This is the second edition of the Multilayer Switching Companion Guide for students of the CCNP 3 Multilayer Switching Cisco Networking Academy Program course. The book is specifically designed to supplement the CCNP 3 Version 3.0 online course to prepare students for the current BCMSN exam. Since the first edition of the book, Cisco has moved toward an IOS-only Catalyst solution. All new Catalyst devices now ship with built-in IOS functionality. There is also a dramatic set of additions to the previous BCMSN material and the previous edition of the Multilayer Switching Companion Guide: inter-VLAN routing using routed ports and switch virtual interfaces (SVIs); new Spanning Tree Protocols such as RSTP and MST; redundancy with VRRP, GLBP, SRM, and SLB; Architecture for Voice, Video, and Integrated Data (AVVID); the range of Quality of Service technologies for campus LANs; Catalyst switch security, including port security, VSPAN, RSPAN, VLAN ACLs, and Private VLANs; and Metro Optical networking with Transparent LAN Services. This portable desk reference includes this wide array of new technologies, providing both background theory and detailed IOS configuration procedures. The accompanying CD-ROM includes alternative Catalyst 4006 and 2900XL labs for Academies using the original CCNP bundle, e-Labs to parallel the labs appearing in the Multilayer Switching Lab Companion, and a test engine with numerous exam questions to help students prepare for the BCMSN exam.