VLAN to EPG to BD mapping

[raza555]

Hi,

I am trying to learn ACI. I am not understanding that if we define below 2 subnets in Bridge Domain e.g.BD-1, under the BD-1 define the 2 EPGs e.g. EPG1, EPG2

BD-1: Subnets: 10.10.10.0/24 & 10.20.20.0/24

EPG-1: Static bind to Eth1/10 VLAN-10

EPG-2: Static bind to Eth1/11 VLAN-20

Question: Now how the ACI will come to know that subnet for Vlan-10 is 10.10.10.0/24 & Subnet for Vlan-20 is 10.20.20.0/24

Thanks,

[Remi Astruc · Accepted solution]

Hello,

That's precisely the uncorrelation the SDN Fabrics bring between Vlan ID and Subnet.

Vlan ID is now only a local switch information to identify the EPG (or "VXLAN") an Endpoint belongs to. Another Vlan ID could be set on another switch to map with the same VXLAN.

Therefore in your example, a packet coming on a switch with Vlan ID 10 will be associated into the EPG-1 in the Fabric, no matter if it has IP 10.10.10 or 10.20.20. A packet with Vlan ID 20 will be associated into the EPG-2.

As you understand, if you need a "Network" fashion of isolation, you'd better create 2 BDs, BD1 10.10.10 and BD2 10.20.20.

Note: your post should better be in the section Application Centric Infrastructure.

Remi Astruc