Scope

Problem Statement

Multi-Rail (MR) and Health add the capability of using all the interfaces available. Instead of configuring each interface on a separate LNet, it is now possible to configure multiple interfaces on the same LNet. MR code can now iterate over all interfaces and select an interface to send a message based on one of the following criteria:

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However, there is no way for the user to override this selection criteria. This becomes particularly useful when desiring to redirect traffic over specific paths depending on source and/or destination NIDs

Use Cases

There are two uses cases outlined on

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1. Assigning priority to different networks. For example if you have an OPA and a IB network and you want to always use the IB network as long as it's alive.
2. Preferring a specific path to avoid a bottleneck in the fabric

Work Overview

There are four primary tasks in this project

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The High Level Design document will detail each of these tasks.

Requirements

These requirements are from the original MR Requirements document.

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