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3D1L
Asked: 2010-09-29 07:15:54 +0800 CST

Do I have to use the same vlan number for a sub-internface name in a Cisco router?

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When creating a sub-interface for use with dot1q encapsulation. Do I have to match the name of the interface with the vlan number?

For example:

int g1/0/0.40
encap dot1q 40

or would this also work?

int g1/0/0.50
encap dot1q 40
networking vlan interface

3 Answers

  1. Best Answer

    Do I have to match the name of the interface with the vlan number?

    No, I don't believe so. It's just a standard convention (and one I'd highly recommend sticking to) to reduce confusion when reading or modifying the config.

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  2. Are you asking does the VLAN ID need to have anything to do with the IP range? If so then not at all, VLANs are a layer 2 function, they don't care about IP at all.

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  3. Agreed with ErikA, it keeps it easy to remember what sub-interface is mapped to what vlan. In some cases, sub-interfaces, vlans, and hsrp groups can use the same number to keep track of them all.

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