Known Behavior
33
Release 11.0.1
SSH
If the SRP module restarts when SSH is configured in a VR other than default,
SSH can sometimes become disabled. This happens if SSH attempts to bind
with a VR before the VR comes back up after the restart. In this event, a
warning message is generated to alert you to the fact that SSH is disabled in
that VR. You must manually re-enable SSH either by accessing the console VTY
or creating a Telnet session to the router.
Stateful SRP Switchover (High Availability)
Additional processing is required to maintain and mirror the necessary state
information that enables subscriber sessions to stay up across an SRP failover.
As a result, the performance of other control plane functions is reduced.
Specifically, call setup rates are lower than in previous releases.
We have ongoing development activities to characterize and improve call setup
rates in future releases.
Stateful SRP switchover remains inactive for 20 minutes after an initial
cold-start or cold-restart of the router. This delay enables the system to reach a
stable configuration before starting stateful SRP switchover.
If you want to override the 20-minute timer, turn high availability off by using
the
mode file-system-synchronization
command, and then on again by using
the
mode high-availability
command.
When IP tunnels are configured on a router enabled for stateful SRP switchover,
and the Service Module (SM) carrying these tunnels is reloaded, stateful SRP
switchover transitions to the pending state. Stateful SRP switchover remains in
the pending state for 10 minutes following the successful reloading of the SM.
This amount of time allows for IP tunnel relocation and for the tunnels to
become operational again on the SM. If an SRP switchover occurs while in the
pending state, the router performs a cold restart.
Work-around:
None.
After a stateful SRP switchover, each layer of the interface columns must
reconstruct its interfaces from the mirrored information. While the interfaces
are being reconstructed the SRP module cannot send or receive frames,
including the protocol frames that signal graceful restart behavior with OSPF
and IS-IS peers. If the configured hold time is too short, peers might mistakenly
declare the adjacency down during the time in which the graceful restart is
taking place. [Defect ID 65132]
NOTE:
Rapid call setup rates are most important following an outage that causes
all subscribers to drop, because many of the dropped subscribers will immediately
attempt to reconnect. This type of outage occurs far less frequently with stateful
SRP switchover.
