Micrel, Inc.
KSZ8851SNL/SNLI
August 2009
79
M9999-083109-2.0
Acronyms and Glossary
BIU
Bus Interface Unit
The host interface function that performs code conversion,
buffering, and the like required for communications to and from a
network.
BPDU
Bridge Protocol Data Unit
A packet containing ports, addresses, etc. to make sure data
being passed through a bridged network arrives at its proper
destination.
CMOS
Complementary Metal Oxide Semiconductor
A common semiconductor manufacturing technique in which
positive and negative types of transistors are combined to form a
current gate that in turn forms an effective means of controlling
electrical current through a chip.
CRC
Cyclic Redundancy Check
A common technique for detecting data transmission errors. CRC
for Ethernet is 32 bits long.
Cut-through Switch
A switch typically processes received packets by reading
in the full packet (storing), then processing the packet to determine
where it needs to go, then forwarding it. A cut-through switch
simply reads in the first bit of an incoming packet and forwards the
packet. Cut-through switches do not store the packet.
DA
Destination Address
The address to send packets.
DMA
Direct Memory Access
A design in which memory on a chip is controlled independently of
the CPU.
EEPROM
Electronically Erasable Programmable
A design in which memory on a chip can be erased by
Read-only Memory
exposing it to an electrical charge.
EISA
Extended Industry Standard Architecture
A bus architecture designed for PCs using 80x86 processors, or
an Intel 80386, 80486 or Pentium microprocessor. EISA buses
are 32 bits wide and support multiprocessing.
EMI
Electro-Magnetic Interference
A naturally occurring phenomena when the electromagnetic field
of one device disrupts, impedes or degrades the electromagnetic
field of another device by coming into proximity with it. In computer
technology, computer devices are susceptible to EMI because
electromagnetic fields are a byproduct of passing electricity
through a wire. Data lines that have not been properly shielded
are susceptible to data corruption by EMI.
FCS
Frame Check Sequence
See CRC.
FID
Frame or Filter ID
Specifies the frame identifier. Alternately is the filter identifier.
IGMP
Internet Group Management Protocol
The protocol defined by RFC 1112 for IP multicast transmissions.
IPG
Inter-Packet Gap
A time delay between successive data packets mandated by the
network standard for protocol reasons. In Ethernet, the medium
has to be "silent" (i.e., no data transfer) for a short period of time
before a node can consider the network idle and start to transmit.
IPG is used to correct timing differences between a transmitter
and receiver. During the IPG, no data is transferred, and
information in the gap can be discarded or additions inserted
without impact on data integrity.
ISI
Inter-Symbol Interference
The disruption of transmitted code caused by adjacent pulses
affecting or interfering with each other.
ISA
Industry Standard Architecture
A bus architecture used in the IBM PC/XT and PC/AT.
Jumbo Packet
A packet larger than the standard Ethernet packet (1500 bytes).
Large packet sizes allow for more efficient use of bandwidth, lower
overhead, less processing, etc.
MDI
Medium Dependent Interface
An Ethernet port connection that allows network hubs or switches
to connect to other hubs or switches without a null-modem, or
crossover, cable. MDI provides the standard interface to a
particular media (copper or fiber) and is therefore 'media
dependent.'