data links 28 and the ip network 52 are used to support connections for carrying tcp ip traffic between the units 14 for example a first connection 54 a may be established between the data storage systems 14 a and 14 b a second connection 54 b may be established between the data storage systems 14 b and 14 c a third connection 54 c may be established between the data storage systems 14 c and 14 a in the system 50 the data storage systems 14 are configured for remote data mirroring capability more specifically in the example shown there are eight device groups s 1 s 2 s 3 s 4 t 1 t 2 t 3 t 4 which are indicated by reference numerals 56 a 56 b 56 c 56 d 56 e 56 f 56 g 56 h respectively four of the device groups s 1 through s 4 are source device groups and device groups t 1 through t 4 are target device groups in the example shown the data storage systems 14 are configured in the following manner the data storage system 14 a supports device groups s 1 s 2 and t 3 the data storage system 14 b supports.