Enterasys csx400 Betriebsanweisung
Local Management
1-4
Local Management User’s Guide
The following are reasons to use ISDN call backup:
•
Hardware failure of a nailed-up PPP connection
•
line failure
Use call backup if either of the following conditions exist when using Frame Relay:
•
DLCI circuit fails to connect in a predetermined amount of time.
•
DLCI goes inactive.
The following is one circumstance in which it might not be advisable to use call backup:
•
When going point-to-multipoint, setting backup on the head-end side is not recommended. If
any DLCI fails, the backup would be activated. This may be cost prohibitive.
any DLCI fails, the backup would be activated. This may be cost prohibitive.
Call Backup Topology
In Call Backup topology, two channels are connected, but one of them is a Switched Virtual
Circuit (SVC) that is only activated upon failure of the primary channel. The primary channel is a
Permanent Virtual Circuit (PVC) running Frame Relay or PPP. The Backup channel is either
ISDN BRI or PPP.
Circuit (SVC) that is only activated upon failure of the primary channel. The primary channel is a
Permanent Virtual Circuit (PVC) running Frame Relay or PPP. The Backup channel is either
ISDN BRI or PPP.
shows the supported configurations at the initial release of the call backup feature.
gives details on a backup configuration using modems.
Table 1-1 Call Backup Configurations
Primary Interface
Backup Interface
Support
PPP (WPIM-T1, WPIM-E1,
WPIM-DDS, and WPIM-SY)
WPIM-DDS, and WPIM-SY)
ISDN BRI (WPIM-S/T)
YES
PPP (WPIM-T1, WPIM-E1,
WPIM-DDS, and WPIM-SY)
WPIM-DDS, and WPIM-SY)
PPP (WPIM-SY to Sync
Modem)
Modem)
YES
Frame Relay (WPIM-T1, WPIM-E1,
WPIM-DDS, and WPIM-SY)
WPIM-DDS, and WPIM-SY)
ISDN BRI (WPIM-S/T)
YES
Frame Relay (WPIM-T1, WPIM-E1,
WPIM-DDS, and WPIM-SY)
WPIM-DDS, and WPIM-SY)
PPP (WPIM-SY to Sync
Modem)
Modem)
YES