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Frequent Contributor

Nexus Host interface configuration

Dears,

Please find the attached screenshot of the configuration of HIF, i have a nexus 7K connecting to the Nexus 2k on whih i want to create a HIF, my question is very simple the FEX number as per the screenshot are 101 on both the swithces they can be different on both the switches or it has to be same,

AND also the portchannel numbers on both the swithces can be different or that also has to be same.

 

 

4 REPLIES 4
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Cisco Employee

Hi Adam,

 

If you are refering to single-homed FEXs, it's not a requirement to have same FEX number or port-channel number on the vpc peers. Example of perfectly working and supported topology:

 

Screen Shot 2017-09-10 at 23.38.27.png

 

 

 

 

 

 

 

 

 

 

 

Must be identical between peers:

  • vpc number configured under HIF (Host Interface) port-channel

Can be different between peers:

  • FEX-id
  • Fabric port-channel number
  • HIF interface number
  • HIF port-channel number

 

Of course, if would be more easily to administrate/operate/troubleshoot if the host port-channel is consistent on both sides. 

 

 

If we move our discussion to dual-homed FEXs, then the FEX numbering/configuration must be identical. This is a requirement and FEX will not come up on (at least on one side) if there is any configuration mismatch.

 

Screen Shot 2017-09-10 at 23.53.00.png

 

Must be identical between peers:

  • vpc number configured under HIF (Host Interface) port-channel
  • FEX-id 
  • HIF interface number
  • HIF port-channel number

Can be different between peers:

  • Fabric port-channel number

 

Hope it helps,

Sergiu

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Dears

 

From second scenario i moved to first scenario becz we were not able to create HIF when FEX is dual homed to N7K

 

i am falling in first secnario according to your reply and i have confugured same according to suggestion provided for first scenario..

while configuring in the logging i received the below error is this error becz of FEX ID different in both N7K

 

SW2-CORE %SATCTRL-FEX108-2-SATCTRL_FEX_MISCONFIG: FEX-108 is being configured as 107 on different switch
SW2-CORE last message repeated 104 times
SW2-CORE %SATCTRL-FEX108-2-SATCTRL_FEX_MISCONFIG: FEX-107 is being configured as 108 on different switch
SW2-CORE last message repeated 95 times

Thanks

Highlighted

Hi,

 

The logs indicates an inconsistency between the cableing and configuration. 

 

Start by verifying that your FEXs are indeed single homed: use "show fex" to quickly verify the FEX-id - SN relationship. Compare the outputs between the two vpc peers and make sure you did not configured, for example, same N2K as FEX107 on one N7K and as FEX108 on the second N7K.

 

 

If all looks good and issue persists, share the output of "show fex" and "show run int po 107-108" from both N7Ks.

 

Cheers,

Sergiu 

Highlighted

Dear,

the cables are connected as dual but the configuration is blank on the interface for the links which are dual, still it will affect.

thanks

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