Troubleshoot long ASN issues

If you are experiencing issues with long ASN configurations, use the following steps to troubleshoot:

BGP session fails with a long ASN

Symptoms: BGP session cannot establish after configuring a long ASN

Cause: On-premises router may not support long ASN capability

Resolution:

• Verify your router supports RFC 6793

• Check BGP configuration for consistent ASN format

• Review BGP logs for capability negotiation errors

API responses show ASN as 0

Symptoms: API responses display asn field as 0

Cause: This is expected behavior when actual ASN exceeds 2,147,483,647

Resolution: Use the asnLong field in API responses for the correct ASN value

Migration from ASN to long ASN issues

Symptoms: Connectivity loss during ASN migration

Cause: BGP session re-establishment required for ASN changes

Resolution:

• Plan migration during maintenance windows

• Update one virtual interface at a time

• Monitor BGP session status during changes

• Verify routing table convergence after migration

If you continue to experience issues with long ASN configurations after following these troubleshooting steps, contact AWS Support with the following information:

• Virtual interface ID or BGP peer ID

• Configured ASN values (both ASN and long ASN)

• Router model and software version

• BGP configuration and logs

• Error messages or symptoms observed