D-Link DI-308 - Manual (Page 82)

DI-308 ISDN Remote Router
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Bandwidth on Demand – Enables or disables BOD. When enabled, BOD will
manage the implementation of MLPPP using the parameters defined in this
window.
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BOD Criteria – TX, RX, or TX or RX, where TX is Transmit and RX is Receive.
The parameter defined here is used when monitoring the BOD High Threshold
and BOD Low Threshold.
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BOD High Threshold (%) – (0 to 100) The throughput value as a percentage of
total bandwidth which will cause the next ISDN port having Multi-Link PPP
enabled to dial up and add bandwidth to the connection. This value, however,
must be constantly exceeded for the time designated in the Add Bandwidth Delay
field before the next ISDN port dials out.
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BOD Low Threshold (%) – (0 to 100) The throughput value as a percentage of
total bandwidth which will cause the highest numbered ISDN port in the MLPPP
bundle to hang up, thus subtracting bandwidth from the connection. Before
actually hanging up however, the throughput must be below this value for the
time designated in the Subtract Bandwidth Delay field.
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Add Bandwidth Delay (sec) – (0 to 300) The amount of time in seconds the
router will wait and sample the BOD Criteria before adding bandwidth once the
throughput exceeds the BOD High Threshold. This prevents costly bandwidth
from being unnecessarily added due to temporary bursts in traffic.
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Subtract Bandwidth Delay (sec) – (0 to 300) The amount of time in seconds the
router will wait and sample the BOD Criteria before subtracting bandwidth once
the throughput falls below the BOD Low Threshold. This prevents bandwidth
from being unnecessarily subtracted due to temporary lulls in traffic.
The example Multi-link PPP settings shown in the Multi-Link PPP Configuration
window above assumes that ISDN 1 and ISDN 2 each have a 64 kbps connection
configured to dial up to the Internet. When ISDN 1 receives a packet destined for the
Internet it will dial the ISP and establish a connection. If the total throughput on
ISDN 1 (TX or RX) ever exceeds 80% of the 64 kbps (51.2 kbps), the router will
sample the line for an additional 5 seconds. If the traffic continuously exceeds 80%
for the 5 second delay time, ISDN 2 will dial up and add bandwidth to the
connection. Assuming sustained traffic of 70 kbps, MLPPP will balance the traffic
on the two ISDN ports so they are handling roughly 35 kbps each. If the traffic on
ISDN 1 + ISDN 2 falls below 20% of the 128 kbps connection (25.6 kbps) for more
than 10 seconds, ISDN 2 will hang up and all traffic will be handled by ISDN 1.
For the above configuration to work, both ISDN ports need to have been properly set
up to establish dial-out PPP connections, and have Multi-Link enabled. Also note
that ISDN 1, being the B-channel that initiated the call in the MLPPP bundle and
thus the primary link, is not subject to the BOD Low Threshold parameter and will
never hang up due to BOD considerations. The primary link can, however, be
subject to Dial on Demand (DOD) settings, and could thus disconnect if Dial on