Placing Units On Top of Each Other 23The Power-up Sequence 24Connecting a Redundant Power System 24Powering-up the Switch 610 24Checking for Correct Operation 24Choosing the Correct Cables 25Solving Problems Indicated by LEDs 25Managing the Switch 26A S AFETY I NFORMATIONImportant Safety Information 28L’information de Sécurité Importante 30Wichtige Sicherheits-informationen 32B P IN- OUTSNull Modem Cable 33PC-AT Serial Cable 33Modem Cable 34RJ-45 Pin Assignments 34C TECHNICAL SPECIFICATIONSD TECHNICAL SUPPORTOnline Technical Services 37World Wide Web Site 373Com Knowledgebase Web Services 373Com FTP Site 383Com Bulletin Board Service 383Com Facts Automated Fax Service 39Support from Your Network Supplier 39Support from 3Com 39Returning Products for Repair 41