C

caching

A method that uses a temporary memory block or area to store recently used information.

CAM

Content Addressable Memory. A memory mechanism in which a search is done in parallel across all locations in the memory.

chained buffer

A buffer which exists as part of a linked list of buffers. The entire buffer chain is used to house a single packet.

checkpointing

A technique used to indicate the current state and configuration of a primary system to its peer redundant system. If the primary system fails, the redundant system can proceed with the information from the last checkpoint.

checksum

An integer value used to verify that the packet is uncorrupted.

chipset

Two or more integrated circuits designed to work together.

circuit switch

A switching technique in which a dedicated circuit is established between source and destination.

CLI

Command Line Interface. A text-based user interface for configuring and controlling a device. Also known as Man- Machine Interface (MMI).

conformance testing

Testing done to indicate that the product conforms to standards. Protocol conformance is one type of conformance. A protocol like PPP can be tested for conformance to the various PPP RFCs.

connection oriented

A method which requires the setting up of a connection between two nodes before traffic can be sent between them. TCP is an example of a connection-oriented protocol.

connectionless

A method which does not require the setting up of a connection between nodes for data traffic. Each packet contains the address of the destination node. IP and UDP are examples of connectionless protocols.

context switch

An operating system action which causes the suspension of the currently executing task and begins the execution of another task. The context switch takes a finite amount of time due to the saving of one context (program counter, stack and contents of registers) and loading of another.

control block

An anchor or root data structure used to access all the other information related to a protocol, interface, or infrastructure software module, including configuration, control, status, and statistics. A control block can be used in other contexts, say, for a protocol (PCB), hardware interface (HICB), or protocol interface (PICB).

control card

A hardware board in a multi- board system which runs the control protocols to communicate with peers and construct tables for use by the line cards.

control plane

In the classical planar networking architecture model, this is the function which communicates with peer entities to build up tables for use by the data plane. Protocols like UNI 4.0 ATM Signaling and OSPF are in the control plane.

controller

A hardware device to perform the specific functions required for a network interface, e.g., an Ethernet controller.

CORBA

Common Object Request Broker Architecture. An architecture specified by the Object Management Group (OMG) for distributed object representation and utilization.

COTS

Common Off The Shelf. Typically used to describe hardware or boards which are available from vendors without any need for custom development.

CRC

Cyclic Redundancy Check. Inserted as a verifier by the sender into a frame. The value is calculated on the data in the frame. The receiver verifies the integrity of the transmission by calculating its own CRC on the received frame and comparing it with the CRC in the frame.