2.2.11.1 Notify Payload
The Initiator role of the IKEv2 protocol can indicate its support of IKEv2 fragmentation and that it allows its use, by including a Notify payload of type IKEV2_FRAGMENTATION_SUPPORTED in the IKE_SA_INIT request message. If the Responder role also supports the fragmentation extension and allows its use, the Responder also includes this notification in its response message. This Initiator/Responder negotiation sequence is specified in section 2.3 of [RFC7383].
The following diagram shows the structure of the Notify payload.
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Next Payload |
RESERVED |
Payload_Length |
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Protocol ID |
SPI Size |
Notify_Message_Type |
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Next_Payload (1 byte): An identifier for the payload type of the next payload in the message. This field MUST be identical to the corresponding IKE field.
RESERVED (1 byte): This field MUST be set to zero. The responder (2) role MUST ignore this field on receipt. This is identical to IKE version 1 behavior.
Payload_Length (2 bytes): This field MUST be the length in bytes of the payload, including the Generic Payload header. This is identical in IKE version 1.
Protocol_ID_(=0) (1 byte): This field MUST be set to zero. The responder (2) role MUST ignore this field on receipt. This is identical to IKE version 1 behavior.
SPI_Size_(=0) (1 byte): This field MUST be set to zero, meaning that no Security Parameter Index (SPI) is present.
Notify_Message_Type (2 bytes): This field must be set to 16430, which is the value assigned for the IKEV2_FRAGMENTATION_SUPPORTED notification, per [RFC7383].