An interesting alternative way of subinterface

I was originally searching for a method to change the mac address for the subinterfaces on CSR1000v, and ran into this post. Apparently although the default behavior of subinterface inheriting the physical interface’s mac address can not be changed, with this method the goal can be achieved.

The method uses “service instance # ethernet”, along with “interface bdi #”. Example:

interface GigabitEthernet1
 no ip address
 negotiation auto
 service instance 1 ethernet
  encapsulation dot1q 10
  bridge-domain 10
 !
 service instance 2 ethernet
  encapsulation dot1q 20
  bridge-domain 20

interface BDI10
 mac-address aaaa.aaaa.aa10
 ip address 192.168.10.111 255.255.255.0
 encapsulation dot1Q 10
!
interface BDI20
 mac-address aaaa.aaaa.aa20
 ip address 192.168.20.111 255.255.255.0
 encapsulation dot1Q 20