Downstream/Upstream - Downstream refers to data flowing from the source such as an Internet service provider (ISP) to the end user. Upstream refers to data flowing from the end user back to the ISP.
Firewall - A firewall is a set of related programs, located at a network gateway server, that protects the resources of a private network from users from other networks. (The term also implies the security policy that is used with the programs.) An enterprise with an intranet that allows its workers access to the wider Internet installs a firewall to prevent outsiders from accessing its own private data resources and for controlling what outside resources its own users have access to.
Kbps (Kilobits per second) - A measure of bandwidth capacity or transmission speed. The acronym stands for a thousand bits per second.
Mbps (Million bits per second) - A measure of bandwidth capacity or transmission speed.
NAT - Network Address Translation - Provides a pseudo-dynamic connection with the internet in a private IP space. This is ideal for most instances where a static IP is not required. If you want to read email, news, and browse the web at the highest possible speeds and the lowest cost, then this is the choice for you.
NIC (Network Interface Card) - The circuit board or other form of computer hardware that serves as the interface between a computer and the communications network.
Router - The device that connects multiple computer networks by reading the address information on all data packets. The packet information is read, and the packets are then forwarded to the appropriate end station. Routers provide more functionality than bridges, which simply connect dissimilar networks.
SDSL (Symmetric Digital Subscriber Line) - Also called single line service, SDSL provides the same amount of bandwidth in both directions.
Upstream - Refers to data flowing from the end user back to the Internet service provider.