8-66
Cisco ONS 15454 DWDM Reference Manual, R8.5
78-18343-02
Chapter 8      Transponder and Muxponder Cards
8.11.8    Layer 2 Over DWDM Protection
A FAPS switchover happens in the following failure scenarios:
 • DWDM line failures caused by a fiber cut
 • Unidirectional failure in the DWDM network caused by a fiber cut
 • Fiber pull on the master card trunk port followed by a hard reset on the master card
 • Hard reset on the master card
 • Hard reset on the slave card
 • An OTN failure is detected (LOS, OTUK-LOF, OTUK-LOM, or OTUK-LOM on the DWDM 
receiver port in the case of ITU-T G.709 mode)
 • Trunk ports are moved to OOS,DSBLD (Locked,disabled) state
 • Improper removal of XFPs
A FAPS switchover does not happen in the following scenarios:
 • Slave card trunk port in OOS,DSBLD (Locked,disabled) state followed by a hard reset of the slave 
card
 • OTN alarms raised on the slave card trunk port followed by a hard reset of the slave card
 • Dual failure in the VLAN ring caused by fiber pull on the master and slave cards and restoration of 
a single failure
 • Dual failure in the VLAN ring caused by the trunk port of master and slave cards in OOS,DSBLD 
(Locked,disabled) state and restoration of a single failure by placing one trunk port in IS state
 • Dual failure in the VLAN ring due to the trunk port of master and slave cards in OOS,DSBLD 
(Locked,disabled) state followed by a hard or soft reset of the master card