The SM is the software entity that performs the following functions:
Discovers the topology of the subnet that it manages.
Assigns a common Subnet ID (aka Subnet Prefix) to all of the ports in its subnet.
Assigns an address to each port in its subnet (an address that is unique within that subnet). This address is referred to as a port's Local ID, or LID.
Establishes the possible paths between all endnodes in the subnet.
Sweeps (i.e., scans) its subnet on a regular basis looking for topology changes (devices added or removed, changes in the operational state of links, etc.).
The SM may reside within or behind any device in the subnet, but most typically would consist of a program running on a ...