IKEv1
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... IKE was originally defined in
[RFC2409] (which is called IKEv1 in this document) and is now
superseded by [RFC4306] (called IKEv2 ...
... RFC4301] assumes IKEv2, as some of the new features cannot be
negotiated using IKEv1. It is valid to negotiate multiple
traffic ...
... RFC4301]. This is
possible only with IKEv2. If IKEv1 is used, then multiple SAs
need to be set up, one for each traffic selector ...
... traffic selector.
Note that the existing implementations based on IKEv1 may already be
able to support the [RFC4301] features described in (1) and (2). If
...
... IKEv2 supports features useful for configuring and securing tunnels
not present with IKEv1.
1. IKEv2 ...
... As this does not provide Identity protection, main mode or aggressive
mode can be used with IKEv1.
...
... tunnels and doing so would make it easier for an
attacker to recover the keys. IKEv1 or IKEv2 must be used for
establishing the IPsec ...