InitialPacketSizeIPv4 and InitialPacketSizeIPv6 values larger than minimal requirement

[NOBLES5E]

Firstly, I would like to thank you for the great work you guys have been doing on this project.

While debugging an issue related to a node with a NIC MTU of 1230 not transferring packets, we found that the InitialPacketSizeIPv4 and InitialPacketSizeIPv6 are the cause of this issue.

Notably, these values are set to 1252 and 1232 respectively, which are larger than the minimal requirement for the best compatibility 1200.

Could you kindly shed some light on why these values were set at 1252 and 1232 and not at the 1200 mark as recommended for compatibility reasons?

[NOBLES5E]

Possibly related to #3385

[marten-seemann]

Using a higher initial packet size allows the server to send larger certificate chains, see https://www.fastly.com/blog/quic-handshake-tls-compression-certificates-extension-study for example.

The value of 1232 / 1252 is very conservative and shouldn't cause any problems on paths on the internet. For reference, Chrome chooses a much larger value (~1350 bytes, last time I checked).

[NOBLES5E]

Thanks!