Section B.12. Mobile IPv6 (Chapter 11, RFC 3775)

B.12. Mobile IPv6 (Chapter 11, RFC 3775)

The Mobility Header Type field identifies the type of Mobility message. Table B-29 is an overview of the Mobility messages.

Table B-29. Mobility message types


Message type



Binding Refresh Request

Sent by CN requesting the MN to update its binding.


Home Test Init

Sent by the MN to initiate the Return Routability Procedure and request a Home Keygen token from a CN. Sent to the CN through the tunnel via HA.


Care-of Test Init

Sent by the MN to initiate the Return Routability Procedure and request a Keygen token from a CN. Sent to the CN directly.


Home Test Message

Response to a Home Test Init message (type 1). Sent from the CN to MN. Contains a cookie and a Home Keygen token for the authorization in the Return Routability Process. Sent through the tunnel via HA.


Care-of Test Message

Response to Care-of Test Init message (type 2). Sent from CN to MN. Contains cookie and a Care-of Keygen token for the authorization in the Return Routability Procedure. Sent to the MN directly.


Binding Update

Sent by MN to notify a change of its care-of address. This message is explained in more detail later in the chapter.


Binding Ack

Sent as acknowledgement for receipt of a Binding Update message. This message is explained in more detail later in the chapter.


Binding Error

Sent by CN to signal an error related to mobility, such as an inappropriate attempt to use the Home Address destination option without an existing binding. The status field can have the following values:

1 = unkown binding for Home Address Destination option

2 = unrecognized MH type value


Fast Binding Update

Identical to binding update message, only with slightly different processing rules.


Fast Binding Ack

Sent as acknowledgement for receipt of a Fast Binding Update message.


Fast Neighbor Advertisement

Sent by mobile node to announce itself to its new access router.

Values 8, 9, and 10 have been assigned in RFC 4068 "Fast Handovers for Mobile IPv6." Find all message and option types as well as status codes at

Table B-30 shows the status values of the Binding Update. Values in the range of 0 to 127 indicate that the Binding Update has been accepted. Values above 128 indicate that the Binding Update has not been accepted.

Table B-30. Status values in the Binding Acknowledgement



Defined in


Binding Update accepted

RFC 3775


Accepted but prefix discovery necessary

RFC 3775


Reason unspecified

RFC 3775


Administratively prohibited

RFC 3775


Insufficient resources

RFC 3775


Home Registration not supported

RFC 3775


Not home subnet

RFC 3775


Not home agent for this mobile node

RFC 3775


Duplicate Address Detection failed

RFC 3775


Sequence number out of window

RFC 3775


Expired home nonce index

RFC 3775


Expired care-of nonce index

RFC 3775


Expired nonces

RFC 3775


Registration type change disallowed

RFC 3775


Mobile Router Operation not permitted

RFC 3963


Invalid Prefix

RFC 3963


Not Authorized for Prefix

RFC 3963


Forwarding Setup failed

RFC 3963



RFC 4285



RFC 4285



RFC 4285

Table B-31 shows an overview of the currently defined options for mobility messages.

Table B-31. Mobility options





Defined in

Type 0


Used to insert one padding Byte. This option has a special format; it contains only a type field, and no fields for length and data.

RFC 3775

Type 1


Used to insert two or more padding Bytes.

RFC 3775

Type 2

Length 2

Binding Refresh Advice

Indicates the remaining time until the MN should send a new home registration to HA. Only valid in Binding Acks sent from the HA in response to a home registration. The interval must be shorter than the lifetime value in the Binding Acknowledgement. A time unit is four seconds.

RFC 3775

Type 3

Length 16

Alternate Care-of address

Contains an address to use as the care-of address for the binding rather than using the Source address of the packet as the care-of address. Only in Binding Update messages.

RFC 3775

Type 4

Length 4

Nonce Indices

Has two additional fields besides the Type and Length field. The Home Nonce Index field tells the CN which nonce value to use when producing the Home Keygen Token. The Care-of Nonce field indicates the value for generating the Care-of Keygen Token. Valid only in the Binding Update message sent to a CN, and only when present together with a Binding Authorization Data option.

RFC 3775

Type 5

Length variable

Binding Authorization Data

Contains a cryptographic value that can be used to determine that the message in question comes from the right authority. Rules for calculating this value depend on the authorization procedure used. Must always be the last option in the MH. Only valid in Binding Update and Binding Acknowledgement. Used for the Return Routability process. In this case, the calculation of the Authenticator value is based on care-of address of MN, IPv6 address of CN, and data from the MH.

RFC 3775

Type 6

Mobile Network Prefix Option

Included in the Binding Update to indicate the prefix information for the Mobile Network to the HA.

RFC 3963

Type 7

Mobility Header Link-Layer Address option

Link-layer address option carried in an MH; used for Fast Handovers.

RFC 4068

Type 8


Optional suboption in the MH to specify the type of identifier used to identify the MN.

RFC 4283

Type 9


When receiving a binding update, the HA must check the timestamp field. If it is invalid, it replies with a binding acknowledgment including this status code.

RFC 4285

Type 10


Defines the type of mobility option.

RFC 4285

Type 201

Length 16

Home Address

Contains the home address of MN. Sent by MN when away from home to indicate its home address to the receiver. Carried in a Destination Options header. Must be inserted after Routing header and before Fragment, AH, or ESP header (if present).

RFC 3775

IPv6 Essentials
IPv6 Essentials
ISBN: 0596100582
EAN: 2147483647
Year: 2004
Pages: 156
Authors: Silvia Hagen

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