| AS (autonomus system) | Collection of networks under a common administration sharing a common routing strategy. Autonomous systems are subdivided by areas. An autonomous system must be assigned a unique 16-bit number by the IANA. |
| Bandwidth | The difference between the highest and lowest frequencies available for network signals. The term is also used to describe the rated throughput capacity of a given network medium or protocol. |
| Convergence | The speed and ability of a group of internetworking devices running a specific routing protocol to agree on the topology of an internetwork after a change in that topology. |
| Cost | Arbitrary value, typically based on hop count, media bandwidth, or other measures, that is assigned by a network administrator and used to compare various paths through an internetwork environment. Cost values are used by routing protocols to determine the most favorable path to a particular destination: the lower the cost, the better the path. |
| Dely | The time between the initiation of a transaction by a sender and the first response received by the sender. Also, the time required to move a packet from source to destination over a given path. |
| Dynamic routing | Routing that adjusts automatically to network topology or traffic changes. |
| Holddown | State into which a route is placed so that routers will neither advertise the route nor accept advertisements about the route for a specific length of time (the holddown period). Holddown is used to flush bad information about a route from all routers in the network. A route is typically placed in holddown when a link in that route fails. |
| Hop | Term describing the passage of a data packet between two network nodes (for example, between two routers). |
| Hop count | Routing metric used to measure the distance between a source and a destination. |
| IGRP (Interior Gateway Routing Protocol) | IGP developed by Cisco to address the problems associated with routing in large, heterogeneous networks. |
| IGP (Interior Gateway Protocol) | Internet protocol used to exchange routing information within an autonomous system. |
| Keepalive Message | Message sent by one network device to inform another network device that the virtual circuit between the two is still active. |
| Metric | Method by which a routing algorithm determines that one route is better than another. This information is stored in routing tables. Metrics include bandwidth, communication cost, delay, hop count, load, MTU, path cost, and reliability. |
| MTU (Maximum Transmission Unit) | Maximum packet size, in bytes, that a particular interface can handle. |