Specifications

Glossary
GL-11
Cisco ONS 15454 Installation and Operations Guide, R3.2
March 2002
SPE
Synchronous Payload Envelope. A SONET term describing the envelope that carries the user data or payload.
SSM
Sync Status Messaging. A SONET protocol that communicates information about the quality of the timing source using the S1
byte of the line overhead.
STA
Spanning-Tree Algorithm. An algorithm used by the spanning tree protocol to create a spanning tree. See also Spanning tree
and STP.
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 learning bridge to dynamically work
around loops in a network topology by creating a spanning tree. See also Spanning tree, STA, and Learning bridge.
STS-1
Synchronous Transport Signal 1. Basic building block signal of SONET, operating at 51.84 Mbps for 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 IP 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 while 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 administrator. See also Retrieve user, Maintenance user, and
Provisioning user.
T
T1
T1 transmits DS-1-formatted data at 1.544 Mbps through the telephone-switching network using AMI or B8ZS coding. See
also AMI, B8ZS, and DS-1.