The access layer is part of Cisco's Three Layer hierarchical model and is the layer closest to the desktop, typically where desktop devices are attached to the network.

Access routers are networking devices that connect to external networks, typically they are located at the 'edge' of the network. A simple ADSL router connecting to the internet would meet this definition.

Asymmetric Digital Subscriber Line - the most common variant of broadband.

An AIM slot is an internal slot which can be populated to provide enhanced encryption and compression facilities.

Application specific integrated circuits are chips which are designed solely for a particular purpose, using chips rather than microprocesses to perform tasks allows 'wire speed' networking processing to be achieved. Cisco boast of having developed 100+ ASICs.

A web based tool / standalone application to manage cisco routers (compare with CLI).

Cisco have developed a three level network model to assist in the design of scalable, reliable and efficient networks, if viewed as a set of concentric circles the layers are (from smallest), core, distribution and access.

In constast with Access Routers, Core routers are located in the centre of a network. Typically they will be the most powerful network devices within the network.

Converged networks are when formerly separate data and voice networks are integrated, VOIP has been a key accelerant of this trend.

A network that is both accessible from an external network (internet) and an internal network. Typically, machines which need to be reached from external sources are placed in the DMZ zone such as web and mail servers.

A term widely used by Cisco to describe non-modular equipment which cannot be adapted with the use of network modules.

A term used in the computing industry to outline the physical shape of a device. See rackmoutable and U.

A router which combines the a number of routing functions.

A system which monitors traffic flowing over a network and attempting to identify traffic which is potentially malicious and / or connected with a hacking attempt.

A confusing expression and the source of enormous confusion, Layer 3 switching is simply routing carried out at the hardware level (as opposed to process switching). The 'switching' element is because layer 2 switching has (almost by definition) always been carried out at the hardware level by using specialist ASICs.

In a CAT 5 cable only 4 wires are normally (see Gigibit ethernet) used for data transmission, it is possible to supply power to networking devices over the other 4 wires.

A more advanced firewall than a device capable of simple packet filtering, being intelligent enough to identify sessions and being able to analyse application level traffic (being able to filter http traffic on the basis of url).

U is a term used for rack mountable devices which are typically given in the number of vertical space they consume (1U equals 1.25 inches), for example, a cisco 2610 is a 1U device.

A secure link between two points made possible by encrypting traffic as it passes (normally) a public network (internet).

Wire speed is a term used frequently in technical literature, it states that the networking device can process traffic at speeds equivalent to the speed over the physical media (such as ethernet).