IKE goes into DOS protection under the condition described in section 3.10.7.

Using the notation, as specified in [RFC2408] section 4.1.1, the generalized form of an IKE exchange using the DOS Protection extension is as shown in the following figure. For more information, see [RFC2409] section 5.

Figure 8: IKE using the DOS Protection extension

The description in this section uses the message numbers from the protocol sequence diagram.