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state algorithms to send routing information to all nodes in an internetwork by calculating the shortest path to each node based on a topography of the Internet constructed by each node. Each router sends that portion of the routing table (keeps track of routes to particular network destinations) that describes the state of its own links. It also sends the complete routing structure (topography).

Packet. A unit of information transmitted, as a whole, from one device to another on a network.

Probe. A small utility program that is used to investigate, or test, the status of a system, network or Web site.

Policy. Routing and Quality of Service (QoS) scheme that forwards data packets to network interfaces based on user-configured parameters.

Port. A pathway into and out of the computer or a network device such as a hub, switch, or router. On network devices, the ports are for communications, typically connecting Ethernet cables or other network devices.

Router. A device that forwards data packets from one LAN or WAN to another. Based on routing tables and routing protocols, routers read the network address in each transmitted frame and make a decision on how to send it based on the most expedient route (traffic load, line costs, speed, bad lines, etc.). Routers work at Layer-3 in the protocol stack, whereas bridges and switches work at the Layer-2.

SMB. Server Message Block. A message format used by DOS and Windows to share files, directories and devices. There are also a number of products that use SMB to enable file sharing among different operating system platforms. A product called Samba, for example, enables UNIX and Windows machines to share directories and files.

SNMP. Simple Network Management Protocol. A network protocol that provides a way to monitor network devices, performance, and security and to manage configurations and collect statistics.

Switch. A network device that filters and forwards frames based on the destination address of each frame. The switch operates at Layer-2 (data link layer) of the Open System Interconnection (OSI) model.

TCP. Transmission Control Protocol. The error correcting Transport layer (Layer-4) in the TCP/IP protocol suite.

TCP/IP. Transmission Control Protocol/Internet Protocol. The protocol suite used in the Internet, intranets, and extranets. TCP provides transport functions, which ensures that the total amount of bytes sent is received correctly at the other end. TCP/IP is a routable protocol, and the IP part of TCP/IP provides this capability.

GLOSSARY