HP 600 Series, Services And Applications

Page: 216 / 316

router will not accept the call (based on configured call restrictions), it
immediately drops DTR. Otherwise the adapter subsequently drops CTS. As
soon as the switched circuit is complete, DSR (data set ready) is raised by
each adapter and the circuit is established.
Any of the synchronous interfaces except X.21 (that is, RS-232/V.24/V.28,
V.35, RS-449/422/V.36) may be used to connect to a V.25 bis adapter. The X.21
interface lacks the necessary hardware-control signals required to imple-
ment V.25 bis.
Connections may be initiated in one of two ways with a V.25 bis adapter:
When data is available or on incoming call
When the circuit is enabled
Table 4. Valid Connection Initiation Parameters for V.25 bis
Circuit Group Members and Backup Members
Side A Router Side B Router
Circuit is enabled Circuit is enabled
Circuit is enabled Data is available or on incoming call
Data is available or on incoming call Circuit is enabled
Data is available or on incoming call Data is available or on incoming call
The valid combinations of connection initiation parameters for circuit group
members and circuit group backup members using V.25 bis adapters are
shown in the shaded fields of table 4. Pool circuit group members can
only
be configured to connect when “data is available or on incoming call”.
As in the case of manual adapters, when the connection initiation
paramenter is set to “circuit is enabled” on both sides, the circuit will never
hang up. The user will incur charges for a permanently open circuit!
Connection Controls—V.25 bis Adapter
V.25 bis circuits provide the same connection controls as described
previously in the section “Connection Controls—Manual Adapter”. In
addition, call restrictions may be configured with V.25 bis circuits. This
involves specifying a list of originating phone numbers for which incoming
calls will be accepted. Note that these call restrictions only work on ISDN
networks with automatic number identification (ANI).
Improving Network Availability
Switched Circuit Types
3-22