Restrictions for Configuring Layer 3 Subinterfaces
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Subinterfaces are not supported on StackWise Virtual Link.
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Subinterfaces with Software-Defined Access (SD-Access) is not supported.
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Subinterfaces, physical routed interfaces, and VLAN interfaces share the same hardware resources. The combination of all three interfaces cannot exceed the platform limits.
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For a given physical interface, only one subinterface can have the encapsulation as native.
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For a given physical interface, each subinterface should have a unique encapsulation ID.
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A physical interface cannot be used for Layer 3 services (no IP address configurations are supported on the physical interface) if one of the subinterface is configured as native.
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Do not configure encapsulation on the native VLAN of an IEEE 802.1Q trunk without the native keyword. Always use the native keyword of the dot1q vlan command when the VLAN ID is the ID of the IEEE 802.1Q native VLAN.
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If you configure normal-range VLANs on subinterfaces, you cannot change the VLAN Trunking Protocol (VTP) mode from Transparent.
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If a Layer 3 port has a subinterface configured with dot1q as the native VLAN, Cisco recommends not to configure routing related configuration on the Layer 3 port as it will hinder the functionality of the native VLAN subinterface.