Table 31-1 on page 873 illustrates the content of a LID-routed SMP's data payload. After LIDs have been assigned to all ports on CAs and routers and to port 0 on each switch, the port that originates an SMP packet specifies:
the LID of the destination port in the packet's DLID field and
its own LID in the packet's SLID field (in case a response is required).
Switches then forward the packet from source to destination by consulting their forwarding tables (which the Master SM set up after it had completed discovery).
This is referred to as a LID-routed SMP.
Dword | Byte 0 | Byte 1 | Byte 2 | Byte 3 | ||
---|---|---|---|---|---|---|
0 | Base MAD Header | Base Version = 01h | Management Class = Subn | Class Version = 01h | R | SM Method (see Table 27-1 on page 774) |
1 | Status is only meaningful in response packets. See Table 27-2 on page 776. | Not used | ||||
2 | Transaction ID | |||||
3 | ||||||
4 | SM AttributeID | Reserved | ||||
5 | AttributeModifier | |||||
6 | SMP- specific fields | M_Key | ||||
7 | ||||||
8–15 | 32 bytes Reserved | |||||
16–31 | 64 bytes of SMP Data—Attribute content on a SubnGetResp() or a SubnTrap(Notice) | |||||
32–63 | 64 bytes Reserved |