Closed amar-ibm closed 11 months ago
@amar-ibm Added a new topic on MTU to the documentation and linked from the VPN limitation section. If you have any comments on this new content, please contact me at dliburdi@us.ibm.com. Thank you for your feedback.
On a recent client connection, we had HTTPS connection issues over the VPN gateway connection from AWS using a route-based configuration. Client has MTU set to 9000 on all their machine images (jumbo frames), which caused issues when trying to make HTTPS connections in particular and send / receive data.
We late came to discover PMTUD is not supported on site to site gateways, nor are jumbo frames or MTU settings over a certain limit in AWS: https://docs.aws.amazon.com/vpn/latest/s2svpn/vpn-limits.html
This information should also be added to the IBM Cloud VPN limitations documentation for more effective pre-setup planning and avoid downstream debugging issues: https://cloud.ibm.com/docs/vpc?topic=vpc-vpn-limitations