SMP MADs

General

A detailed description of SM methods, attributes, and modifiers can be found in “SM Methods and Attributes” on page 809. Additional information on the SM can be found in the following chapters:

• “Multiple SMs” on page 851.

• “Discovery” on page 871.

LID-Routed SMPs

Once the Master SM has assigned LID addresses to all ports in the subnet, SMP's may be transmitted in the same manner as any normal packet: switch Forwarding Tables use the packet's LRH:DLID to guide the packet to the destination port. In that case, the 256-byte MAD encapsulated in the SMP's data payload field has the format shown in Table 28-5 on page 788.

Directed-Route SMPs

In some situations, the SM must transmit a request MAD to a destination device when the path to the destination port has not yet been fully configured. Only some, or none, of the switches in the path have valid Forwarding Tables, and the destination port may or may not have had a LID address assigned to it yet.

In this case, the MAD encapsulated in the SMP's data payload field has the format shown in Table 28-6 on page 789 and is referred to as a directed-route SMP.

A detailed description of directed-route SMP usage can be found in “Discovery” on page 871.