InfiniBand Network Architecture

Assignment of Port's Subnet ID and GUID(s)

Introduction

Refer to Figure 8-3 on page 147. The upper 64 bits of a port's assigned GID is its assigned Subnet ID, while the lower 64 bits is the port's assigned GUID. The next two sections describe how these two values are assigned to the port.

Port's Subnet ID Assignment

General

During configuration, the SM assigns the same Subnet ID (sometimes referred to as the GID Prefix or Subnet Prefix) to every port within the subnet that it manages. It is stored in each port's PortInfo.GidPrefix attribute element.

Default Subnet ID

The IBA specification doesn't say what default value the PortInfo.GidPrefix attribute contains immediately after power-up prior to Subnet ID assignment by the SM. It's the author's ...