Specifications

Glossary
GL-6
Cisco ONS 15454 Installation and Operations Guide, R3.2
March 2002
Host number
Part of IP address used to address an individual host within the network or subnetwork.
Hot swap
The process of replacing a failed component while the rest of the system continues to function normally.
I
Input alarms
Used for external sensors such as open doors, temperature sensors, flood sensors, and other environmental conditions.
IP
Internet Protocol. Network layer protocol in the TCP/IP stack offering a connectionless internetwork service. IP provides
features for addressing, type-of-service specification, fragmentation and reassembly, and security.
IP address
32-bit address assigned to host using TCP/IP. An IP address belongs to one of five classes (A, B, C, D, or E) and is written as
4 octets separated by periods (dotted decimal format). Each address consists of a network number, an optional subnetwork
number, and a host number.
K
K bytes
Automatic protection switching bytes. K bytes are located in the SONET line overhead and monitored by equipment for an
indication to switch to protection.
L
LAN
Local Area Network. High-speed, low error data network covering a relatively small geographic area. LANs connect
workstations, peripherals, terminals, and other devices in a single building or other geographically limited area. Ethernet,
FDDI, and Token Ring are widely used LAN technologies.
LCD
Liquid Crystal Display. An alphanumeric display using liquid crystal sealed between two pieces of glass. LCDs conserve
electricity.
Line layer
Refers to the segment between two SONET devices in the circuit. The line layer deals with SONET payload transport, and its
functions include multiplexing and synchronization. Sometimes called a maintenance span.
Line timing mode
A node that derives its clock from the SONET lines.