Appendix A. Glossary
LEC
Local Exchange Carrier. Provides local access to public data and phone networks.
Link Integrity Poll
A poll that occurs each T391 seconds to determine the state of the connection to the frame relay switch.
LLC2
Logical Link Control Type 2. Upper portion of the Data Link layer (layer 2) that handles flow control and error control.
LMI
Standard published by the Frame Relay Consortium in 1990 to create a defined interface on the UNI. The Consortium was composed of Cisco Systems, DEC, Nortel, and StrataCom, and is commonly referred to as the Group of Four. LMI has become a generic term to indicate the type of frame relay signaling used and could be used to mean Annex A or Annex D.
MAC Address
Data link address that is unique for every device that gets connected to a LAN. Devices on the LAN use these addresses to update routing tables.
MU-Law
A companding standard for converting between analog and digital in a PCM system.
NNI
A standard interface between two frame relay switches.
N391
Defines how many link integrity polls occur before a full status poll. One out of the number defined in N391 is a full status poll. Default is 6.
N392
Defines how many bad polls can occur within an N393 window before the link is declared down.
N393
Defines the number of polls that make up the window used by N392 to determine if a link is opera- tional.
OSI
Open System Interconnection. It is a standard defined by ISO and the
Packet
A transmission that contains both control information and data.
Packet Endpoint
A virtual port within ATLAS that a specified physical port terminates its data into for further routing by the system.
Packet Switching
A method of routing packets that avoids congestion and minimizes delivery time.
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