@Soeb Bohari
Thank you for reaching out to Microsoft Q&A. I understand that you are having issues with BGP Flapping over Azure S2S VPN and want to know how to go about troubleshooting the same.
I see that the S2S VPN itself stays stable. Can you confirm the following to further troubleshoot the issue?
- Are you able to ping the Azure BGP Peer IP from the customer side Peer IP when the issue happens?
- What state does BGP go to when this issue occurs? (You can get the BGP Status using this powershell command on Azure side) https://learn.microsoft.com/en-us/azure/vpn-gateway/bgp-diagnostics#powershell
- Are you able to request any BGP/TCP logs from your customer side device?
On Azure side, you can check the BGP status using the Powershell command as mentioned above. You can also check the BGP Peers and their status on the Azure Portal as shown here.
Further, you can check the advertised routes and learned routes as seen from here. If you need more information regarding or in depth BGP logs, you will need to contact Azure Support for the same. Looking forward to your reply. Thank you!