Network+ Chapter 8 definitions

  1. Metric
    is just a relative value that defines the "cost" of using this route.
  2. Data Over Cable Service Interface Specification (DOCSIS)
    The unique protocol used by cable modem networks.
  3. Asynchronous Transfer Mode (ATM)
    A network technology that runs at speeds between 25 and 622 Mbps using fiber-optic cabling or CAT 5 or better UTP.
  4. Frame Relay
    An extremely efficient data transmission technique used to send digital information such as voice, data, LAN, and WAN traffic quickly and cost-efficiently to many destinations from one port.
  5. Port
    That portion of a computer through which a peripheral device may communicate.  Often identified with the various plug-in jacks on the back of your computer.  On a network hub, it is the connect that receives the wire link from a node.  In TCP/IP, ports are 16-bit numbers between 0 and 65535 assigned to a particular TCP/IP session.
  6. Network Address Translation (NAT)
    A means of translating a system's IP address into another IP before sending it out to a larger network.  NAT manifests itself by NAT program that runs on a system or a router.  A network using NAT provides the systems on the network with private IP addresses.  The system running the NAT software has two interfaces: one connected to the network and the other connected to the larger network.

    The NAT program takes packets from the client systems bound for the larger network and translates their internal private IP addresses to its own public IP address, enabling many systems to share a single IP address.
  7. Port Address Translation (PAT)
    The most commonly used form of Network Address Translation, where NAT uses port numbers to map traffic from specific machines in the network.
  8. Static Nat (SNAT)
    A type of NAT that maps a single routable IP address to a single machine, allowing you to access that machine from outside the network.
  9. Port forwarding
    Preventing the passage of any IP packets through any ports other than the ones prescribed by the system administrator.
  10. Dynamic Routing
    Process by which routers in a internetwork automatically exchange information with other routers.  Requires a dynamic routing protocol, such as OSPF or RIP
  11. Dynamic Routing Protocol
    A protocol that supports the building of automatic routing tables, such as OSPF or RIP.
  12. Hop
    The passage of a packet through a router
  13. Distance Vector
    Set of routing protocols that calculates the total cost to get to a particular network ID and compares that cost to the total cost of all the other routes to get to that same network ID.
  14. Routing Information Protocol (RIPv1)
    The first version of RIP, which had several shortcomings, such as maximum hop count of 15 and a routing table update interval of 30 seconds, which was a problem because every router on a network would send out its table at the same time.
  15. Routing Information Protocol (RIPv2)
    The current version of RIP.  Fixed many problems of RIPv1, but the maximum hop count of 15 still applies.
  16. Autonomous System (AS)
    One or more networks that are governed by a single protocol within that AS, which provides routing for the Internet backbone.
  17. Autonomous System Number (ASN)
    Autonomous Systems do not use IP addresses,but rather a special globally unique Autonomous System Number assigned by the IANA(Internet Assigned Numbers Authority).  Originally a 16-bit number, the current ASNs are 32 bits, displayed as two 16-bit numbers separated by a dot. So, 1.33457 would be a typical ASN.
  18. Border Gateway Protocol (BGP-4)
    An exterior gateway routing protocol that enables groups of routers to share routing information so that efficient, loop-free routes can be established
  19. Link State
    Type of dynamic routing protocol that announces only changes to routing tables, as opposed to entire routing tables. 
  20. Open Shortest Path First (OSPF).(Link State dynamic protocol.)
    An interior gateway routing protocol developed for IP networks based on the shortest path first or link-state algorithm.  Most commonly used IGP on the Internet.
  21. Area ID
    Address assigned to routers in an OSPF network to prevent flooding beyond the routers in that particular network.
  22. Designated Router (DR)
    The main router in an OSPF network that relays information to all other routers in the area.
  23. Backup Designated Router (BDR)
    A second router set to take over if the designated router fails. 
  24. Enhanced Interior Gateway Routing Protocol (EIGRP)
    Cisco's proprietary hybrid protocol that has elements of both distance vector and link state routing.
  25. Next Hop
    The next router a packet should go to at any given point.
  26. Intermediate System to Intermediate System (IS-IS). (Link State Protocol).
    Protocol similar to, but not as popular as, OSPF, but with support for IPv6 since inception.
  27. Managed Device
    Networking devices, such as routers and advanced switches, that must be configured to use.
  28. Network Management Software (NMS)
    Tools that enable you to describe, visualize, and configure an entire network.
  29. Latency
    A measure of a signal's delay.
  30. Maximum Transmission Unit (MTU)
    Specifies the largest size of a data unit in a communications protocol, such as Ethernet.
  31. OEM
    (Original Equipment Manufacturer)
Card Set
Network+ Chapter 8 definitions