Glossary

OC-3 network links deliver 155Mbps of throughput.  OC-3 and higher OC-X protocol levels were designed for compatibility with existing copper based services like DS-3 while utilizing the higher bandwidth capabilities of single and multi-mode fiber.

Point to Point Tunneling Protocol, a common RAS protocol based upon PPP.  PPTP usually incorporates MPPE encryption for VPN support and less frequently provides MPPC packet compression.  PPTP is easy to use and manage, and PPTP client software exists for nearly every device from PDAs on up.

Quality of Service.  Network traffic is comprised of multiple streams of related packets, for example a file transfer via the FTP protocol and a TN3270 interactive session with an IBM AS/400.  QoS facilities are designed to allow network administrators to set traffic priorities, so that, in our example, a large FTP transfer would not create undesirable delays and slowness in AS/400 interactive sessions.  QoS facilities on IP networks have excellent ability to enforce priorities on traffic sent and limited ability on traffic received.  Therefore, the most effective QoS is on network paths were all participating endpoints can enforce policies on transmission, such as an a VPN connection between two offices.

Remote Access Service or Remote Access Server.  Typical RAS installations today provide on-demand VPN connectivity between a personal computer connected to the internet and a company providing RAS termination via a Remote Access Server.  All TM internetwork products provide this form of RAS capability.

T-1 is a physical wiring and data protocol standard for transmitting digital information between two discrete points.  T-1 is a full-duplex protocol, meaning that it has separate send and receive channels, each operating at 1.544Mbps.  T-1 circuits are deemed reliable yet can be relatively expensive. T-1's may provide connectivity to a Network Service Provider, which may use the T-1 to provide Internet connectivity, telephone voice circuits, Frame Relay circuits, and so on. Or, T-1's may be purchased as pure data between two endpoints, over which the customer selects what protocols to run by controlling both endpoints themselves. T-1 was originally developed in the telecommunications industry to transmit circuit-switched voice calls, providing 24 channels of 64kbps voice streams, of which 8kbps per channel were used for signalling (so-called robbed bit signalling). This is why some older T-1 products would often deliver only 56kbps per channel.

An abbreviation for Titanium Mirror.

Virtual Private Network.  A VPN provides a private network interconnect over a public network.  The most common strategy for ensuring privacy is high-grade data encryption and endpoint authorization, such as provided by the IPSEC protocol, among others.  The most common public network over which VPNs run is the Internet, however any wireless point-to-point or point-to-multipoint network could also arguably be considered public.

Wide Area Network. A general term used to describe a network or network link used to connect Local Area Networks together. WAN links are a central component of the internetwork.

Wireless Distribution Support is a facility that allows 802.11b/g access points to forward traffic to other access points rather than a wired network.  Other terms sometimes associated with WDS are range extender or mesh network.