Alcatel-Lucent 7710 SR SONET, Configuration Manual

Page: 64 / 496

Ports
Page 64 7710 SR OS Interface Configuration Guide
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If the remote end indicates an APS switch and the router can RX and TX on the circuit
newly selected by the remote end, then the router will move its TX direction and will
perform an APS switch of its RX direction (unless the router already TX and RX on
the newly selected circuit).

If the remote end indicates an APS switch and the router cannot RX and TX on the
circuit newly selected by the remote end (for example due to a higher priority local
request, like a force request or manual request, etc.), then L-AIS are sent on the circuit
newly selected by the remote end to force it back to the previously active circuit.

The sent L-AIS in the above cases can be either momentary 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. SR-OS provides debugging information
that informs operators about the APS-induced L-AIS.
Unidirectional 1+1 Signalling and Datapath APS
Uni 1+1 Sig+Data APSsupports unidirectional switching operations, 1+1 signaling and 1+1 data
path.
In the ingress direction (Rx) switching is done based on local requests only as per the APS
specifications. K-bytes are used to signal the far end the APS actions taken.
In the egress direction (Tx), the data is transmitted on both active and protecting circuits.
Each end of the aps group may be actively listening on a different circuit.
The APS channel (bytes K1 and K2 in the SONET header) is used to exchange APS protocol
messages.
In Uni 1+1 Sig+Data APS a received L-RDI signal on the active circuit does not cause that circuit
(port) to be placed out of service. The APS group can continue to use that circuit as the active
receiver. This behavior is not configurable.
Uni 1+1 Sig+Data APS also supports configurable:
• Debounce timers for signal failure and degradation conditions
• Suppression of L-RDI alarm generation