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Cisco FlexStack stacking with a hot-swappable module and IOS software provides true stacking, all switches in a stack act as a single switch unit. The Cisco FlexStack provides a unified data plane, unified configuration, and single IP address management for a group of switches. The advantages of true stacking are lower total cost of ownership through simplified management and higher availability. Cisco FlexStack supports cross-stack features including Etherchannel, SPAN and FlexLink technology. A stack module can be added to any Catalyst 2960-S switch with LAN Base software to quickly upgrade the switch to make it stack capable, and the switch added to the stack will upgrade to the correct Cisco IOS® Software version and transparently become a stack member. Figure 3 shows the FlexStack stacking module for the Catalyst 2960-S.