Air filters

Flexible PIC Concentrators (FPCs)

Front and rear fan trays

Physical Interface Cards (PICs)

Power supplies

Backup SONET Clock Generators (SCGs)

Switch Interface Boards (SIBs)

Master T-CB (if nonstop active routing is configured)

Backup T-CB

Backup Routing Engine

Connector Interface Panel (CIP)

Nonredundant T-CB

Master T-CB (if nonstop active routing is not configured)

Nonredundant Routing Engine

Master Routing Engine (if nonstop active routing is not configured)

Master and nonredundant SCGs