InfiniBand Network Architecture

Why Assign a LID Range to a Port?

DLID Defines Path Taken by Packet

As shown in the previous example, a switch uses the packet's DLID field to access its Forwarding Table and select which port to output the packet through.

Different DLID Can Result in Alternate Path to Target Port

As mentioned earlier, the SM may optionally assign a range of LID addresses to a port. Assume that the target port used in the previous example has had a LID range assigned to it. During configuration, the SM builds the Forwarding Table within each switch. In this case, it can program a different output port for each of the LIDs belonging to the same destination port, thereby setting up alternate paths to the same physical destination port. By selecting a particular ...