A broadcast on the local network, looking for the IP address of the destination host. local service

Service where the device supplying the service resides on the same subnet as the device requesting the service.

Local Target Logic (LTL)

A feature of some line modules that assists the EARL in making forwarding decisions. local VLAN

Beneficial for networks whose resources are centralized and in one geographical location. The VLAN can span one switch or many switches within the same floor or building.

logical addressing scheme

The addressing method used in providing manually assigned node addressing. Logical Link Control (LLC)

A sublayer of the Data Link layer of the OSI Reference Model. It provides an interface for the Network−layer protocols and the MAC sublayer; it’s also part of the Data Link layer.

loop

A continuous circle that a packet takes through a series of nodes in a network until it eventually times out. Without a protocol such as STP to detect loops, if no life cycle is assigned to the packet, the data could continuously encircle the network.

loopback plug

A device used for loopback testing. loopback testing

A troubleshooting method used to verify the usability of interfaces. The output and input wires are crossed or shorted in a manner that allows all outgoing data to be routed back into the card.

M−N

management

Fault, capacity, accounting, performance, and security control for a network. Master Communication Processor (MCP)

A feature of the Supervisor Engine that takes commands from the Network Management Processor (NMP) and forwards them to the correct LCP. The MCP is also responsible for testing and configuring the local ports and controlling the ports using LTL and CBL. It also performs diagnostics on the memory, SAINT ASICs, LTL, and CBL. In addition, the MCP is responsible for downloading software to the line modules.

Media Access Control (MAC) address

A six−octet number that uniquely identifies a host on a network. It is a unique number that is burned into the NIC, so it cannot be changed.

Media Access Control (MAC) layer

In the OSI model, the lower of the two sublayers of the Data Link layer. It’s defined by the IEEE as responsible for interaction with the Physical layer.

Media Access Unit (MAU)

IEEE 802.3 specification referring to a transceiver. Not to be confused with a Token Ring MAU (Multistation Access Unit), which is sometimes abbreviated MSAU.

megabit (Mb or Mbit)

One million bits. This term is used to rate transmission transfer speeds (not to be confused with megabyte).

megabyte (MB)

One million transmission bytes. This term usually refers to file size, in which case it would be 1,048,576 bytes.

message

A portion of information that is sent from one node to another. Messages are created at the upper layers of the OSI Reference Model.

microsegmentation

The process of using switches to divide a network into smaller segments.

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