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Wireless Networking Glossary
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L
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| L1 | Layer 1 |
| L2 | Layer 2 |
| L2TP | Layer 2 Tunnel Protocol. Defined in RFC 2661. Successor to PPTP. IP packets are wrapped in a layer containing another set of IP addresses and possibly also control messages. The detailed format varies depending on whether the transport protocol is IP, UDP or another PSN type. |
| L3 | Layer 3 |
| LAC | Link Access Control |
| LAN | Local Area Network. Group of computers and associated devices that share common communications line or wireless link and typically share the resources of a single processor or server within a small geographic area (for example, within an office building). |
| LAP | Link Access Protocol |
| LAPB | Link Access Protocol, Balanced |
| LAPD | Link Access Protocol for the ISDN D Channel |
| Last-mile technology | Telecommunications technology at neighborhood level. Any telecommunications technology, such as wireless radio that carries broad telecommunication signals along relatively short distance ("last mile") to and from homes, businesses. |
| LATA | Local Access and Transport Area. US local telephone service area |
| Layer 1 | Operation mode for access concentrator; physical layer. Conveys bit stream through network at electrical and mechanical level. Provides hardware means of sending and receiving data on a carrier. See OSI. |
| Layer 2 | Operation mode for access concentrator; data-link layer. Provides synchronization for physical level and does bit stuffing for strings of 1's in excess of 5. Furnishes transmission protocol knowledge and management. Frame Relay prioritization layer. See OSI. |
| Layer 3 | Operation mode for access concentrator; network layer. Handles routing of data (sending it in right direction to right destination on outgoing transmissions; receiving incoming transmissions at packet level). Does routing and forwarding. IP ToS prioritization mode. |
| Layer 4 | Operation mode for access concentrator; transport layer. Manages end-to-end control (for example, determining whether all packets have arrived) and error checking. Ensures complete data transfer. Allows for policy-based switching (for example, limiting different types of traffic on specific end-user switch ports, or for prioritizing certain packet types, such as database or application server traffic). See OSI. |
| Layer 5 | Operation mode for access concentrator; session layer. Sets up, coordinates, and terminates conversations, exchanges, and dialogs between applications at each end. Deals with session and connection coordination. See OSI. |
| Layer 6 | Operation mode for access concentrator; presentation layer. Usually part of operating system, converts incoming/outgoing data from one presentation format to another. A.k.a. syntax layer. See OSI. |
| Layer 7 | Operation mode for access concentrator; application layer. Layer at which communication partners are identified, quality of service is identified, user authentication and privacy are considered and any constraints on data syntax are identified. See OSI. |
| LDAP | Lightweight Directory Access Protocol. See IETF RFC 3377. Compare with X.500 DAP |
| LEC | Local Exchange Carrier (wireline carrier for local calls). Also see ILEC and CLEC |
| LIFO | Last in, first out. A queuing methodology similar to stacking dishes and using the dish on the top of the stack. Compare with FIFO |
| LLC Layer | Logical Link Control Layer. One of two sub-layers of Layer 2 Data-Link layer; controls frame synchronization, flow control and error checking. |
| LMDS | Local Multipoint Distribution Service. Uses the 27.5-31.3 GHz frequency band to serve mulitple points within a radius of 3-5km. Most carriers in this space have abandoned it or gone bankrupt. See MMDS. |
| Loopback support | Test signal sent to network destination that is returned as received to originator. Returned signal may help diagnose problem. |
| LOS | Line of Sight. A direct path through the air from transmitter to receiver. Always desirable for wireless communications, although not always necessary (e.g. for cellular/PCS) |
| LSB | Least Significant Bit or Byte. Compare with MSB |
| LSMS | Local Service Management System. Telephone carrier interface that downloads information from the NPAC into one or more NPDBs |