No L2, is L3 an option?

[shinakuma123]

Hello guys

Scenario:

2 offices , Office A and office B (different floors apart).

Office A is on a different internal MGMT VLAN 10 (10.1.1.x/24) than office B which is on VLAN 20 (10.2.2.x /24). Each office has a L3 switch.

Currently there is a trunk between offices spanning those VLANs across, thus machines in either office can be set as either offices VLAN which grants them connectivity to each range.

Question:

The L2 trunk is now gone, and a machine in office B needs to communicate / be on office A's internal range VLAN. What options are possible here?

Each office still has a Layer 3 connection to each other (direct link) and are neighbors/peers from a routing POV. 

Is a L3 routed way possible? Please share your experience as have not come across situations like this and need a overview of all possible ways.

Thanks all

[Reza Sharifi]

Hi,

Since the L2 trunk is gone now and you still need communication between office -A and B, you can segment the network by putting each office in their own subnet.  Something like this:

office-A 10.10.10.0/24

office-B 10.10.11.0/24

office-a-------layer-3-/30--------office-b

Than have a /30 (layer-3) link between the 2 offices.  You can run static routes between the 2 offices or if you prefer you can use a routing protocol e.g OSPF.

HTH