access or peripheral shelves 170 two such shelves 170 being shown each peripheral shelf 170 features of a plurality of universal card slots ucs for housing user equipment interface cards 174 which cards include input output ports 114 the interface cards 174 include cards such as system cards which terminate or originate atm connections and cell relay cards the cell relay cards may take incoming atm cells translate their vpi vci values and transport the cells to the switching core 164 so that the cells can be routed to another cell relay card e g an egress card which in turn transmits the cells to the next network element in the message path the peripheral shelf 170 also includes a control card 176 one or more service cards 178 and hub card 180 the hub card 180 multiplexes a plurality of 200 mb s u201c add u201d buses 182 from the various interface cards found on a particular peripheral shelf 170 onto a high speed 800 mb s intershelf link isl bus 184 connecting the shelf 170 with the switching core 164 this is accomplished at multiplexer 183 of the hub card 180 the hub card 180 also terminates the isl bus 184 from the switching core 164 and drives a multi drop bus 186 connected to each interface card 174 on shelf 170.