Suppose two out of four trunks are connected to one switch and
the other two to another switch.
Now SS7 signalling fail-over is arranged via two switches and two
Signalling Transfer Points (STPs) over 2 link sets, as can be seen
from the schematic and the SS7 window below. Since the trunks
are terminated by the switches, the DPCs of trunk 1 and 2 are 100
and 101, respectively.
However, both links are terminated by the STPs. Link set 1
contains SS7 trunk 1 and is terminated by an STP with DCP 200.
Link set 2 contains SS7 trunk 3 and is terminated by an STP with
DCP 201.
For each link two routes are available to two switches, one directly
and one via an STP. Priority 1 is assigned to all direct links,
whereas all links via STPs have the lower priority 2.

SS7 Configuration – Example 2