5.1. Identification Payload

The Identification Payload is used to identify a group identity that will later be associated with Security Associations for the group. A group identity may map to a specific IP multicast group, or may specify a more general identifier, such as one that represents a set of related multicast streams.

The Identification Payload is defined as follows:

    0                   1                   2                   3
    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !  Next Payload !   RESERVED    !        Payload Length         !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   !   ID Type     !                    RESERVE2                   !
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   ~                     Identification Data                       ~
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

The Identification Payload fields are defined as follows:

• Next Payload (1 octet) -- Identifier for the payload type of the next payload in the message. If the current payload is the last in the message, this field will be zero (0).

• RESERVED (1 octet) -- Unused, must be zero (0).

• Payload Length (2 octets) -- Length, in octets, of the identification data, including the generic header.

• Identification Type (1 octet) -- Value describing the identity information found in the Identification Data field.

• RESERVED2 (2 octets) -- Unused, must be zero (0).

• Identification Data (variable length) -- Value, as indicated by the Identification Type.

5.1.1. Identification Type Values

The following table lists the assigned values for the Identification Type field found in the Identification Payload.

ID Type	Value
RESERVED	0 - 10
ID_KEY_ID	11
RESERVED	12 - 127
Private Use	128 - 255

5.1.1.1. ID_KEY_ID

In the context of a GDOI ID payload, ID_KEY_ID specifies a four (4)-octet group identifier.