Download Combined (Dual) Mode Commands

Applications and Use
VT1.5 Channel Scan—ADM and E-DCS Testing
Figure 5–4 VT1.5 Structures
SONET (Synchronous Optical Network) can carry large payloads (above 50 Mb/s) on most of
the existing digital hierarchy signaling equipment. To achieve this capacity the Synchronous
Transport Signal (STS) has a Synchronous Payload Envelop (SPE) that is divided into smaller
components, shown in Figure 5–4, known as Virtual Tributaries (VT). They are used for the
purpose of transporting and switching payloads smaller than the STS-1 rate (51.84 Mb/s), for
example, asynchronous services below the DS3 rate (45 Mb/s).
Figure 5–5 VT1.5 Channel Configuration (VFP) Menu, Transmitter
Routing and provisioning can be verified off-line because the Test Set can encode valid data into
all 28 VT1.5 channels and user selected data into anyone of them. Figure 5–5 shows that channel
1 has been selected for user selected data, and that 4x7 channel numbering is being used. The
4x7 mapping is selected if the terminal consists of seven line cards, each having four channels.
The 1x28 mapping is used for configurations having one or more line cards with sequential
numbered channels.
ST112 SONET Transmission Test Set
5–5
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