Hi!
How do differ from each other IPsec over GRE, VTI over IPsec(IPSec VTI), GRE over IPsec tunnel mode?
What is described as GRE over IPsec tunnel mode in the picture is signed "IPsec over GRE Tunnel Mode".
What is described as IPsec tunnel mode with a VTI (sometimes just IPsec VTI) is labeled "IPsec Tunnel Mode" in the picture.
I tend to think that:
IPsec over GRE = GRE over IPsec tunnel mode
IPsec VTI is GRE over IPsec tunnel mode without GRE-IP-header. It is duplicated by the IPsec-IP-header and can be saved on this by adding tunnel mode ipsec {ipv4 | ipv6} to the config.
But I do not find a clear confirmation of this.
On the other hand, the terms seem to me to be incorrect, since IPsec over GRE implies that IPsec is enclosed in the GRE.
- but this is already GRE over IPsec (transport mode), and not vice versa.
In addition, when the original data or the original header is said, it is not always clear how original they are, since this concept is relative in the context of encapsulations.
I would be grateful if you could help me figure out how correct it is written in bold.
