Hi,

Virtual-Switch instance was always  a fascination for me, just for a simple fact that you could turn a Router to Bridge/Switch everything. Although there are many advantages and applications, I quickly wanted to write up the Lab scenario which I have Done. I always prefer seeing some simple things first and then may be do a deep-dive about the feature.

Requirement- Router-1 / 2/ 3 are all attached to VMX , they have to ping to each other through vMX and this has to happen via Instance Virtual-Switch. Now, someone who already knows about default-switch / Bridge-domain could have said why not use these, well this Post is going to Expand when we revisit of having Why we needed Virtual-Switch advantage in first place.

 

Below is the Topology

Topology

Ge-0/0/0 is connected to R1 , Ge-0/0/1 connected to R2, Ge-0/0/3 Connected to R3. Let see what we need to configure at a basic level for this to work

 

1_intf_outtputs

So far so Good, whats Next, as per the requirement we were to create a Virtual-Switch Instance

2_instance_creation

Everything is fine, but looks like communication is not yet established, the reason is simple, we have used something called Enterprise-Style definition. To put it simply, we have to configure a Bridge-Domain for these interfaces to be associated with Bridge-Domain of Vlan-id 100. There is something called Learning Domain where it gets associated to Bridge-Domain, but that is not the post about.

Lets Create a Bridge-Domain quickly for Vlan-id 100 and see if it changes anything, please do note the bridge-domain will now be the part of the Instance and here comes the beauty of the virtual-switch, you could have completely a different virtual-switch with same Vlan and it just works fine, re-call the Idea of VRF  / Routing-Instance now 😉

Fantastic!

3_final_output

Lets look at the configuration again along with Mac-Table generation

4_final_mac_output

Regards

Rakesh M