09-04-2009 12:08 AM - edited 03-06-2019 07:35 AM
Hello,
We are actually running an MPLS network, and we need for a specific project to bridge one VLAN between a couple of routers and switches.
But, if we try to bridge the vlan on the routers using dot1q sub-interfaces on an interface which is also running an mpls sub-interface, it seems it is just not compatible:
example config:
interface GigabitEthernet1/0.505
encapsulation dot1Q 505
ip address 1.1.1.1 255.255.255.252
mpls ip
!
interface GigabitEthernet1/0.2598
encapsulation dot1Q 2598
Tryout 1:
Router#conf t
Router(config)#int Gi1/0.2598
Router(config-subif)#bridge-group 1
Interface has MPLS configuration
GigabitEthernet1/0.2598 cannot be configured into a Bridge Group
The reverse is also true:
Router(config)#int Gi1/0.505
Router(config-subif)#no mpls ip
Router(config-subif)#exit
Router(config)#int Gi1/0.2598
Router(config-subif)#bridge-group 1
Router(config)#int Gi1/0.505
Router(config-subif)#mpls ip
% MPLS not supported on interface GigabitEthernet1/0.505
Transparent bridging already configured
I naively thought that the configurations being applied on different sub-interfaces, in different dot1q domains, it would be somewhat segmented, and there would be no problems...
I'm more used to switches than routers, and I'd be curious to know the reasons for such a limitation on the 7200 platform (or in ios routers in general?).
Thanks,
Regards.
09-04-2009 05:32 AM
Hi,
Both feature are incompatible due to the way both feature are implemented in IOS.
If you want to transport a VLAN across your MPLS backbone, you should consider EoMPLS.
HTH
09-04-2009 12:42 PM
Hi,
Thanks for your answer,
> Both feature are incompatible due to the way both feature are implemented in IOS.
Yes, I sort of guessed that ;-) I was just curious about the soft/hard architectural reason behind it, I'll parse some technotes...
> If you want to transport a VLAN across your MPLS backbone, you should consider EoMPLS.
Sure, but the goal wasn't to transport the vlan accross the mpls backbone [sorry, I now realize that wasn't very clear in my post], just to add some redundancy at the edge of it [squared 2 7200 (in bb, running mpls) x 2 3560 (edge, no mpls)] using basic l2, "keeping it simple" [the two 7200 are directly connected].
Putting Eompls for this just add complexity, I guess I'll fallback to L3 redundancy. Sigh. When I first read about IRB, I was so happy that I had finally found the Catalyst SVI counterpart on routers platforms.
Thanks for your help,
Regards.
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