Cisco Systems RJ-45-to-AUX manual 378

A feature of the SAMBA ASIC used to cause the EARL to make forwarding decisions. It also ensures that a tagged frame that comes from a particular VLAN does not exit through a port belonging to another VLAN. CBL also assists in placing ports in one of four different modes for Spanning−Tree Protocol: blocking, learning, listening, or forwarding.

common carrier

A supplier of communications utilities, such as phone lines, to the general public. communication

The transfer of information between nodes on a network. connection−oriented communication

Packet transfer in which the delivery is guaranteed. connectionless communication

Packet transfer in which the delivery is not guaranteed. connectivity

The linking of nodes on a network in order for communication to take place. Content Addressable Memory (CAM)

A table used by a bridge to make forwarding and filtering decisions. The CAM table contains MAC addresses with port addresses leading to the physical interfaces. The CAM table uses a specialized interface that is faster than RAM to make forwarding and filtering decisions. It examines frames it receives from a segment and then updates the table with the source MAC address from the frame.

control plane

Functions that dictate how data actually flows through the switching fabric. Copper Distributed Data Interface (CDDI)

The implementation of the FDDI standard using electrical cable rather than optical cable. Core block

The end point for networks. It requires fast access and no policy implementation. Core layer

In the Cisco Hierarchical Model, the backbone of the network, designed for high−speed data transmission.

crosstalk

Electronic interference caused when two wires get too close to each other. cut−through packet switching

A switching method that does not copy the entire packet into the switch buffers. Instead, the destination address is placed in buffers, the route to the destination node is determined, and the packet is quickly sent out the corresponding port. The switch begins forwarding the frame as soon as the first 13 bytes and MAC address are received. It relies on the receiving device to discard the frame if there is corruption. Cut−through packet switching maintains a low latency.

cyclical redundancy check (CRC)

A method used to check for errors in packets that have been transferred across a network. A computation bit is added to the packet and recalculated at the destination to determine if the entire packet contents have been transferred correctly.

D

D connectors

Connectors shaped like the letter D that use pins and sockets to establish connections between peripheral devices using serial or parallel ports. The number that follows is the number of pins the connector uses for connectivity. For example, a DB−9 connector has 9 pins, and a DB−25 has 25 pins.

data field

In a frame, the field or section that contains the data. Data Link layer

Layer 2 of the OSI Reference Model. The Data Link layer is above the Physical layer. Data comes off the cable, through the Physical layer, and into the Data Link layer.

data plane

Functions applied directly against the actual data being directed in and out of the switching fabric.

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