Skip to content

[BGP] Bgp loop prevention info #22092

New issue

Have a question about this project? Sign up for a free GitHub account to open an issue and contact its maintainers and the community.

By clicking “Sign up for GitHub”, you agree to our terms of service and privacy statement. We’ll occasionally send you account related emails.

Already on GitHub? Sign in to your account

Merged
merged 5 commits into from
Apr 30, 2025
Merged
Changes from 1 commit
Commits
File filter

Filter by extension

Filter by extension

Conversations
Failed to load comments.
Loading
Jump to
Jump to file
Failed to load files.
Loading
Diff view
Diff view
Prev Previous commit
Next Next commit
refined text
  • Loading branch information
marciocloudflare committed Apr 30, 2025
commit 4e29174d99833a062ddfec9b926c2e35760dfb51
Original file line number Diff line number Diff line change
Expand Up @@ -279,7 +279,10 @@ By default, each BGP peering session will use the same Cloudflare-side ASN to re
Magic WAN customers should also be aware of the following:
- The customer chooses their device ASN, which must be different to the Cloudflare-side ASN.
- The Cloudflare side ASN will be included in the \`AS_PATH\` of announced routes to any BGP enabled interconnect.
- Customer announced \`AS_PATH\` is transitive between interconnects — that is, the origin or customer ASN is visible on the \`AS_PATH\` for the routes your CPE receives from Cloudflare in BGP. Default BGP loop prevention mechanisms will mean that routes are not accepted from the same ASN. For example, if you have two different Magic WAN-connected sites both using \`ASN65000\`, then site A will not learn routes coming from site B because of default BGP loop prevention behavior. For routing between private networks using Magic WAN, you should assign a unique ASN for each network/site, or configure the edge CPE to accept BGP-learned routes containing its local ASN.
- The customer-announced \`AS_PATH\` is transitive between interconnects — meaning the origin (customer) ASN is visible in the \`AS_PATH\` of routes received from Cloudflare via BGP. Due to default BGP loop prevention mechanisms, a router will reject any route that contains its own ASN in the \`AS_PATH\`. For example, if two Magic WAN-connected sites both use \`ASN 65000\`, site A will not accept routes from site B, and vice versa, because each site sees its own ASN in the advertised \`AS_PATH\`. <br />
To enable routing between private networks over Magic WAN, you should either:
- Assign a unique ASN to each site/network, or
- Configure your edge CPE to accept BGP routes that include its own ASN in the \`AS_PATH\`.
`}
inline={false}
/>
Expand Down
Loading