In SCAT-40 and higher the method of vertical scaling ¹⁾ is used named as a multicluster. In fact a 2-clusters it's like 2 dpi servers in one process. Each has its own set of ports, workflows, etc. but there are general data. A result symmetric traffic is not required as in the case of horizontal scaling. If you look at the hardware configuration of the server SCAT-40 is like two SCAT-20, but with one CPU, and SCAT-80 is four SCAT-20.

When configuring a multicluster, you need to specify the distribution of network interfaces over clusters:

in_dev = dna0 | dna2
out_dev = dna1 | dna3

here,
the sign | separates pairs of interfaces related to different clusters
dna0 ↔ dna1 is the pair of the first cluster
dna2 ↔ dna3 is the pair of the second cluster