IPsec tunnel mode
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... There are many problems when using tunnel mode as implementations may
or may not model the IPsec tunnel mode SA as an interface as
...
... described in Appendix A.1.
If IPsec tunnel mode SA is not modeled as an interface (e.g., as of
...
... ISP as part of setting up
the IPsec tunnel mode SA. The details of these procedures are out of
scope for this memo.
...