understanding Q-in-Q configuration (802.1Q Tunneling), Cisco book

[**Hamid**]

Hi,

Can anyone introduce me to a Cisco book about Q-in-Q? Actually, I understand Q-in-Q, but I am a little confused using the 'second-dot1q' command.

For example, what is the difference between the 'encapsulation dot1q 100' command and the 'encapsulation dot1q 100 second-dot1q 200' command? I know that in the second command, we specify both the inner and outer tags. However, I have seen some websites where they did not use 'second-dot1q' at the end of the command in Q-in-Q configurations.

[M02@rt37]

Hello @**Hamid** 

Start by this reference:

https://www.cisco.com/en/US/docs/ios/lanswitch/configuration/guide/lsw_ieee_802.1q.html

[MHM Cisco World]

Normal trunk have only one tag  (802.1q)

The q-in-q have two tag 

One we called outer and other inner 

Each one have different tag' 

Second tag is use to config outer tag of frame 

MHM