conref.md

copyright	years 2023, 2025
lastupdated	2025-07-25
keywords
subcollection	transit-gateway
content-type	conref

heading 1

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Route report considerations

{: #reuse-route-report-considerations}

• The AS path displayed in a route report provides a single zone perspective. If your source or destination spans different zones, the path length may vary. For instance, consider two direct links: one in DAL10 and the other in DAL12, both advertising the same AS path length toward a DAL-based transit gateway connected to a VPC or classic environment. When calling from a DAL10 virtual server instance:

  • The DAL10 direct link is preferred.
  • For connections originating from DAL12, the DAL12 direct link is preferred.
  • In the case of DAL13, you would either get ECMP routing, assuming your gateway is set up for it, or a single direct link would be used. However, during a BGP reset, it could switch to the other direct link.

• Overlapping routes are a common issue when configuring a transit gateway. If the routes from two or more connections overlap, traffic might not be routed as intended. For more information, see Addressing route conflicts.

• After a new virtual connection (VPC, Classic infrastructure, or Direct Link) reaches Active state, allow 5 minutes for the routes to be learned by your transit gateway. Generating a route report before all routes are learned results in a partial route report.

• If a connection exposes a route of 0.0.0.0/0, that route is ignored when computing overlapping prefixes.

• Only one report per gateway is available at any time. If you generate a new report, the old report is deleted.

• Older route reports might be inaccurate after you add or remove a connection. As a result, if you update routes within those connections, it is recommended that you generate a new route report.

• If one or more routes are denied by prefix filters, those routes don't appear in the route report.