Dynamic Bandwidth Allocation - ZyXEL Communications Omni TA128 User Manual

Chapter 8 - X.75 ISDN Communications
1TR6) then it is deemed as a bundle request. The two data calls are established following
normal call control procedures. That is, the network treats them as two independent calls.
The TAs in the two sites then use X.75 Multiple Link Protocol or 'cFos' channel
bundling protocol to coordinate the two B channels. The former would need an
overhead of two octets for each packet. The success of bundle connection initiation is
indicated by the connect message reported to DTE as follows:
CONNECT 460800 / X.75M 128K / V42b
If any B channel is unavailable in any site then the bundle initiation will fall back to single
channel connection. In this case the connect message may be as follows:
CONNECT 460800 / X.75 64000 / V42b
Dialing Pre-stored Phone Numbers
The 40 phone numbers stored in the NVRAM can also be used to placing a bundle call.
Use ATDSn, (n=0-39), to dial the (n+1)th phone number twice for both the bundle
connections.
Use ATDSn+, (n=0-38), to dial the (n+1)th phone number for the first connection
and to dial the (n+2)th phone number for the second connection.
Use ATDSn+Sm, (n=0-39; m=0-39), to dial the (n+1)th phone number for the first
connection and the (m+1)th phone number for the second connection.

Dynamic Bandwidth Allocation

When dynamic bandwidth allocation (DBA) is enabled (by default), you can place or
answer a voice call (and only one) from a device that is attached to one of the a/b
adapters while a CCB call is active. The Omni TA128 automatically removes one of the
CCB connections and uses it for the voice call. Once the voice call ends, the Omni
TA128 automatically reestablishes that channel for CCB operation. The dynamic
bandwidth allocation function can only be effective when the Omni TA128 is in the
calling site (the client site). The following command can be used to select the DBA
function.
ATCE0
ATCE1
The availability of DBA for the various bundle protocols is outlined below:
Enable Channel-
Bundling
Applicable Data
Protocols
Dynamic Bandwidth
Allocation
(Disable the DBA function)
(Enable the DBA function) Default
Multiple Link
Protocol (MLP)
AT&J3
X.75 (ATB0n), V.120
(ATB20)
No
'cFos' Channel
Bundling (CCB)
AT&J3
X.75 (ATB0n), V.120
(ATB20)
Yes
(ATCE1)
8-3
Multilink PPP
AT&J3
PPP (ATB40)
Yes
(ATCE1)