ZyXEL Communications XS3800-28 Cli Reference Manual page 214

In this example, we enable MRSTP on ports 21-24. Port 24 is connected to the host while ports 21-23 are
connected to another switch.
sysname(config)# configure
sysname(config)# spanning-tree mode MRSTP
sysname(config)# mrstp 1
sysname(config)# mrstp interface 21-24
sysname(config)# no mrstp interface 21-23 edge-port
Chapter 56 MRSTP Commands
Ethernet Switch CLI Reference Guide
214