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