InfiniBand Network Architecture

Port Numbering

The following rules govern the number of (and the numbering of) ports that may be implemented on CAs, switches, and routers:

• CA:

  - As few as one or as many as 255 ports can be implemented on a CA.

  - They are numbered starting at one.

  - Each CA port must be assigned at least one 16-bit LID address by the SM at startup time. Each port must have a LID address that is unique within the subnet. The SM may optionally assign a range of LID addresses to a CA port. For more information, see “Why Assign a LID Range to a Port?” on page 137.

• Router:

  - A router may implement as few as two or as many as 255 ports. Although the specification doesn't say the lower limit is two ports, a router with one port would be a deadend. Consider that a router's ...