A-B

Ack

Another name for Acknowledgement. Sent by a receiver of a packet to the sender.

action routines

The part of a state machine which implements the action for a specific event in a specific state. Action routines may be shared, so you could have the same action routine invoked for several state–event combinations.

agent

A software entity on the embedded device which processes and responds to manager requests. An SNMP agent is one example.

AgentX

Agent Extensibility as defined by RFC 2741 from the IETF. The architecture defines a master agent, which processes SNMP messages, and one or more subagents, which interact with the master agent for management operations. The subagents do not need to deal with SNMP; they use only the AgentX protocol to interact with the master agent.

ANSI

American National Standards Institute. A private body based in the US which specifies its own standards. The body also participates in ISO standardization activities.

API

Application Programming Interface. The specification of the services provided by a module for use by other modules, including the method of invoking the services.

ARP

Address Resolution Protocol. A protocol used in the IP world to determine the IP address–to–MAC address mapping.

ASIC

Application Specific Integrated Circuit. A custom IC for a specific function. ASICs are usually designed internally for a specific product. They are expensive to design but are optimized for the required function.

ATM

Asynchronous Transfer Mode. A cellbased, connection-oriented technology with 53-byte cells.

authentication

The method of verifying the sender of a message.

backplane

A hardware interconnect in multiboard systems that which individual cards plug into. Each card or blade communicates with other cards over this interconnect.

basic parameters

The minimum set of parameters required to configure a protocol/device. These parameters cannot take default values and need to be explicitly configured.

BGP

Border Gateway Protocol. An exterior gateway protocol used for exchanging routes in the Internet.

blocking call

A function call which does not return until the complete operation is performed in the implementation. The call waits or “blocks” until the operation is performed. An example is a call to receive a packet, which does not return until the packet is actually received.

board support package (BSP)

A port of a Real Time Operating System to a specific hardware board. The package will include processor-specific code, including initialization, checks for the DRAM and other devices on the board, and hooking up to timers. The BSP for several COTS boards are provided by the RTOS vendor.

bps

Bits per second.

bridge

A Layer 2 device which learns the location of nodes in its connected LANs by using the source address from received frames. A variation of the bridge is the Layer 2 switch, which can provide bridging between multiple independent ports at the same time, often using hardware support.

broadcast address

A destination address value which indicates that the packet is to be delivered to all addresses in the network.

buffer

A temporary memory block used to store data during processing. It is used to transport payload and control information within a communications device.

buffer management

The techniques used to handle the allocation, freeing, manipulation, and control of buffers in the system.