GMPs Can Transit Routers

The SM is only permitted to manage the devices in its own subnet. For this reason, SMPs never contain a GRH (only an LRH), and they are never permitted to cross a router into another subnet.

As mentioned at the beginning of this chapter, a GSM may only have responsibility for managing the devices in a single subnet, or may have responsibility for managing the devices residing in multiple subnets. The scope of its management operations is GSM implementation-specific.

If a GSM does manage devices in multiple subnets, it can generate GMPs with a GRH as well as an LRH.