D-12
Cisco ONS 15454 Installation and Operations Guide
November 2001
AppendixD Glossary
Static route
A route that is manually entered into a routing table. Static routes take precedence over routes chosen
by all dynamic routing protocols.
STP
Spanning Tree Protocol. Bridge protocol that uses the spanning-tree algorithm to enable a learnin g
bridge to dynamically work around loops in a network topology by creating a spanning tree. Se e also
Spanning tree, STA, and Learning bridge.
STS-1
Synchronous Transport Signal 1. Basic building block signal of SONET, operating at 51.84 Mbp s f or
transmission over OC-1 fiber. Faster SONET rates are defined as STS-n, where n is a multiple of 51.84
Mbps. See also SONET.
Subnet mask
32-bit address mask used in IP to indicate the bits of an I P address that are used for the subnet address.
Sometimes referred to simply as mask. See also IP address mask and IP address.
Subnetwork
In IP networks, a network confined to a particular subnet address. Subnetworks are networks segmented
by a network administrator in order to provide a multilevel, hierarchical routing structure whil e shielding
the subnetwork from the addressing complexity of attached networks. Sometimes called a subnet.
Subtending rings
SONET rings that incorporate nodes that are also part of an adjacent SONET ring.
Superuser
A security level that can perform all of the functions of the other security levels as well as set names,
passwords, and security levels for other users. A superuser is usually the network element adm inistrator.
See also Retrieve user, Maintenance user, and Provisioning user.
T
T1
T1 transmits DS-1-formatted data at 1.544 Mbps through the tel epho ne -swi tchin g n etwor k using A MI
or B8ZS coding. See also AMI, B8ZS, and DS-1.
Tag
Identification information, including a number plus other information.
TDM
Time Division Multiplexing. Allocates bandwidth on a single wire for information from multiple
channels based on preassigned time slots. Bandwidth is allocated to eac h channel regardless of whether
the station has data to transmit.