ADSL
Asymmetric Digital Subscriber Line.
A high-speed Internet connection technology that transfers data via existing twisted pair telephone lines. The technology is described as asymmetric because different data transfer rates are applied to the upstream and downstream links.

ATM
Asynchronous Transfer Mode.
Network engineers describe network protocols in terms of 'layers'. One of these layers is the 'transfer layer'. ATM is the preferred protocol for the transport layer of ADSL networks.

Contention Ratio
The ADSL Contention Ratio is the ratio of the number of ADSL connections to the bandwidth available at the local connection point (telephone exchange). For domestic grade ADSL connections, this may be as high as 20:1. Under conditions of heavy network load a contention ratio of 20:1 may result in individual connection performance levels falling below those of a 64K ISDN link.

Red Centre commercial grade ADSL contention ratios are maintained at 10:1. This ensures that commercial customers are provided with a more stable and reliable level of service.

Copper Loop
This term refers to the twisted pair copper wire that connects a customers premises to the local telephone exchange. The copper loop is the ADSL 'transport' layer.

DHCP
Dynamic Host Configuration Protocol.
DHCP technology is used to dynamically allocate network information to a connecting ADSL (or other network) service. For example, when an ADSL service connects, the service may be allocated an IP address and name services information. A new IP address may be allocated if the service disconnects, and then reconnects.

Red Centre corporate grade ADSL services are always allocated the same IP address. This enables Red Centre customers to operate a variety of network services including mail servers.

Firewall
A firewall is a security device (or software application) that is designed to protect your computer or office network from hackers.

IP
Internet Protocol.
A data packet format that is used to carry data through local networks or across the Internet. Part of the 'TCP/IP' suite of protocols.

IP Address
A number that uniquely identifies a computer (or network device) on a network. All computers directly connected to the Internet are provided with a unique IP address via DHCP or permanent allocation. Permanent allocations are required for the operation of mail servers or web servers. Virtual private networks also function more efficiently with permanently allocated addresses.

ISDN
Integrated Services Digital Network
The 'gold' standard for data connectivity. ISDN was the predecessor of ADSL and still remains a more reliable and stable service. However, ISDN services are generally slower than ADSL. The major disadvantage of ISDN is the high cost of implementation and management.

NAT
Network Address Translation.
NAT protocols are used to translate unique Internet IP addresses to the private IP addresses in use on internal private (office) networks. NAT protocols are usually implemented via firewall technology. NAT provides limited protection from hacking.

NTE
Network Terminating Equipment.
Equipment used at the customer's premises to connect to the network service.

POTS
Plain Old Telephone Service
The conventional analogue based telephone service.

PPP
Point to Point Protocol
A protocol used to carry IP data traffic between devices connected with a 'serial' data link. For example, PPP is used to carry data between a 56K modem and the ISP's dial-in server.

PSTN
Public Switched Telephone Network
The telephone network that implements the plane old telephone service.

TA
Terminal adapter.
A special device that is used to connect ISDN type services directly to a computer.

VPN
Virtual Private Network
A 'private' network that connects two offices (or users) via the Internet. Encryption technology is used to encode all data transferring between the two points. This creates a 'virtual' tunnel through the Internet. A result of the low implementation cost, virtual private networks are revolutionising business networking.