Solved: why encapsulation dot1q

Muhammad Thanveer · ‎03-14-2014

Hi Folks,

I have a question regarding encapsulation dot1q.

why we need to encapsulate for providing asigning an ip address.

interface Bundle-Ether10.1 (XR)

mtu 9216
ipv4 address X.X.X.X 255.255.255.254

encapsulation dot1q 2

interface port-channel20.10 (NX-OS)

mtu 9216
encapsulation dot1q 11

ip address X.X.X.X/31

no shutdown

interface Port-channel20.1 (IOS)
mtu 4470
encapsulation dot1q 20
ip add X.X.X.X 255.255.255.0

nikolasgeyer · ‎03-14-2014

In your examples, you are describing using one physical link to support multiple virtual networks using 802.1q tags for traffic separation/isolation. The 'encapsulation dot1q X' command is required to associate traffic with a particular 802.1q tag to a specific logical interface.

So in your IOS-XR example above, traffic entering the physical Bundle-Ether10 interface with an 802.1q tag of 2 will be terminated on the Bundle-Ether10.1 logical interface.

View solution in original post

nikolasgeyer · ‎03-14-2014

In your examples, you are describing using one physical link to support multiple virtual networks using 802.1q tags for traffic separation/isolation. The 'encapsulation dot1q X' command is required to associate traffic with a particular 802.1q tag to a specific logical interface.

So in your IOS-XR example above, traffic entering the physical Bundle-Ether10 interface with an 802.1q tag of 2 will be terminated on the Bundle-Ether10.1 logical interface.

Muhammad Thanveer · ‎03-14-2014

Your answer is fair enough to understand. Thanks