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Assigning buffer-to-buffer credits to F-Ports in the same port group as the ISL

You must assign the buffer-to-buffer credits to the F-ports if they are in the same port group as the ISL. If the ports do not have the required buffer-to-buffer credits, the ISL could be inoperative. This task is not required if the F-ports are not in the same port group as the ISL port.

If the F-Ports are in a port group that contains the ISL, this task must be performed on each FC switch in the MetroCluster configuration.

  1. Issue the following command to enter configuration mode: config t
  2. Enter the following command to set the interface configuration mode for the port: interface port-ID
  3. Disable the port:shut
  4. If the port is not already in F mode, set the port to F mode by entering the following command: switchport mode F
  5. Set the buffer-to-buffer credit of the non-E ports to 1 by using the following command: switchport fcrxbbcredit 1
  6. Re-enable the port:no shut
  7. Exit configuration mode:exit
  8. Copy the updated configuration to the startup configuration:copy running-config startup-config
  9. Verify the buffer-to-buffer credit assigned to a port by entering the following commands: show port-resources module 1
  10. Issue the following command to exit configuration mode: exit
  11. Repeat these steps on the other switch in the fabric.
  12. Verify the settings:show port-resource module 1

In this example, port fc1/40 is the ISL. Ports fc1/37, fc1/38 and fc1/39 are in the same port group and must be configured.

The following commands show the port range being configured for fc1/37 through fc1/39:
FC_switch_A_1# conf t
FC_switch_A_1(config)# interface fc1/37-39
FC_switch_A_1(config-if)# shut
FC_switch_A_1(config-if)# switchport mode F
FC_switch_A_1(config-if)# switchport fcrxbbcredit 1
FC_switch_A_1(config-if)# no shut
FC_switch_A_1(config-if)# exit
FC_switch_A_1# copy running-config startup-config

FC_switch_B_1# conf t
FC_switch_B_1(config)# interface fc1/37-39
FC_switch_B_1(config-if)# shut
FC_switch_B_1(config-if)# switchport mode F
FC_switch_B_1(config-if)# switchport fcrxbbcredit 1
FC_switch_A_1(config-if)# no shut
FC_switch_A_1(config-if)# exit
FC_switch_B_1# copy running-config startup-config

The following commands and system output show that the settings are properly applied:

FC_switch_A_1# show port-resource module 1
...
Port-Group 11
 Available dedicated buffers are 93
       
--------------------------------------------------------------------
Interfaces in the Port-Group       B2B Credit  Bandwidth  Rate Mode  
                                      Buffers     (Gbps)
       
--------------------------------------------------------------------
fc1/37                                     32        8.0  dedicated
fc1/38                                      1        8.0  dedicated
fc1/39                                      1        8.0  dedicated
...

FC_switch_B_1# port-resource module
...
Port-Group 11
 Available dedicated buffers are 93
      
--------------------------------------------------------------------
Interfaces in the Port-Group       B2B Credit  Bandwidth  Rate Mode
                                     Buffers     (Gbps)
          
--------------------------------------------------------------------
fc1/37                                     32        8.0  dedicated
fc1/38                                      1        8.0  dedicated
fc1/39                                      1        8.0 dedicated
...