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Cisco MDS 9000 Family NX-OS Interfaces Configuration Guide
OL-29284-01, Release 6.x
Chapter 3 Configuring Fibre Channel Interfaces
Guidelines and Limitations
Note When a Cisco or another vendor switch port is connected to a Generation 1 module port (ISL
connection), the receive buffer-to-buffer credits of the port connected to the Generation 1 module port
must not exceed 255.
Local Switching Limitations
• All ports in the module must be in shared mode. Use the switchport ratemode shared command to
ensure that all the ports in the module are in shared mode.
• No E ports are allowed in the module because E ports must be in dedicated 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.
You can use the show port index-allocation command to display the allocation of port indexes on the
switch.
switch# show port index-allocation
Module index distribution:
------------------------------------------------------+
Slot| Allowed | Allotted indices info |
| range | Total | Index values |
----|---------|-------|------------------------------|
1 | ----- | - | (None) |
2 | ----- | - | (None) |
3 | ----- | - | (None) |
4 | ----- | - | (None) |
5 | 0-1023| 32 | 0-31 |
6 | ----- | - | (None) |
9 | ----- | - | (None) |
10 | ----- | - | (None) |
11 | ----- | - | (None) |
12 | ----- | - | (None) |
13 | 0-1023| 48 | 32-79 |
SUP | 253-255 | 3 | 253-255 |
