45_1: Overview

This document provides a step-by-step guide to validating routes in Oracle Cloud Infrastructure (OCI) using Dynamic Routing Gateway (DRG). It explains how DRG dynamically updates its route tables when new routes are advertised, ensuring seamless connectivity between Virtual Cloud Networks (VCNs), on-premises networks, and external peers.

45_2: Introduction to Dynamic Routing Gateway (DRG)

Oracle Cloud Infrastructure (OCI) provides Dynamic Routing Gateway (DRG) to facilitate connectivity between VCNs, on-premises networks, and third-party cloud providers. Unlike static routing, DRG supports dynamic routing using BGP (Border Gateway Protocol), enabling automatic updates to route tables when network changes occur.

45_3: Understanding Route Table Updates in DRG

When a new route is advertised (via BGP or a manual update in the network topology), the DRG automatically updates its route table to reflect the changes.

How DRG Updates Routes:

• DRG learns routes dynamically from VCNs, on-premises networks, or third-party clouds.
• The learned routes are automatically added to the DRG route table.
• The updated DRG route table propagates the new routes to connected resources.

Types of DRG Route Tables:

• VCN Attachment Route Table – Controls routing between the DRG and a specific VCN.
• Import Route Distribution Table – Defines which routes the DRG should learn from attached networks.
• Export Route Distribution Table – Determines which routes the DRG should advertise to connected resources.

45_4: Validating Route Updates in DRG

• Step1: Navigating

Menu --> Networking --> Customer Connectivity --> Dynamic routing gateway --> Select "HUB-SPOKE-DRG" [Hub_Spoke(NP_Test_VCN)_DRG]

• Step2: In the DRG, VCN attachment is created and attached. As a result, DRG automatically creates the route table to the VCN, as shown below

• Step3: Inside the autogenerated route table, there is a Route Distribution table, based on which the traffic flows, as shown below.

• Step4: In the Route Distribution table, "Match all" means that it will match any CIDR which is part of the attachment. This means that when we attach a VCN attachment, all the CIDR which is part of the VCN will get a route.

• Step5: When we view the Autogenerated Drg Route Table for VCN attachments, it has learnt the subnets, even though we have only attached it to VCN.

• Step6: Adding a new subnet in Spoke VCN(private subnet), it will also get reflected in the Route tables. Lets test it.

• Step7: Refresh the dynamic table