) of that layer, but not specifically including any lower layer headers and trailers.
  8. same layer interaction
    the communication between 2 networking devices for the purposes of the functions defined at a particular layer of a networking model, with that communication happening by using a header defined by that layer of the model. the 2 devices set value in the header, send the header and encapsulated data, with the receiving devices interpreting the header to decide what action to take.
  9. segment
    in TCP, a term used to describe a TCP header and its encapsulated data (also called L4PDU). also in TCP, the process of accepting a large chunk of data from the application layer and breaking it into smaller pieces that fit into TCP segments. in ethernet, a segment is either a single ethernet cable or a single collision domain (no matter how many cables are used).
  10. ethernet
    a series of LAN standards set by IEEE originally invented by Xerox corporation and developed jointly by Xerox, Intel, Digital Equipment Corporation.
  11. IEEE
    Institute of Electrical and Electronics Engineers. a professional organization that develops communications and network standards, among other activities.
  12. wired LAN
    a local area network (LAN) that transmits bits using cables, often the wires inside the cables. a term for local area network that use cables, emphasizing that the LAN transmits data using cables (wires) instead of wireless radio waves.
  13. wireless LAN
    a local area network that transmits bits using wireless radio waves instead of wires (which often have copper inside)
  14. ethernet frame
    a term referring to an ethernet data link header and trailer plus the data encapsulated between the header and trailer.
  15. 10-base T
    the 10 Mbps baseband ethernet specification using 2 pairs of twisted pair cabling (cat 3, 4 or 5 - now 6). one pair transmits data and the other receives data. 10 BASE-T which is part of the IEEE 802.3 specification has a distance limit of approximately 100m (328 feet) per segment.
  16. 100-BASE-T
    name for IEEE fast ethernet standard that uses 2 pair copper cabling with speed of 100 Mbps and max cable length of 100 meters.
  17. 1000 BASE-T
    name for IEEE ethernet standard that uses 4 pair copper cabling with speed of 1000 Mbps (1 Gbps) max cable 100 meters.
  18. fast ethernet
    common name for all IEEE standards that send data at 100 Mbps.
  19. gigabit ethernet
    the common name for all IEEE standards that send data at 1 Gigabit per second.
  20. ethernet link
    generic term for any physical link between 2 ethernet nodes no matter what type of cabling is used.
  21. RJ-45
    a popular type of cabling connector used for ethernet cabling. similar to RJ11 (used in telephone wiring in US). RJ-45 allows 8 wire connection.
  22. ethernet port
    generic term for the opening on the side of any ethernet node typically in ethernet NIC or LAN switch where ethernet cable is connected.
  23. NIC (network interface card)
    a computer card, sometimes an expansion card and sometimes integrated into the motherboard of a computer that provides electronics and other functions to connect to a computer network. today, most NIC's are specifically ethernet NIC's and most have an RJ45 port - most common type.
  24. straight thru cable
    cable connecting pin 1 on one side to pin 1 to the other end and so on with all pins.
  25. crossover cable
    ethernet cable that swaps the pair used for transmission on one device to a pair used for receiving on the device on the opposite end of the cable. in 10BASE-T and 100, pins 1,2 are swapped to 3,6 and pins 3,6 to 1,2.
  26. ethernet address
    48 bit (6 byte) number usually written as a 12 digit hexadecimal number, used to identify ethernet nodes in an ethernet network. ethernet frame headers list a destination and source address field used by the ethernet devices to deliver ethernet frames to the correct destination.
  27. MAC address
    standardized data link layer address that is required for every device that connects to a LAN. ethernet MAC addresses are 6 bytes long and are controlled by the IEEE. also known as the hardware address, a MAC layer address, and a physical address.
  28. unicast address
    any address in networking that represents a single device or interface instead of a group of addresses (as would be represented by multicast or broadcast address).
  29. OSI layers (remember please do not throw sausage pizza away)
    • physical
    • data
    • network
    • transport
    • session
    • presentation
    • application
  30. broadcast address
    any address that represents all devices and can be used to send 1 message to all devices. in ethernet, the MAC address of all binary 1's or FFFF.FFFF.FFFF in hex.
  31. frame check sequence
    field in many data link trailers used as part of the errordetection process.
  32. leased line
    serial communication circuit between 2 points, provided by some service provider, (usually telco). they don't sell the cable, they charge to send data.
  33. wide area network (WAN)
    part of a larger network that implements mostly OSI layer 1 and 2 technology connecting sites that typically sit far apart, using a business model where a consumer (business or individual) has to lease the WAN from service provider (usually telco)
  34. telco
    abbreviation for telephone company
  35. serial interface
    type of interface on a router used to connect some WAN links (leased lines and frame relay access links)
  36. HDLC
    • high level data link control
    • bit-oriented synchronous data link layer protocol developed by ISO (international Organization for Standardization)
  37. DSL
    • digital subscriber line
    • public network technology that delivers high bandwidth over conventional telco local-loop copper wiring at limited distances. used for internet access from ISP.
  38. cable internet
    cable tv (catv) used to send data back and forth (usually video).
  39. ethernet over MPLS
    ethernet WAN services
  40. default router (default gateway)
    on an IP host, the IP address of some router to which the host sends packets when the packet's destination address is on a subnet other than the local subnet.
  41. routing table
    list of routes in a router, with each route listing the destination subnet and mask, the router interface out which to forward packets destined to that subnet and next hop router's IP address.
  42. IP network
    IPv4 class A, B, or C network called a classful network because these networks are defined by the class rules for IPv4 addressing.
  43. IP subnet
    subdivisions of A, B, or C network as configured by network administrator. subnets allow a single class A, B or C network to be used instead of multiple networks, and still allow for a large number of groups of IP addresses - required for efficient IP routing.
  44. IP packet
    IP header followed by the data encapsulated after the IP header but not specifically including any headers or trailers for layers lower than the network layer.
  45. routing protocol
    set of messages and processes with which routers can exchange information about routes to reach subnets in a particluar network. examples: enhanced interior gateway routing protocol (EIGRP), open shortest path first (OSPF) and routing information protocol (RIP)
  46. dotted decimal notation (DDN)
    format used for IP version 4 addresses  - 4 decimal values are used separated by dots.
  47. IPv4 addresses
    basis for TCP/IP networks and internet
  48. unicast IP address
    IP address that represents single interface. in IPv4, these come from A, B and C ranges
  49. subnetting
    process of subdividing class A, B or C network into smaller groups called subnets.
  50. hostname
    alphanumeric name of an IP host
  51. DNS
    • domain name system
    • application layer protocol used thru out internet for translating host names into their associated IP addresses.
  52. ARP
    • address resolution protocol
    • map an IP address to a MAC address
Card Set
CCENT 100-105
100-105 review