Layer 3 subinterface on Port-Channel on C9500

[NicolasDemonty]

Hello all,

I'm trying to configure Layer3 subinterfaces on port-channel on a C9500-48Y4C with version 16.9.4. However it seems the feature is not enabled or supported. When I try to apply this

interface Port-channel10.3000
encapsulation dot1Q 3000
ip address 10.229.0.2 255.255.255.0

!

I get the following error : Command Rejected: Sub-interface support is not enabled on port-channel

Does anyone have an idea about how to enable this feature or does anyone know whether it is supposed to be supported in later releases ?

thanks in advance

[balaji.bandi]

Looks there is some limitation as i was testing with Cat 9500 with Stackwise virtual, as per some release notes it was not supported.

let me do some test and come back to you.

here some guide lines same product line :

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9400/software/release/16-10/configuration_guide/vlan/b_1610_vlan_9400_cg/configuring_layer_3_subinterfaces.html

[NicolasDemonty]

Hi

feature is available in train 16.12 and above

kr

[balaji.bandi]

Sure at the stage 16.12.XX still not 5Start version, but this feature show stopper, can be tested.

[othydojo]

For what its worth, this feature is still not enabled five years later. However, the way we are going around this is by creating vlan interfaces and trunking the "allowed vlans" on the appropriate port-channels. Hopefully this helps someone looking at trying to accomplish sub-interfaces.

[Joseph W. Doherty]

Traditionally, your "work around" was how it was done on L3 switches.  Actually, reading the replies noting it can be done on some later IOS versions, somewhat surprised that you can do subinterfaces on a L3 switch routed port.

[kgras]

On the contrary, this feature is supported and requires "no switchport" command for the portchannel.

https://www.cisco.com/c/en/us/td/docs/switches/lan/catalyst9500/software/release/16-12/configuration_guide/vlan/b_1612_vlan_9500_cg/configuring_layer_3_subinterfaces.pdf

Device(config)# interface port-channel 2
Device(config-if)# no switchport
Device(config-if)# no ip address
Device(config-if)# exit
Device(config)# interface port-channel 2.10
Device(config-subif)# encapsulation dot1q 10
Decvice(config-subif)# ip address 10.10.10.11 255.255.255.0

[othydojo]

Sweet! Curious to know if there are advantages of having the sub-interface as a gateway, vs having an vlan interface, and vise versa? Is there any compute advantage or potential security upgrade?

[paul driver]

Hello
FYI -your out of luck im afraid 
Cat9k sub-interfaces supported from 6.12.X +   

[vishalbhandari]

@NicolasDemonty On IOS XE 16.9.4, sub-interfaces on a port-channel are not enabled by default on the C9500-48Y4C. You need to enable the feature manually. Try running the following command in global configuration mode:

platform qos port-channel-aggregate

After applying this, save the config and reload the switch. Then, try configuring the sub-interface again. If this doesn't work, consider upgrading to a newer IOS XE version, as later releases may provide better support for this feature.