We have WS-C3650-24TS Catalyst L3 switch. I am trying to create a sub-interface on the ports but cannot make it work as the following error shows. Is there something I'm missing?

Sorry, newbie here.

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  • 1
    Try ‘no switchport’ first
    – Ron Trunk
    Mar 31 at 10:37
  • I tried, then used the same command. But I got the same error.
    – Carl
    Mar 31 at 10:40
  • Is this sub-interface creation switch specific (C3650), license specific (ipservices), or IOS specific (16.6.8)? Or is there some required command/configuration that I might be missing? Thanks
    – Carl
    Mar 31 at 11:06
  • 2
    Please post output as text, not as images, and use { and } to use prefomatted text.
    – Teun Vink
    Mar 31 at 13:01
  • 1
    On switches, you create SVIs, and you set the interfaces to trunks. You can specify which VLANs are on the trunks. It is not like a router interface where you use subinterfaces for the VLANs,
    – Ron Maupin
    Mar 31 at 13:34

Subinterfaces are used on routers and they can be used on some L3 switches. You need to configure the physical interface as a routed port or L3 port using no switchport, exit its config and then you can configure a subinterface.

On the 3650 series, VLAN subinterfaces on routed ports are not supported: https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst3650/software/release/3se/int_hw_components/configuration_guide/b_int_3se_3650_cg/b_int_3se_3650_cg_chapter_010.html

A routed port behaves like a regular router interface, except that it does not support VLAN subinterfaces.

Of course, the physical interface should also be enabled: no shutdown

Alternatively, use a switched interface and a VLAN with a switch virtual interface (SVI).

  • I did that as an alternative, that is working fine with us. But why can I not create this sub-interface?
    – Carl
    Mar 31 at 12:37

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