ZyXEL Communications omni.net D, Technical Reference

Page: 86 / 186

Technical Reference for ZyXEL omni.net series
7-6
Bandwidth On Demand (BOD)
The function of Bandwidth On Demand (BOD) will monitor the traffic on ISDN links while in
Multilink PPP mode. If there is light traffic on the link, one of the channels will be dropped
automatically. On the other hand, if only one B-channel is used and data traffic is high enough,
BOD will establish the second B-channel to increase the bandwidth of the data link.
The wait for the second B-channel carrier is 60 seconds. If the second B channel can not be
connected successfully the BOD will try again after 60 seconds. If the second call is connected but
negotiation failed, the omni.net will retry three times. If a connection is still not established after the
third try, the Multilink PPP will be disabled automatically.
For BOD, there are four parameters to set high/low threshold and persist time. Traffic utilization is
measured in the ISDN link. Highly compressible data may not generate enough traffic to start the
second B-channel. Both add-persist time and subtract-persist time must be set to activate BOD.
BOD AT Commands Description
ATJAn Add traffic threshold for 'n' K bits per second. 'n' = 48 (default).
ATJSn Subtract traffic threshold for 'n' K bits per second. 'n' = 32 (default)
ATKAmn
Add persist time for 'n' period in 'm' unit, n = 0-127, m = s for seconds and m for
minutes.
ATKSmn Subtract persist time for 'n' period in 'm' unit, n = 0-127, m = s for seconds and m for
minutes.
Table 40. BOD AT Commands
BACP/BAP
Bandwidth Allocation Control Protocol (BACP) and Bandwidth Allocation Protocol (BAP) is used
for call request and link drop under Multilink PPP.
BACP is negotiated during the network phase. Without BACP/BAP, the directory numbers of both
B-channels must be specified before dialing out. In some cases, it is not possible for the ISP to
support more than one chassis that is capable of bundling both channels at the same time. With
BACP/BAP, the second B-channel directory number can be obtained while requesting a call.