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Glossary
GL-12
Cisco 10008 Router Hardware Installation Guide
OL-0659-13
Simple Network
Management
Protocol
See SNMP.
Single-mode fiber
See SMF.
SMF
Single-mode fiber. Fiber-optic cabling with a narrow core that allows light to enter only at a single
angle. Such cabling has higher bandwidth than multimode fiber, but requires a light source with a
narrow spectral width (for example, a laser). Also called monomode fiber. See also Multimode fiber.
SNMP
Simple Network Management Protocol. Network management protocol used almost exclusively in
TCP/IP networks. SNMP provides a means to monitor and control network devices, and to manage
configurations, statistics collection, performance, and security. See also SNMP2.
SNMP2
SNMP Version 2. Version 2 of the network management protocol. SNMP2 supports centralized as well
as distributed network management strategies, and includes improvements in the SMI, protocol
operations, management architecture, and security. See also SNMP.
SONET
Synchronous Optical Network. High-speed synchronous network specification developed by Bellcore
and designed to run on optical fiber. STS-1 is the basic building block of SONET. It was approved as
an international standard in 1988.
SR
Short reach. SONET/SDH specification for transmit power and receive sensitivity that achieves a
1.2-mile (2 km) reach.
SRAM
A type of RAM that retains its contents for as long as power is supplied. SRAM does not require
constant refreshing, like DRAM. Compare with DRAM.
Subrate DS3
A generic term to describe a process in which the bandwidth of a clear channel DS3 is limited to a lower
rate. Several proprietary formats exist.
Synchronous
Optical Network
See SONET.
T
T1
Digital WAN carrier facility. T1 transmits DS1-formatted data at 1.544 Mbps through the telephone
switching network.
T3
Digital WAN carrier facility. T3 transmits DS3-formatted data at 44.736 Mbps through the telephone
switching network.
TAC
A Cisco Technical Assistance Center. There are four TACs worldwide.
TACACS
Terminal Access Controller Access Control System. Authentication protocol, developed by the DDN
community, that provides remote access authentication and related services, such as event logging.
User passwords are administered in a central database rather than in individual routers, providing an
easily scalable network security solution.
TACACS+
Terminal Access Controller Access Control System Plus. Proprietary Cisco enhancement to Terminal
Access Controller Access Control System (TACACS). Provides additional support for authentication,
authorization, and accounting.