z ‐ Connecting 2 VCNs in Same Region & Different Region - SanjeevOCI/Ocidocs GitHub Wiki

Connecting 2 VCNs in OCI

---

1. Same Region (Using Local Peering Gateway - LPG)

1. Create Local Peering Gateways (LPGs):

   • In VCN-1, create an LPG (e.g., LPG-VCN1).
   • In VCN-2, create another LPG (e.g., LPG-VCN2).

2. Establish Peering:

   • Go to LPG-VCN1 and establish peering with LPG-VCN2.

3. Update Route Tables:

   • In VCN-1, add a route in the route table of the app subnet:
     • Destination CIDR: CIDR of VCN-2.
     • Target: LPG-VCN1.
   • In VCN-2, add a route in the route table of the DB subnet:
     • Destination CIDR: CIDR of VCN-1.
     • Target: LPG-VCN2.

4. Update Security Lists:

   • In both VCNs, update security lists to allow ingress/egress traffic for the required ports and CIDRs.

---

2. Different Regions (Using Remote Peering Connection - RPC)

1. Create Dynamic Routing Gateways (DRGs):

   • In VCN-1, create a DRG and attach it to the VCN.
   • In VCN-2, create another DRG and attach it to the VCN.

2. Create Remote Peering Connections (RPCs):

   • In DRG-1 (for VCN-1), create an RPC (e.g., RPC-VCN1).
   • In DRG-2 (for VCN-2), create another RPC (e.g., RPC-VCN2).

3. Establish Peering:

   • Go to RPC-VCN1 and establish peering with RPC-VCN2.

4. Update Route Tables:

   • In VCN-1, add a route in the route table of the app subnet:
     • Destination CIDR: CIDR of VCN-2.
     • Target: DRG-1.
   • In VCN-2, add a route in the route table of the DB subnet:
     • Destination CIDR: CIDR of VCN-1.
     • Target: DRG-2.

5. Update Security Lists:

   • In both VCNs, update security lists to allow ingress/egress traffic for the required ports and CIDRs.

---

These steps ensure secure communication between VCNs in the same or different regions.