Configuring Virtual Circuits 139
Figure 109 Completed Data Port VCC Virtual Circuit
9 Press any key to return to the Virtual Circuit menu.
Configuring CBR Circuits for DBA
This section provides guidelines for configuring CBR circuits for various types of
dynamic bandwidth allocation (DBA)—both for CAS (channel associated signaling)
and CCS (common channel signaling applications). Table 25 summarizes the key
CBR port and virtual circuit parameters for these types of applications. For details
about how DBA works, see “DS0 Signaling and Dynamic Bandwidth Allocation” in
Appendix B.
Checking the Data Bytes to Determine a DBA Bits Mask Setting CCS
monitors for voice activity. In most cases the default DBA Bits Mask (127) works,
but if you are having a problem with a CCS circuit, you can set the DBA Bits Mask
to monitor any bits. The unit will monitor the virtual circuit, and you can use the
activity reported on the channel (reported under CBR ATM statistics as Data Bytes
To) to determine the proper DBA Bits Mask. For details about checking the data
bytes, see “CBR ATM Statistics” in Chapter 5.
Table 25 CBR Port and Circuit Settings for CAS versus CCS
Parameter Setting for CAS Setting for CCS
Port Mode Structured Voice Structured Data
Port Data Bits Mask N/A Leave at default setting (127) in
most cases; for details see
“Checking the Data Bytes to
Determine a DBA Bits Mask
Setting” after this table
VC Payload Size/Type Voice Set automatically when VC
Mode set to DBA
VC Onhook Detection Enabled Set automatically when VC
Mode set to DBA
VC Mode N/A DBA for channels 1-23 (DSX-1)
or 1-15 and 17-31 (E1)
Normal for channel 24 (DSX-1)
or 16 (E1)
