> # All ports in the module must be in shared mode. Port Index Limitations

> Cisco MDS 9000 switches allocate index identifiers for the ports on the modules. These port indexes cannot be configured. You can combine Generation 1, Generation 2, Generation 3, and Generation 4 switching modules, with either Supervisor-1 modules or Supervisor-2 modules. However, combining switching modules and supervisor modules has the following port index limitations:

> - Supervisor-1 modules only support a maximum of 252 port indexes, regardless of the type of switching modules.
> - Supervisor-2 modules support a maximum of 1020 port indexes when all switching modules in the chassis are Generation 2 or Generation 3.
> - Supervisor-2 modules only support a maximum of 252 port indexes when only Generation 1 switching modules, or a combination of Generation 1, Generation 2, Generation 3, or Generation 4 switching modules are installed in the chassis.

> Note On a switch with the maximum limit of 252 as port index, any new module that exceeds the limit does not power up when installed.

> Generation 1 switching modules have specific numbering requirements. If these requirements are not met, the module does not power up. The port index numbering requirements include the following:

> - If port indexes in the range of 256 to 1020 are assigned to operational ports, Generation 1 switching modules do not power up.
> - A block of contiguous port indexes is available. If this block of port indexes is not available, Generation 1 modules do not power up. Table 13-10 shows the port index requirements for the Generation 1 modules.

> Note If the switch has Supervisor-1 modules, the block of 32 contiguous port indexes must begin on the slot boundary. The slot boundary for slot 1 is 0, for slot 2 is 32, and so on. For Supervisor-2 modules, the contiguous block can start anywhere.

> Table 13-10 Port Index Requirements for Generation 1 Modules
> Generation 1 Module | Number of Port Indexes Required
> --- | ---
> Supervisor-1 Module | Supervisor-2 Module
> 16-port 2-Gbps Fibre Channel module | 16 | 16
> 32-port 2-Gbps Fibre Channel module | 32 | 32
> 8-port Gigabit Ethernet IP Storage Services module | 32 | 32
> 4-port Gigabit Ethernet IP Storage Services module | 32 | 16
> 32-port 2-Gbps Fibre Channel Storage Services Module (SSM). | 32 | 32
> 14-port Fibre Channel/2-port Gigabit Ethernet Multiprotocol Services (MPS-14/2) module | 32 | 22

> The allowed mix of Generation 1 and Generation 2 switching modules in a chassis is determined at run-time, either when booting up the switch or when installing the modules. In some cases, the sequence in which switching modules are inserted into the chassis determines if one or more modules is powered up.

> When a module does not power up because of a resource limitation, you can see the reason by viewing the module information in the Information pane.

> For information on recovering a module powered-down because port indexes are not available, refer to the Cisco MDS 9000 Family Troubleshooting Guide.

> Tip Whenever using mixed Generation 1 and Generation 2 modules, power up the Generation 1 modules first. During a reboot of the entire switch, the Generation 1 modules power up first (default behavior).

> Copyright 2010-2015, Cisco Systems, Inc. All rights reserved.