Revertive Mode; Mirroring Support - Alcatel-Lucent 7750 SR OS Interface Configuration Manual

Port Features

Revertive Mode

The APS 1+1 system also provides the revertive and non-revertive modes where non-revertive
switching is the default option. The user can configure the switch of activity between the working
and protection lines to be either revertive or non-revertive. In revertive switching, the activity is
switched back to the working port after the working line has recovered from a failure (or the
manual switch is cleared). In non-revertive switching, a switch to the protection line is maintained
even after the working line has recovered from a failure (or if the manual switch is cleared).
A revert-time is defined for revertive switching so frequent automatic switches as a result of
intermittent failures are prevented. The revert-time is a user-provisioned entity with a period of 0
to 60 minutes in 1-minute increments. A change in this value takes effect upon the next initiation
of the wait to restore (WTR) timer. It does not modify the length of a WTR timer that has already
been started. The WTR timer of a non-revertive switch can be assumed to be infinite.
In case of failure on both working and the protection line, the line that has less severe errors on the
line will be active at any point in time. If there is signal degrade on both ports, the active port that
failed last will stay active. When there is signal failure on both ports, the working port will always
be active. The reason is that the signal failure on the protection line is of a higher priority than on
the working line.

Mirroring Support

Mirroring parameters configured on a specific port or service, are maintained during an APS
failover.
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→ The L-AIS sent by the 7750 SR in the above cases can be either momentary (sent for
approximately 100 ms) or persistent. The persistent L-AIS is sent under the following
conditions:
−
On the protection circuit when the protection circuit is inactive and cannot be
selected due to local SF or Lockout Request.
−
On the working circuit as long as the working circuit remains inactive due to a
local condition. The persistent L-AIS is sent to prevent revertive switching at the
other end.
In all other cases a momentary L-AIS is sent. The 7750 SR provides debugging
information that informs operators about the APS-induced L-AIS.
7750 SR OS Interface Configuration Guide