Motorola 3260FAST User Manual page 90

Bandwidth On Demand
Bandwidth on demand is often required to support sporadic peak loads. With the
SDC modem, you can ensure full network availability and performance at low dial-
up line costs, without having to prioritize users or applications.
Figure 4-4 shows a point-to-point digital link with Motorola 35XX DSU/CSUs
connecting two routers over a DDS circuit. The SDC modems are also connected
directly to the routers. During peak network access periods, the router is configured
to signal the SDC modem to establish a dial connection through the PSTN. Users
transparently bypass the digital link, using the 326XFAST-SDC PSTN link to
continue data transmission. As bandwidth demands subside, the dial call is dropped,
and transmission resumes over the DDS link.
The SDC modem supports all industry-standard ACUs (AT, V.25bis, DTR dialing,
and LPDA-2). Bandwidth on demand can be initiated/terminated under the control of
the nodal equipment by a secondary port. NOTE: Nodal equipment must be
configured for secondary port restoral/bandwidth on demand operation. Refer to the
nodal equipment documentation for instructions on configuring for this application.
Select SDC Option Set 3 for a bandwidth on demand application. All operational
information described in the preceding section, "SDC Option Set 3—Sync Dial
Only", applies to this application.
To 33.6 kbps
PSTN
326XFAST 326XFAST
SDC SDC
To
56 kbps
56 kbps
Router Router
35XX 35XX
Network Management Channel
NMS
Figure 4-4. Bandwidth On Demand—Option Set 3
Configuring the Modem 4-27
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