Author: Jason Beattie
Transit routing in Oracle Cloud Infrastructure (OCI) using Dynamic Routing Gateways (DRGs), involves setting up a network architecture that enables communication between different virtual cloud networks (VCNs) or between on-premises networks and VCNs.
DRGs are used to facilitate this communication by providing a centralized point for managing routing between networks.
Below is a detailed guide based upon the above design:
1. Create Three Virtual Cloud Networks (VCNs):
VCN-Hub – 192.168.0.0/24
SN-Hub-Priv – 192.168.0.0/27
SN-Hub-Pub – 192.168.0.32/27
RT-Private-Hub
RT-Pub-Hub
VCN-Prod – 10.0.0.0/24
SN-Hub-Priv-app – 10.0.0.0/27
SN-Hub-Priv-db- 10.0.0.32/27
RT-Private-Prod-app
RT-Private-Prod-db
VCN-NonProd – 172.1.0.0/24
SN-Hub-Priv-app – 172.1.0.0/27
SN-Hub-Priv-db – 172.1.0.32/27
RT-Private-NonProd-app
RT-Private-NonProd-db
2. Create a DRG in the hub VCN.
3. Create a DRG attachment in all three VCNs and attach it to the DRG in the Hub VCN.
a. DRG-HUB-Att
b. DRG-Prod-Att
c. DRG-NonProd-Att
4. In the Hub Route Table (RT-Private-Hub) create the following Rules:
a. Prod-app – 10.0.0.0/24 – DRG-HUB
b. Prod-db – 10.0.0.32/24 – DRG-HUB
c. NonProd-app – 172.1.0.0/24 – DRG-HUB
d. NonProd-db – 172.1.0.32/24 – DRG-HUB
e. On-Premise – 172.12.13.0/24
5. In the Hub Route Table (RT-Pub-Hub) create the following Rules:
a. Prod-app – 10.0.0.0/24 – DRG-HUB
b. Prod-db – 10.0.0.32/24 – DRG-HUB
c. NonProd-app – 172.1.0.0/24 – DRG-HUB
d. NonProd-db – 172.1.0.32/24 – DRG-HUB
e. On-Premise – 172.12.13.0/24
6. In the NonProd-App route table (RT-Private-NonProd-app) create the following Rules:
a. Hub-VCN – 192.168.0.0/24 – DRG-NonProd-Att
b. Hub-VCN- 192.168.0.0/27 – DRG- NonProd-Att
c. Hub-VCN – 192.168.0.32/27 – DRG – NonProd-Att
d. On-Premise – 172.12.13.0/24 – DRG – NonProd-Att
7. In the NonProd-db route table (RT-Private-NonProd-db) create the following Rules:
a. Hub-VCN – 192.168.0.0/24 – DRG-NonProd-Att
b. Hub-VCN- 192.168.0.0/27 – DRG-NonProd-Att
c. Hub-VCN – 192.168.0.32/27 – DRG-NonProd-Att
d. On-Premise – 172.12.13.0/24 – DRG – NonProd-Att
8. In the Prod-App route table (RT-Private-Prod-app) create the following Rules:
a. Hub-VCN – 192.168.0.0/24 – DRG-Prod-Att
b. Hub-VCN- 192.168.0.0/27 – DRG-Prod-Att
c. Hub-VCN – 192.168.0.32/27 – DRG-Prod-Att
d. On-Premise – 172.12.13.0/24 – DRG –Prod-Att
9. In the Prod-db route table (RT-Private-Prod-db) create the following Rules:
a. Hub-VCN – 192.168.0.0/24 – DRG-Prod-Att
b. Hub-VCN- 192.168.0.0/27 – DRG-Prod-Att
c. Hub-VCN – 192.168.0.32/27 – DRG-Prod-Att
d. On-Premise – 172.12.13.0/24 – DRG –Prod-Att
10. In the route table section of the DRG, create a route table labled RT-Hub and add the following rules:
a. 192.168.0.0/27 – SN-Hub-Priv – Next hop DRG-HUB-Att
b. 192.168.0.32/27 – SN-Hub-Pub – Next hop DRG-HUB-Att
c. 10.0.0.0/24 – VCN-Prod – Next hop DRG-Prod-Att
d. 172.1.0.0/24 – VCN-NonProd – Next hop DRG-NonProd-Att
e. 172.12.13.0/24 – On-Premise – Next hop DRG-HUB-Att
11. Update the DRG route table of the Hub-VCN attachment to use the “RT-Hub” DRG route table.
12. Create the Customer Premise Equipment (CPE).
13. Create the Site-to-Site VPN (IPSEC) Tunnels to the on-premise firewalls as required.
14. To test the paths are working, add a security list or NSG rule that will allow egress and ingress into each resource or subnet.
i.e. add ICMP and test ping works from on premise to a IP within the OCI spokes (Prod or NonProd)
I hope you find my blog post on transit routing helpful! It worth noting that testing the above in a test or sandbox environment is heavily recommended.
Interested to know more?
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Jason Beattie
Senior Architect at Vertice
