
Bandwidth-on-Demand Implementation Notes
117353-B Rev. 00
8-5
• Minimizes the configuration of outgoing phone numbers because only one
number is required. The peer passes other phone numbers to the router, which
the router then uses to make calls.
• Uses call requests to determine whether bandwidth is available, which saves
the cost of placing a call to find out this information.
Call requests are BAP protocol messages and are unrelated to ISDN call
requests. When the router sends a BAP call request, it uses active lines, so
there is no call attempt and no phone charge.
• Ensures that both routers agree to activate and deactivate the lines, so there are
no allocation conflicts.
The Bandwidth Allocation Control Protocol (BACP) is the control protocol. It
negotiates the use of BAP, enabling BAP data to be exchanged between the peer
routers. If BACP negotiation fails, the router will not use BAP for
bandwidth-on-demand service.
How BAP Works
Figure 8-2 shows BAP negotiation between two routers:
Figure 8-2. BAP Negotiation between Two Routers
Router A
Router B
DS0034A
Call request
Router dials
5085551234
Call response
which includes
5085551234
5085551234
5085554365
5085551298
5085559854
Monitor
Non-monitor
Local Phone List
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