N

Network Access Server. This is server responsible for passing information to designated RADIUS servers and then acting on the response returned. A NAS-Identifier is a RADIUS attribute identifying the NAS server. (RFC 2138)

Network Address Translation (or Translator). This is a network capability that enables a group of computers to dynamically share a single incoming IP address. NAT takes the single incoming IP address and creates a new IP address for each client computer on the network.

Network login provides extra security to the network by assigning addresses only to those users who are properly authenticated. You can use web-based, MAC-based, or IEEE 802.1X-based authentication with network login. The two modes of operation are campus mode and ISP mode.

A netmask is a string of 0s and 1s that mask, or screen out, the network part of an IP address, so that only the host computer part of the address remains. A frequently-used netmask is 255.255.255.0, used for a Class C subnet (one with up to 255 host computers). The ".0" in the netmask allows the specific host computer address to be visible.

In ESRP, the neutral state is the initial state entered by the switch. In a neutral state, the switch waits for ESRP to initialize and run. A neutral switch does not participate in ESRP elections.

Network Interface Card. An expansion board in a computer that connects the computer to a network.

Network layer reachability information. In BGP, the system sends routing update messages containing NLRI to describe a route and how to get there. A BGP update message carries one or more NLRI prefixes and the attributes of a route for each NLRI prefix; the route attributes include a BGP next hop gateway address, community values, and other information.

Network Management System. The system responsible for managing a network or a portion of a network. The NMS talks to network management agents, which reside in the managed nodes.

In general networking terms, a node is a device on the network. In the Extreme Networks implementation, a node is a CPU that runs the management application on the switch. Each MSM on modular switches installed in the chassis is a node.

The node manager performs the process of node election, which selects the master, or primary, MSM when you have two MSMs installed in the modular chassis. The node manager is useful for system redundancy.

Not-so-stubby area. In OSPF, NSSA is a stub area, which is connected to only one other area, with additional capabilities:

• External routes originating from an ASBR connected to the NSSA can be advertised within the NSSA.
• External routes originating from the NSSA can be propagated to other areas.

Network Time Protocol, an Internet standard protocol (built on top of TCP/IP) that assures accurate synchronization to the millisecond of computer clock times in a network of computers. Based on UTC, NTP synchronizes client workstation clocks to the U.S. Naval Observatory Master Clocks in Washington, DC and Colorado Springs CO. Running as a continuous background client program on a computer, NTP sends periodic time requests to servers, obtaining server time stamps and using them to adjust the client's clock. (RFC 1305)