Optical Network System (ONS) 15454 System Software Version 2.2.x
Also applies to earlier versions.
This notice applies when pass-thru nodes on Bidirectional Line Switch Ring (BLSR) rings have circuits that do not use the same Synchronous Transport Signal (STS) or Virtual Tributary (VT) entering the node as exiting. During forced switches (both East and West spans), fiber pulls (both East and West cards), or power down of the node, traffic loss can result for these circuits as BLSR protection will not protect these circuits.
This issue and solution were identified and verified in the lab.
Traffic on circuits on BLSR Rings that do not utilize the same STS or VT entering and exiting a pass-thru node is lost when forced switches on both the East and West spans, fiber pulls on both East and West cards, or power down of the pass-thru node is performed.
With Release 3.0, the ONS 15454 will restrict pass through cross connects to using the same STS or VT path throughout the ring, whether this is manually or automatically routed.
Creating BLSR Protected Circuits in Cisco Transport Controller (CTC) version 2.2.2 (or earlier) If you have circuits that are traversing different STS or VT paths in your network, you need to delete and recreate these circuits using the Circuit Creation Procedure documented in the ONS 15454 User Documentation (online), or section 4.6 in the printed manual. You need to deselect "Route Automatically" from the circuit creation pane to provision the circuit paths manually.
Creating BLSR Protected Circuits in CTC version 3.0.0 (or later) If you have circuits that are traversing different STS or VT paths in your network, you need to delete and recreate these circuits using either the manual circuit creation procedure or the automatic circuit creation procedure.
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