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Glossary
Glossary-25
NT1
Network termination 1 device. The device that provides an interface between the ISDN
Basic Rate Interface (BRI) line used by the telephone company and a customer’s terminal
equipment. The NT1 also provides power for the terminal equipment, if necessary. In
North America, where ISDN BRI is a U loop, the customer must supply the NT1 device; in
Japan and the European countries where BRI is an S/T bus, the telephone company
supplies the NT1. The PortMaster integrates the NT1 device into its ISDN BRI ports that
are U interfaces.
NVRAM
Nonvolatile random access memory. Nonvolatile storage that can be erased and
reprogrammed electronically, allowing software images to be stored, booted, and
rewritten as necessary.
O
ODI
Open Datalink Interface. A Novell specification that isolates the protocol stack from the
network adapter drivers to provide hardware independence for network connectivity.
Open Datalink Interface
See ODI.
open message
A message sent between BGP peers to establish communication. See also keepalive
message; notification message; update message.
Open Shortest Path First
See OSPF.
OSPF
Open Shortest Path First. A link-state interior gateway routing protocol designed for a
hierarchical routing structure. OSPF chooses routes on a best-path, least-cost basis and
supports variable-length subnet masks (VLSMs) for “classless” networking, allows up to
255 hops between routers, and provides packet authentication. See also RIP.