CISCO used Catalyst GigaStack GBIC WS-X3500-XL
– Half-duplex stacking using only one GBIC slot for each switch
– Full-duplex connectivity between two switches
– Support for redundant loop configurations in a GigaStack GBIC stack
– Support for IOS Release 12.0(5)XU or later for Catalyst 2900 XL and 3500 XL switches, support for Release 12.1(6)EA2 or later for Catalyst 2950 switches, and support for Release 12.1(4)EA1 or later for Catalyst 3550 multilayer switches
– Management through the Cisco IOS command-line interface (CLI) or the web-based Cluster Management Suite (CMS)
– Field-replaceable
