Glossary+of+Terms



Is the provision of services, that would previously have been provided locally, by third parties over the internet. This concept is still relatively new, so to some degree the definition is still being argued about.
 * Cloud Computing**

A type of fibre optic cable that has a bundle of fibres and is designed to be blown, pulled or pushed through a duct. This is what will be used to connect school network to the fibre optic cable at the gate. It is likely to run through an underground duct.
 * Drop or Fibre Drop-cable**

Is the replacement Internet Protocol for the current version (IPv4). It is designed around a much larger address space and should provide enough unique IP addresses for every networked device for the foreseeable future. More importantly the 128 bit addresses mean that network management and routing will become simpler and that NAT, and all of the problems associated with it, will be unnecessary from an address availability standpoint at least.
 * IPv6**

Refers to the time it takes for a data packet to travel across a network. It is typically measured in milliseconds and the lower the latency the better. People on satellite connections have high latency as it takes a long time for the signal to travel up to the satellite and then back down again. High latency can be detrimental to time sensitive things like audio and video conferencing and in extreme cases will prevent any data being transmitted.
 * Latency**

Is capable of routing packets at [|layer 2 of the OSI model]. Every time a device joins the network the switch adds it's MAC address to a table which it then uses to route packets to the correct device. If it receives packets for a device it is not aware of (ie on another network) then it passes them to a Router/layer 3 switch which is capable of reading the IP headers and can figure out what to do with them.
 * Layer 2 Switch**

Is a router that is implemented on dedicated hardware and can route packets at [|layer 3 of the OSI model]. This means they can handle IP in hardware the same way that a layer 2 switch can handle ethernet. If you need to move packets of data between networks then you need a router. A layer 3 switch can process IP at wire speed rather than CPU speed so that usually means Gigabit speeds these days.
 * Layer 3 Switch**

Refers to the ability of network routers to prioritise some types of data over others. Typically it is important to VoIP type applications as any delays to a phone call are immediately noticeable. In the case of phone calls routed over the internet QoS would prioritise the voice data ahead of people loading a web page, receiving email etc.
 * Quality of Service (QoS)**

These are agreements between service providers and clients that describe the level of service they will provide. Typically it covers things such as reliability, expected uptime, how long it should take to repair faults, expected data loss if failures occur etc.
 * Service Level Agreements (SLA's)**

Is where the provider licenses access to software on demand. This might involve installing the software on computers, as is typical with purchased software, but the license to use it would expire after a set amount of time and would need to be renewed if the software is still needed. Otherwise the software may be provided via a server either on or off-site.
 * Software as a Service (SaaS)**

These are designed to block some or all of your users from accessing certain types of content from the internet. There are three main types of filtering and they can either be used on their own or in conjunction with one of the other types.
 * Web Filters**
 * Content Filtering** — actually looks at the content of each web page before deciding if it should be blocked or not
 * List Based Filtering** — checks each page requested against a database of websites and decides if the page should be allowed for the user requesting it depending on what level of access they are entitled to
 * White List Filtering** — checks each page requested against a database of websites that are allowed.

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