InfiniBand Network Architecture

Packet Routing During Discovery

Problem

Before all ports have been assigned LID addresses and switch Forwarding Tables have been initialized by the Master SM, the SM must use a different method to direct a packet to its destination. It uses a directed-route SMP. There are two basic scenarios:

1. Scenario: The SM must be able to deliver a MAD containing an attribute access request to a CA or router port or to a switch's port 0 without knowing its LID address.

2. Scenario: While the SM may know the destination port's LID address, the switches along the route may not have all been configured with LID addresses and Forwarding Tables.

Four Possible Scenarios

There are four possible scenarios:

1. The entire path to the target port is unaddressable:

   - A LID ...