edge switch 2/16 service manual Glossary–47
Glossary
static random access memory
SRAM. SRAM is microprocessor-cache random access memory. It is built internal to the
microprocessor or on external chips. SRAM is fast, but relatively expensive (D). Contrast with
dynamic random access memory.
storage area network
SAN. A high-performance data communications environment that interconnects computing
and storage resources so that the resources can be effectively shared and consolidated.
stored addresses
In S/390 mode, a method for configuring addresses.
subnet
A portion of a network that shares a common address component. On transmission control
protocol/Internet protocol (TCP/IP) networks, subnets are defined as all devices whose IP
addresses have the same prefix. Dividing a network into subnets is useful for both security and
performance reasons. IP networks are divided using a subnet mask.
subnet mask
A mask used by a computer to determine whether another computer with which it needs to
communicate is located on a local or remote network. The network mask depends upon the
class of networks to which the computer is connecting. The mask indicates which digits to
look at in a longer network address and allows the router to avoid handling the entire address.
Subnet masking allows routers to move the packets more quickly. Typically, a subnet may
represent all the machines at one geographic location, in one building, or on the same local
area network.
switch
A device that connects, filters and forwards packets between local area network (LAN)
segments or storage area network (SAN) nodes or devices.
switchover
Changing a backup field-replaceable unit (FRU) to the active state, and the active FRU to the
backup state.
switch priority
Value configured into each switch in a fabric that determines its relative likelihood of
becoming the fabric’s principal switch. Lower values indicate higher likelihood of becoming
the principal switch. A value of 1 indicates the highest priority; 225 is the lowest priority. A
value of 225 indicates that the switch is not capable of acting as the principal switch. The value
0 is illegal.
