Animated Optical Glossary
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EXFO Glossary

L (browse from .......... to)
L_Port...............LEDLegacy...............Logical Link Control (LLC)LOH...............LSRLTE...............LUG
L_PortLatencyLayer 6
Label-Switched Path (LSP)Layer 1Layer 7
LANLayer 2LCAS
LAPSLayer 3LCK
LaserLayer 4Leased Line
Laser DiodeLayer 5LED
Last MileLayer 5
 
from L_Port... to LED

L_Port

Acronym for: Loop port


Label-Switched Path (LSP)

A path through an MPLS network, set up by a signaling protocol such as LDP, RSVP-TE, BGP or CR-LDP. The path is set up based on criteria in the forwarding equivalence class (FEC).



LAPS

Acronym for: Link access procedure for SDH


Laser

Term that was originally an acronym for “light amplification by stimulated emission of radiation”. A laser usually consists of a light-amplifying medium placed between two mirrors. Light not perfectly aligned with the mirrors escapes from the sides, but light perfectly aligned will be amplified. As one mirror is made partially transparent, the result is an amplified beam of light that emerges through the partially transparent mirror.


Laser Diode

A semiconductor laser used for signal transmission in fiber optics. The diode emits a high powered light through a glass lens to minimize signal loss.



Latency

In an Ethernet-based network, latency is defined as the time elapsed since the start of transmission of the first bit of the frame by a source node until the reception of the last bit of the same frame by the destination node.


Layer 1

In the seven-layer OSI model, it is the physical layer. The physical layer consists of the basic networking transmission technologies of a network.


Layer 2

In the seven-layer OSI model, it is the data link layer. The data link layer is the protocol layer that transfers data between adjacent network nodes.


Layer 3

In the seven-layer OSI model, it is the network layer. The network layer is responsible for packet forwarding including routing through intermediate routers, whereas the data link layer is responsible for media access control, flow control and error checking.


Layer 4

In the seven-layer OSI model, it is the transport layer. The transport layer provides end-to-end or host-to-host communication services for applications within a layered architecture.


Layer 5

In the seven-layer OSI model, it is the session layer. The session layer provides the mechanism for opening, closing and managing a session between end-user application processes. This layer is not used in modern communication networks.


Layer 5

In the seven-layer OSI model, it is the session layer. The session layer provides the mechanism for opening, closing and managing a session between end-user application processes. This layer is not used in modern communication networks.


Layer 6

In the seven-layer OSI model, it is the presentation layer. The presentation layer serves as the data translator for the network.  It is sometimes called the syntax layer. This layer is not used in modern communication networks.


Layer 7

In the seven-layer OSI model, it is the application layer. In the Internet model, the application layer is an abstraction layer reserved for communications protocols and methods designed for process-to-process communications across an Internet Protocol (IP) computer network. Application layer protocols use the underlying transport layer protocols (Layer 4) to establish process-to-process connections via ports.



LCK

Acronym for: Locked


Leased Line

A dedicated circuit (private telephone line) between two locations. A leased line is available full time for transmission of data or voice.