DBA Data Protocols

PPP/MLPPP

If an outgoing analog call is desired or there is an incoming analog call, a data channel can be bumped (removed) to allow analog POTS port use.

Bandwidth-on-Demand (BOD) checks the data throughput to determine whether a channel should be added or removed.

Call Bumping (CB) determines whether a channel needs to be added again (analog call disconnected) or removed (incoming or outgoing analog call desired) due to activity on the analog POTS port.

To activate Bandwidth-on-Demand or Call Bumping, enable Dynamic Bandwidth Allocation in S-register S59.

The 128 LED flashes if DBA is active and only one data channel is connected. The 128 LED stops flashing and remains on after the second B-channel is successfully added. If the second channel is disconnected due to low throughput or a call-bump, the 128 LED flashes again to indicate that DBA is still active.

If the TA attempts to add a B-channel, but the host is busy or not answering, the TA starts a timer (time is set in S-register S31). However, if the analog device goes off-hook or an analog call is received, the timer is stopped and reset. After the analog call finishes, the TA again attempts to add the B-channel. Taking the analog device off-hook and placing it on-hook again interrupts the timer, thus allowing control over the amount of time it takes before attempting to add the second channel (rather than waiting for timeout values specified by S31).

MLPPP is the only data protocol that currently supports DBA. To start DBA, set &J1 or give two numbers to be dialed. Otherwise, the TA will not negotiate the MultiLink Protocol (MP) option. If the MultiLink Protocol option is not negotiated, Dynamic Bandwidth Allocation is not possible.

DBA Features:

Bandwidth-on-Demand (BOD)—S60, S61, S62, and S63

•Bandwidth-on-Demand (BOD) is not available to the host TA if Dynamic Bandwidth Allocation is disabled (S59=0) or if the Dynamic Bandwidth Allocation scheme is PPP (S59=2).

•Setting S60=0 disables the BOD feature completely (meaning S61, S62, and S63 are disabled as well).

•To calculate High Throughput Average (in Kbps):

–Divide the total number of bits received from the PC (not including start, stop, or parity bits) during the High Threshold Sampling Period (S60) by the High Threshold Sampling Period (S60) value (in Kbps).

Total bits received S60 = High Throughput Average

–Or, divide the total number of bits transmitted to the PC (don’t include start, stop, or parity bits) during the High Threshold Sampling Period (S60) by the High Threshold Sampling Period (S60) value (in Kbps).

Total bits transmitted S60 = High Throughput Average

If the average (transmitted or received) exceeds the High Threshold (S61) and only one data channel is active and the second B-channel is not already in use, the TA attempts to add a second data channel.

•To calculate Low Throughput Average (in Kbps):

–Divide total number of bits received from the PC (not including start, stop, or parity bits) during the Low Threshold Sampling Period (S62) by the Low Threshold Sampling Period (S62) value (in Kbps).

Total bits received S62 = Low Throughput Average

–Or, divide total number of bits transmitted to the PC (not including start, stop, or parity bits) during the Low Threshold Sampling Period (S62) by the Low Threshold Sampling Period (S62) value (in Kbps).

Total bits transmitted S62 = Low Throughput Average

If either average (transmitted or received) equals or is less than the Low Threshold (S63) and there are two active data channels, the TA disconnects the second data channel.

•Ideally, the second channel should be added quickly (short High Threshold Sampling Period [S60] with a relatively small High Throughput Threshold [S61]). Also, the second channel should not be disconnected

MTA128ST/NT