Glossary
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flow
A shortcut or MLS cache entry that is defined by the packet proper-
ties. Packets with identical properties belong to the same flow. See also: MLS.
flow control
A methodology used to ensure that receiving units are not
overwhelmed with data from sending devices. Pacing, as it is called in IBM
networks, means that when buffers at a receiving unit are full, a message is
transmitted to the sending unit to temporarily halt transmissions until all the
data in the receiving buffer has been processed and the buffer is again ready
for action.
FRAD
Frame Relay Access Device: Any device affording a connection
between a LAN and a Frame Relay WAN. See also: Cisco FRAD and FRAS.
fragment
Any portion of a larger packet that has been intentionally seg-
mented into smaller pieces. A packet fragment does not necessarily indicate
an error and can be intentional. See also: fragmentation.
fragmentation
The process of intentionally segmenting a packet into
smaller pieces when sending data over an intermediate network medium that
cannot support the larger packet size.
FragmentFree
LAN switch type that reads into the data section of a frame
to make sure fragmentation did not occur. Sometimes called modified cut-
through.
frame
A logical unit of information sent by the Data Link layer over a
transmission medium. The term often refers to the header and trailer,
employed for synchronization and error control, that surround the data con-
tained in the unit.
Frame Relay
A more efficient replacement of the X.25 protocol (an unre-
lated packet relay technology that guarantees data delivery). Frame Relay is
an industry-standard, shared-access, best-effort, switched Data Link layer
encapsulation that services multiple virtual circuits and protocols between
connected mechanisms.
Frame Relay bridging
Defined in RFC 1490, this bridging method uses
the identical spanning-tree algorithm as other bridging operations but per-
mits packets to be encapsulated for transmission across a Frame Relay
network.
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