FTD SUBINTERFACE CONNECTIVITY ISSUE

[isaaco001]

Dear community,

I have configured a subinterface (ip addresss, vlan) on a parent FTD interface. The connection goes to a switch trunk port. For some reason there is no connectivity between FTD and switch.

When I remove the subinterface and configure the parent interface as a normal interface then I can reach switch with not issues at all. Kindly assist to diagnose what's going on here! 

I have attached the running-config of FTD and screenshots of my configs.

Thanks! 

[nspasov · Accepted solution]

I suspect your issue is with using VLAN 1 on your sub-interface. VLAN 1 is the default native VLAN on trunk ports and your configuration suggests that you are using the default configuration. You can try one of the following:

1. Change your native vlan on the switch and firepower side to something else (e.g. 999)

2. Use a different vlan for your sub-interface

I hope this helps!

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