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ATM sub-interface routing


Currently My  DSL Circuits are configured on Bridged ATM sub-interfaces with IP at the BVI interface. The Hardware I am using is a 7206VXR. I am looking to see if the following is possible:

Have an ATM subinterface for the DSL connectivity and do the L3 on a vlan. For instance, have the ATM2/0.3050 use Interface G0/1.50 instead of a BVI interface.

Anyone know if this is possible and How?


4 Replies 4

paolo bevilacqua
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Yes. Under ATM subinf configure, "atm ip route-bridged", IP address, and eliminate bridge.

Hi Paolo,

Thanks for the reply. I have an additional question.

The 7206VXR G0/1 interface which is connected to a 3750 trunk port is configured like below:

interface GigabitEthernet0/1

no ip address

ip flow ingress

load-interval 30

duplex auto

speed auto

media-type rj45

no negotiation auto

no keepalive


interface GigabitEthernet0/1.3

encapsulation dot1Q 3

ip address x.x.x.x y.y.y.y


interface GigabitEthernet0/1.4

encapsulation dot1Q 4

no ip address



Can I make the ATM subint part of vlan 4? I would like to configure the ip address for this side of the connection on a layer 3 device connected to a 3750 port that is part of vlan 4. After "atm ip route-bridged", can I configure "encapsulation dot1Q 4"?


That would be a different thing - instead of terminating L3 on the 7200, you want to bridge packets to a 3750.

Note, I recommend that you always terminate ADSL connections on a true router, not a layer3 switch..

Anyway to do that, keep the bridge-group, but eliminate the BVI.

Thanks for the nice rating, and good luck!

Hi Paolo,

I did what you suggested:

1. Keep the bridge-group (bridge-group 4)

2. Eliminate the BVI

3. Made the GigabitEthernet0/1.4 subinterface part of the bridge-group:

interface GigabitEthernet0/1.4

encapsulation dot1Q 4

bridge-group 4

no ip address

When I created interface Vlan4 on the 3750 with ip address in the same subnet as the WAN interface of the remote DSL router, I could ping and telnet to the devices on both ends.

Thank you very much.

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