copl if this should be necessary the user data treated in this way are then output via the physical interface toward the platform copl given a basic switching granularity of a peripheral device of 120 u00d7 64 kbit s it is therefore possible to attain a net payload data rate of 6 7 mbit s load 0 8 erl per bearer channel on a physical interface to the copl e g 1 u00d7 ethernet 100baset or 4 u00d7 e1 an expansion module of the peripheral device pe term can preferably be used to provide the physical interface and for protocol conversion the devices pe prh and pe term can be used exclusively for the described functionality they can however also provide further switching functions for the network system in the context of the limits of its resources in particular they can coincide with peripheral devices whose hardware serves to provide virtual peripheral devices the functionality of said virtual peripheral devices is described in detail in european patent application ep 99123208 3 for fail safety reasons the peripheral devices pe prh pe term can be designed as duplicated peripheral device as is shown by way of example in fig6 likewise the physical interface between the peripheral device pe term and the platform copl is usually designed to be at least duplicated finally the platform copl itself is designed with internal redundancy as a device of a switching center with partially centralized functions at the present time platforms copl with microsynchronous parallel operation 1 duplicated interface and platforms with a cluster configuration at least 2 duplicated interfaces are customary as are illustrated in fig3 and 4 if.