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# VPC Peering Connection (same cloud)

## Introduction

VPC peering lets users create direct IP connectivity between any two VPCs.
Direct connectivity between VPCs means that servers in a VPC can be reached
from the other VPC without the need for elastic IPs or traffic flowing through
the edge network.

* VPC peering is simply L3 connectivity realized using routing tables and
  IP connectivity.
* VPC peering can only be achieved between VPCs that do not have an address
  overlap (as the connectivity is based solely on routing).
* VPC peering is between exactly two VPCs in one Zadara region.
* VPC peering is subject to the Zadara Cloud Services permission scheme.
  This means that to create a peering connection, a user must have
  permissions in both VPCs.
* Unlike VPC peering in AWS, the Zadara Cloud Services implementation does
  not require the two ends of the peering connection to consent.
* A peer VPC can be referenced in a security group only by the peer’s CIDR.
* The VPC peering functionality can be used in a star topology with one central
  VPC and 3 peered VPCs.

## VPC peering implementation in zCompute

VPC peering is an additional router that lies between the peer VPCs.

This peering router is populated with the two VPCs’ addresses (CIDRs).

## Creating a Peering Connection

**To create a peering connection:**

1. Navigate to **Networking** > **Peering Connections**.
2. From the top toolbar, click **Peer VPC** and enter the following fields:
   * **Name** - name of peering connection.
   * **Description** - description of peering connection.
   * **Requester** - select requester VPC from pull down list.
   * **Accepter** - select accepter VPC from pull down list or by entering
     VPC ID shown in detailed VPC view in **Networking** > **VPCs**.
3. Click **OK**. The peering connection will appear in the list with status
   **Pending-Acceptance**.
4. To accept the peering request, click the status **Pending-Acceptance** and
   select **Accept** from top toolbar. The status should change to **Active**.

To allow traffic to flow, you must create routes in the relevant route tables.
A route can be to the entire VPC or to specific subnets.
The target of the route is the peering connection.

To create a route:

1. Navigate to **Networking** > **Route Tables**.
2. From top toolbar, select **Create** and enter the following fields:
   * **Name** - name of route table.
   * **Description** - description of route table.
   * **VPC** - VPC for one of the requester VPC.
3. Click **OK**. The route table is created.
4. Select the new route table from the displayed list, and from the lower
   toolbar, select the **Routes** tab and click **Create**.
5. In the **Create Route** dialog, select **Target Type** = **Peering Connections**
   and then select CIDR in the accepter VPC.
6. Click **OK**.

To confirm that a VPC peering connection is working, ping between two VM
instances in two different VPCs that have a VPC peering connection.