Which two protocols can detect native vlan mismatch errors?

3 thoughts on “Which two protocols can detect native vlan mismatch errors?”

1. A and B

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2. A and B.

   The native VLAN must match on both sides of the trunk link for 802.1Q; otherwise the link will not work. If there is a native VLAN mismatch, Spanning Tree Protocol (STP) places the port in a port VLAN ID (PVID) inconsistent state and will not forward on the link, thus, STP can detect native VLAN mismatch. Answer D

   Additionally, Cisco Discovery Protocol (CDP) version 2 passes native VLAN information between Cisco switches. If you have a native VLAN mismatch, you will see CDP error messages on the console output like this:

   Dec 9 14:10:21: %CDP-4-NATIVE_VLAN_MISMATCH: Native VLAN mismatch discovered on FastEthernet0/1 (1), with FastEthernet0/2 (301)

   Therefore CDP can also detect native VLAN mismatch.

   Reference: http://www.ciscopress.com/articles/article.asp?p=29803&seqNum=3

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3. A and B are correct.

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