# Peerings in AWS Cloud WAN
<a name="cloudwan-peerings"></a>

AWS Cloud WAN peering connections allow you to interconnect your core network edge with an AWS Transit Gateway in the same Region. Peering connections between Cloud WAN and transit gateways support dynamic routing with automatic exchange of routes using BGP. You can use route table attachments on the peering connection to selectively exchange routes between a specific transit gateway route table and a Cloud WAN network segment for end-to-end segmentation and network isolation.

The peering connection supports policy-based routing to implement segment isolation across peering connections. Using this capability, routes are selectively propagated between a route table in transit gateway and a core network segment. You first need to create the peering connection and associate a policy table to the transit gateway peering attachment. A policy table contains rules for matching network traffic by a specific route table or segment, and then maps traffic that matches the rule to a target route table for determining routing behavior. 

 When you create a peering connection, you can either create a new policy table or use an existing policy table for association with the peering attachment. As you create your route table attachments, the policy table is populated automatically with the policy rules that match network traffic by a segment or routing domain, and then maps the traffic that matches the rule to a target route table. For more information about transit gateway peering, see [Transit gateway peering attachments](https://docs.aws.amazon.com/vpc/latest/tgw/tgw-peering.html) in the *AWS Transit Gateway Guide*.

## Peering limitations
<a name="cloudwan-peerings-limits"></a>

Limits apply when creating a transit gateway peering connection between your transit gateways in AWS Cloud WAN. 

The following limitations apply when creating a peering: 
+ A transit gateway used for peering must be in the same Region as the core network.
+ The Autonomous System Number (ASN) of a transit gateway and the core network must be different.
+ A transit gateway connection to Cloud WAN only supports dynamically propagated routes. An error is returned if you try to add a static route.

**Topics**
+ [

## Peering limitations
](#cloudwan-peerings-limits)
+ [Create a peering](cloudwan-peerings-create.md)
+ [View peering details](cloudwan-peerings-view.md)
+ [Delete a peering](cloudwan-peerings-delete.md)
+ [Edit peering tags](cloudwan-peerings-edit.md)

# Create a peering in an AWS Cloud WAN core network
<a name="cloudwan-peerings-create"></a>

Create a transit gateway peering.

**Important**  
Before creating a peering, make sure that the account you use to create the peering has the following permissions:  
`ec2:CreateTransitGatewayPolicyTable`
`ec2:AcceptTransitGatewayPeeringAttachment`
`ec2:AssociateTransitGatewayPolicyTable`

**To create a peering**

1. Access the Network Manager console at [https://console.aws.amazon.com/networkmanager/home/](https://console.aws.amazon.com/networkmanager/home).

1. Under **Connectivity**, choose **Global networks**.

1. On the **Global networks** page, choose the global network ID.

1. Under **Core network** in the navigation pane, choose **Peerings**.

1. Choose **Create peering**.

1. (Optional) Enter a **name** identifying the peering.

1. From the **Edge location** dropdown list, choose the edge location where the peering is located.

1. From the **Transit gateway** dropdown list, choose a transit gateway to be used for the peering.
**Note**  
The core ASN and the transit gateway ASN must be unique. ASNs must be unique for peerings to succeed.

1. Choose one of the following **Associate policy table** options:
   + **New** — Creates a new policy routing table.
   + **Existing** — Allows you to associate this peering with an existing policy table. If you choose this option, you'll be prompted to choose an existing **Transit gateway policy table** to associate with the peering. For information on creating a transit gateway policy table, see [Transit Gateway policy tables](https://docs.aws.amazon.com/vpc/latest/tgw/tgw-policy-tables.html) in the *AWS Transit Gateway Guide*.

1. (Optional) If the transit gateway is not registered in your global network, choose **Register the specific transit gateway to the global network** to simultaneously register the transit gateway to the global network. If your transit gateway is already registered, this option does not display.

1. (Optional) In the **Tags** section, add **Key** and **Value** tags to help identify this resource. You can add multiple tags by choosing **Add tag**, or remove any tag by choosing **Remove tag**.

1. Choose **Create peering**.

   The **Create peering progress** displays the current status of the peering deployment. When deployment is complete, the **State** of the peering on the **Peerings** page displays **Available**. You can then use this peering to create a transit gateway route table attachment. See [Transit gateway route table attachments in AWS Cloud WAN](cloudwan-tgw-attachment.md) 

# View peering details in an AWS Cloud WAN core network
<a name="cloudwan-peerings-view"></a>

View information about a transit gateway used for peering.

**To view peering details**

1. Access the Network Manager console at [https://console.aws.amazon.com/networkmanager/home/](https://console.aws.amazon.com/networkmanager/home).

1. Under **Connectivity**, choose **Global networks**.

1. On the **Global networks** page, choose the global network ID.

1. Under **Core network** in the navigation pane, choose **Peerings**.

1. Choose the **Peering ID** of the peer that you want to view details for.

1. In the **Details** section, choose the **Resource ID** link.

   The **Transit gateways** page appears in a new window. Depending on your permissions, you can add or modify your transit gateways or transit gateway route tables. For more information on working with transit gateways, see the [https://docs.aws.amazon.com/vpc/latest/tgw/what-is-transit-gateway.html](https://docs.aws.amazon.com/vpc/latest/tgw/what-is-transit-gateway.html).

# Delete a peering from an AWS Cloud WAN core network
<a name="cloudwan-peerings-delete"></a>

Delete a transit gateway peering.

**To delete a peering**

1. Access the Network Manager console at [https://console.aws.amazon.com/networkmanager/home/](https://console.aws.amazon.com/networkmanager/home).

1. Under **Connectivity**, choose **Global networks**.

1. On the **Global networks** page, choose the global network ID.

1. Under **Core network** in the navigation pane, choose **Peerings**.

1. Choose the **Peering ID** of the peer that you want to delete.

1. Choose **Delete**.

1. In the confirmation box, choose **Delete**.

   The **Peering** page displays a confirmation that you deleted the transit gateway peering.

# Edit peering tags in an AWS Cloud WAN core network
<a name="cloudwan-peerings-edit"></a>

Edit the tags that are associated with transit gateway peering.

**To edit peering tags**

1. Access the Network Manager console at [https://console.aws.amazon.com/networkmanager/home/](https://console.aws.amazon.com/networkmanager/home).

1. Under **Connectivity**, choose **Global networks**.

1. On the **Global networks** page, choose the global network ID.

1. Under **Core network** in the navigation pane, choose **Peerings**.

1. Choose the **Peering ID** of the peer that you want to add or modify tags for.

1. In the **Peering name** section, choose the **Tags** tab.

1. Choose **Edit tags**.

1. Do any of the following:
   + To add a new tag, choose **Add tag**, and then add a new **Key** and **Value**.
   + To remove an existing tag, choose **Remove tag** for the tag that you want to delete.
   + To edit an existing tag, change the **Key** or **Value** text as needed.

1. Choose** Edit tags**.