Please consider dot1q frames tagged 100 circulating on a LAN (VLAN 100).
To go out onto the Internet, frames have to go through a PPPoE sub-interface which is configured as below:
interface GigabitEthernet0/0/0.1 encapsulation dot1Q 777 pppoe enable group global pppoe-client dial-pool-number 1
Frames, leaving the LAN to go out onto the Internet, get the 777 tag.
Can you explain what happens to the frames tagged 100 as they go through (or try to go through) this Gi0/0/0.1 sub-interface?
Are they dropped?
Is their 100 tag replaced with tag 777?
What's happening to them?
EDIT 1 - in response to Mike Pennington
Thank you for your answer which is very helpful.
You are right. I also have a Dialer interface configured as you say.
Given what you explain, I think that my frames from VLAN 100 are dropped.
As such, frames tagged with 100 entering this router will exit to the internet assuming:
1) They enter the router on another IP vlan 100 subinterface or SVI
Shall I create another sub-interface:
interface GigabitEthernet0/0/0.100 encapsulation dot1Q 100
What about the PPPoE link and the Dialer?
I can have only one PPPoE link and I guess only one Dialer interface.
2) They have the destination mac-address of the aforementioned subinterface
How can I tell that frames dot1q tagged 100 shall go through this sub-interface with its specific destination mac-address?
Is there a link that has to be made between the new sub-interface
GigabitEthernet0/0/0.100 and the LAN sub-interface
that is already configured and which is configured as:
interface GigabitEthernet0/0/1.100 description ***Router sub-interface for voice traffic*** encapsulation dot1Q 100 ip address 192.168.100.1 255.255.255.0 ip nat inside ip tcp adjust-mss 1452
3) There is a route in the router pointing that packet's destination IP address to the internet
Would you be so very kind to tell me how to configure this route?
Would this be a route from interface
GigabitEthernet0/0/1.100 to the Dialer interface?