A connection used on the Catalyst 5000 family of switches. It allows as many as seven Ethernet links
to be bundled and load−balanced frame by frame to provide up to 800Mbps of bandwidth. It can
utilize half−duplex or full−duplex links.
Fast Ethernet
IEEE 802.3 specification for data transfers of up to 100Mbps.
fault tolerance
A theoretical concept defined as a resistance to failure. It is not an absolute and can be defined only in
degrees.
fiber channel or fibre channel
A technology that defines full gigabit−per−second data transfer over fiber−optic cable.
Fiber Distributed Data Interface (FDDI)
A high−speed data−transfer technology designed to extend the capabilities of existing LANs using a
dual rotating−ring technology similar to Token Ring.
fiber−optic cable
A physical medium capable of conducting modulated light transmissions. Compared with other
transmission media, fiber−optic cable is more expensive; but it is not susceptible to electromagnetic
interference and is capable of higher data rates. Also known as fiber optics or optical fiber.
File Transfer Protocol (FTP)
The set of standards or protocols that allows you to transfer complete files between different computer
hosts.
Flash memory
A type of memory that keeps its contents (usually the operating system) when the power is cycled.
flow control
A method used to control the amount of data transmitted within a given period of time. There are
different types of flow control. See also dynamic window and static window.
forward delay
The length of time a port will remain in one of four protocol states in Spanning Tree Protocol.
Forwarding Engine (FE)
A major component of ASIC; part of the ClearChannel Architecture on the Cisco Catalyst series 1900
and 2820 switches. It is responsible for learning addresses, allocating buffer space in the shared
memory space, frame queuing, forwarding decisions, and maintaining statistics.
Forwarding Information Base (FIB)
A mirror image of the IP routing table’s routing information, similar to a routing table or information
base. It updates routing information when routing or topology changes occur in the network and
recalculates the next−hop information. The FIB maintains a list of all known routes and eliminates the
need for route cache maintenance associated with fast switching or optimum switching. FIB is used
with the CEF ASIC.
FragmentFree switching
A fast packet−switching method that reads the first 64 bytes of the frame to determine if the frame is
corrupted. If this first part is intact, the frame is forwarded. Also known as Runtless switching.
frame Grouping of information transmitted as a unit across the network at the Data Link layer.
Frame Check Sequence field
A field that performs a cyclic redundancy check (CRC) to ensure that all the frame’s data arrives
intact.
frame filtering
A process useful for VLANs, which utilizes a filtering table to drop frames based on a certain value
contained in any one of the many fields in the data frame, such as the source or destination address.
As part of normal operations, switches share filter tables. The frame’s contents are compared to the
filter table in the switch, thereby increasing the latency of the switch. Frame filtering is not used to
implement VLANs in the Cisco Catalyst 5000 or 6000 family of switches.
Frame Length field
In a data frame, the field that specifies the length of a frame. The maximum length for an 802.3 frame
is 1,518 bytes.
Frame Relay
381