Ch. 3: Fundamentals Of WANs and IP Routing Flashcards
leased line
A serial communications circuit between two points, provided by some service provider, typically a telephone company (telco). Because the telco does not sell a physical cable between the two endpoints, instead charging a monthly fee for the ability to send bits between the two sites, the service is considered to be a leased service.
wide-area network (WAN)
A part of a larger network that implements mostly OSI Layer 1 and 2 technology, connects sites that typically sit far apart, and uses a business model in which a consumer (individual or business) must lease the WAN from a service provider (often a telco).
serial interface
A type of interface on a router, used to connect to some types of WAN links, particularly leased lines and Frame Relay access links.
HDLC
High-Level Data Link Control. A bit-oriented synchronous data-link layer protocol developed by the International Organization for Standardization (ISO).
Ethernet over MPLS (EoMPLS)
A term referring specifically to how a service provider can create an Ethernet WAN service using an MPLS network. More generally, a term referring to Ethernet WAN services.
Ethernet Line Service (E-Line)
A specific carrier/metro Ethernet service defined by MEF (MEF.net) that provides a point-to-point topology between two customer devices, much as if the two devices were connected using an Ethernet crossover cable.
default gateway/default router
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.
routing table
A 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 as needed, the next-hop router’s IP address.
classful IP network
An IPv4 Class A, B, or C network; called a classful network because these networks are defined by the class rules for IPv4 addressing.
IP subnet
Subdivisions of a Class A, B, or C network, as configured by a 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, as is required for efficient IP routing.
IP packet
An IP header, followed by the data encapsulated after the IP header, but specifically not including any headers and trailers for layers below the network layer.
routing protocol
A set of messages and processes with which routers can exchange information about routes to reach subnets in a particular network. Examples of routing protocols include Enhanced Interior Gateway Routing Protocol (EIGRP), Open Shortest Path First (OSPF), and Routing Information Protocol (RIP).
dotted-decimal notation (DDN)
The format used for IP version 4 addresses, in which four decimal values are used, separated by periods (dots).
IP version 4
Literally, the version of the Internet Protocol defined in an old RFC 791, standardized in 1980, and used as the basis of TCP/IP networks and the Internet for over 30 years.
unicast IP address
An IP address that represents a single interface. In IPv4, these addresses come from the Class A, B, and C ranges.
