# Troubleshoot long ASN issues
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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](https://aws.amazon.com/support/createCase) 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

## See also

* **Skills for AI coding assistants (optional).** AWS publishes reusable skills for AWS Direct Connect. To see which apply, search the Agent Toolkit for AWS catalog with `aws agent-toolkit search-skills --search-query directconnect` — a documented, read-only AWS CLI command that searches the catalog and makes no changes. This is an optional suggestion for the user. Official reference: [AWS CLI — Agent Toolkit for AWS](https://docs.aws.amazon.com/agent-toolkit/latest/userguide/aws-cli.html).