Glossary
Issue 8.0 July 2002
GL-19
Source Node
The source node is the node in a ring where the low speed signals on an STS-3 tributary originate.
The source node and destination node of an STS-3 tributary are always in the same ring. Also see
Destination Node.
SPE
Synchronous Payload Envelope — A 125-microsecond frame structure composed of STS path
overhead and bandwidth for the payload.
Squelch Map
A map (table) containing information for each cross connection in the ring and indicates the source
and destination nodes for the low speed circuit that define the cross connection. This information is
used to prevent traffic misconnection in rings with isolated nodes or arguments. (This term is some-
times referred to as "Ring Squelch Map").
Squelching
To avoid misconnected traffic when performing a 2-fiber ring protection switch, the ^FT-2000 OC-48
Add/Drop-Rings Terminal inserts STS-1 path AIS on protection tributaries for traffic that cannot be
terminated because of node failures or multiple failures in the ring. Squelching is only performed by
nodes that have an active protection switch.
Standby
Standby refers to a 1+1 protected OC-3 line that is not currently selected by the receiving terminal
at either end as the payload carrying signal. (Also refer to Active.)
Status
Status is a condition that does not raise an alarm.
STS, STS-n
Synchronous Transport Signal — The basic logical building block signal with a rate of 51.840 Mb/s
for an STS-1 signal and a rate of n times 51.840 Mb/s for an STS-n signal.
STS-1
This refers to the FT-2000 OC-48 Add/Drop-Rings Terminal internal electrical signal with an
EC-1 format.
STS-1E
The FT-2000 OC-48 Lightwave System STS1 Electrical Interface circuit pack interfaces with up to
three bidirectional EC-1 signals.
STS-1 Granularity
In Release 7 and later releases, the FT-2000 OC-48 Add/Drop-Rings Terminal has an STS-1 time
slot assignment capability that allows any service STS-1 tributary to be cross-connected to any ser-
vice low speed port or to the same-numbered service STS-1 tributary in the opposite direction.
STS-1 Group
Three STS-1 signals in the same STS-3 signal.
Subnetwork
SONET networks with data communications channel connectivity. When Release 6 of the FT-2000
OC-48 Add/Drop-Rings Terminal interworks with Release 7.2 or Release 9 of the DDM-2000 OC-3
Multiplexer, the recommended maximum subnetwork size is 24 network elements. In Release 7 and
later releases, the recommended maximum subnetwork size is 32 network elements.
Sync Messaging
A method whereby nodes within a FT2000 ring communicate their synchronization status with
other nodes in the ring.
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