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New Member

Extending VLANs across routed interfaces


I'm trying to create a L3 core network. The core equipment will be Cisco 3750 enhanced. My idea is make each link between core 3750 a routed interface, with /30 IP addresses.

The problem is the customer needs some VLANs extended across the full enterprise. Is there any way to encapsulate the VLAN inside routed interface?

Thanks in advance.


Re: Extending VLANs across routed interfaces

check the following link for Understanding and Configuring VLAN Routing and Bridging on a Router Using the IRB Feature :

New Member

Re: Extending VLANs across routed interfaces

I realize this thread is 5+ years old, but I feel like commenting anyway.

If you want to encapsulate the vlan across that link, you won't be able to use routed interfaces.  You will need to use a layer 2 trunk(dot1q).  Therefore, I wouldn't bother with the /30 addresses unless you want to monitor that specific link by IP.  In that case, use a special VLAN just for those two interfaces and put your /30 addresses on the vlan interfaces.

If you want fast fail over on a layer 2 link, well then, use Rapid STP.  The goal should be to get rid of those flat VLANs that span the core and switch to your original plan of routed interfaces using EIGRP or OSPF.