Cabletron Systems 1800 Frame Relay Backup

7-2 Smart Switch 1800 4. 0 User Guide , Rev 0 1
Frame Relay Backup
Frame relay virtual-circuit backup in the SmartSwitch 1800 provides frame relay
DLCIs with automatic backup protection in the event of LMI loss or port failure. (A
DLCI is considered down/inactive if level 1 is down. If LMI is used, the DLCI is also
considered inactive if not reported as active in a Full Status Message from the DCE.)
A physic al frame relay po rt can be de dicat ed to pr ov iding ba ckup D L CIs, or ba ckup s
can co-exist with "regular" DLCIs on a port.
In a backup configuration, one end is considered the "initiating" node and the other the
"remote" node. The initiating en d is the one that will es tablish the backup lin k if it dis-
covers that the primary link is down. (A node can be the initiating node for some
backup configurations and the remote node for others.)
Any sessions in progress when a primary DLCI goes down will not be
transferred directly to t he backup DLCI, but will be reset, then established
on the backup.
DLCIs used for backup on the initiating node are assigned to "backup groups," each
of which can contain up to ten backup DLCIs . A backup group i s then assigned t o one
or more "primary" DLCIs (the ones that will be backed up).
The basic procedure for configuring backup DLCIs is:
1. Configure all DLCIs that will be backed up or used as backups. All parameters
can be configured for each DLCI except specifying a Backup Group Number on a
primary DLCI (that will be backed up) on an "initiating" node (which will initiate
the switchover to a backup DLCI) .
2. Configure backup groups. A backup group is one or more DLCIs that will act as
backup if the pr i mary goe s down .
3. Conf igure B ackup Group Numbers and related information for primary DLCIs.
This will assign a Backup Group to each primary DLCI.
For each example in Figu re 7- 1, assume that Node 1 is a remote site and Node 2 is a
central site. Also assume that Node 1 will be the initiating node. On that node, the
primar y D LCI is on port 2 a nd the bac kup is on port 0.