draft-ietf-hip-rfc5206-bis-02.txt   draft-ietf-hip-rfc5206-bis-03.txt 
Network Working Group P. Nikander Network Working Group T. Henderson, Ed.
Internet-Draft Ericsson Research NomadicLab Internet-Draft The Boeing Company
Obsoletes: 5206 (if approved) T. Henderson, Ed. Obsoletes: 5206 (if approved) C. Vogt
Intended status: Standards Track The Boeing Company Intended status: Standards Track J. Arkko
Expires: September 15, 2011 C. Vogt Expires: March 16, 2012 Ericsson Research NomadicLab
J. Arkko September 13, 2011
Ericsson Research NomadicLab
March 14, 2011
Host Mobility with the Host Identity Protocol Host Mobility with the Host Identity Protocol
draft-ietf-hip-rfc5206-bis-02 draft-ietf-hip-rfc5206-bis-03
Abstract Abstract
This document defines mobility extensions to the Host Identity This document defines mobility extensions to the Host Identity
Protocol (HIP). Specifically, this document defines a general Protocol (HIP). Specifically, this document defines a general
"LOCATOR" parameter for HIP messages that allows for a HIP host to "LOCATOR_SET" parameter for HIP messages that allows for a HIP host
notify peers about alternate addresses at which it may be reached. to notify peers about alternate addresses at which it may be reached.
This document also defines elements of procedure for mobility of a This document also defines elements of procedure for mobility of a
HIP host -- the process by which a host dynamically changes the HIP host -- the process by which a host dynamically changes the
primary locator that it uses to receive packets. While the same primary locator that it uses to receive packets. While the same
LOCATOR parameter can also be used to support end-host multihoming, LOCATOR_SET parameter can also be used to support end-host
detailed procedures are out of scope for this document. multihoming, detailed procedures are out of scope for this document.
This document obsoletes RFC 5206.
Status of This Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on September 15, 2011. This Internet-Draft will expire on March 16, 2012.
Copyright Notice Copyright Notice
Copyright (c) 2011 IETF Trust and the persons identified as the Copyright (c) 2011 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
This document is subject to BCP 78 and the IETF Trust's Legal This document is subject to BCP 78 and the IETF Trust's Legal
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
skipping to change at page 3, line 14 skipping to change at page 3, line 14
Table of Contents Table of Contents
1. Introduction and Scope . . . . . . . . . . . . . . . . . . . . 4 1. Introduction and Scope . . . . . . . . . . . . . . . . . . . . 4
2. Terminology and Conventions . . . . . . . . . . . . . . . . . 5 2. Terminology and Conventions . . . . . . . . . . . . . . . . . 5
3. Protocol Model . . . . . . . . . . . . . . . . . . . . . . . . 6 3. Protocol Model . . . . . . . . . . . . . . . . . . . . . . . . 6
3.1. Operating Environment . . . . . . . . . . . . . . . . . . 6 3.1. Operating Environment . . . . . . . . . . . . . . . . . . 6
3.1.1. Locator . . . . . . . . . . . . . . . . . . . . . . . 8 3.1.1. Locator . . . . . . . . . . . . . . . . . . . . . . . 8
3.1.2. Mobility Overview . . . . . . . . . . . . . . . . . . 8 3.1.2. Mobility Overview . . . . . . . . . . . . . . . . . . 8
3.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 9 3.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 9
3.2.1. Mobility with a Single SA Pair (No Rekeying) . . . . . 9 3.2.1. Mobility with a Single SA Pair (No Rekeying) . . . . . 10
3.2.2. Mobility with a Single SA Pair (Mobile-Initiated 3.2.2. Mobility with a Single SA Pair (Mobile-Initiated
Rekey) . . . . . . . . . . . . . . . . . . . . . . . . 11 Rekey) . . . . . . . . . . . . . . . . . . . . . . . . 11
3.2.3. Using LOCATORs across Addressing Realms . . . . . . . 11 3.2.3. Using LOCATOR_SETs across Addressing Realms . . . . . 12
3.2.4. Network Renumbering . . . . . . . . . . . . . . . . . 12 3.2.4. Network Renumbering . . . . . . . . . . . . . . . . . 12
3.3. Other Considerations . . . . . . . . . . . . . . . . . . . 12 3.3. Other Considerations . . . . . . . . . . . . . . . . . . . 12
3.3.1. Address Verification . . . . . . . . . . . . . . . . . 12 3.3.1. Address Verification . . . . . . . . . . . . . . . . . 12
3.3.2. Credit-Based Authorization . . . . . . . . . . . . . . 12 3.3.2. Credit-Based Authorization . . . . . . . . . . . . . . 13
3.3.3. Preferred Locator . . . . . . . . . . . . . . . . . . 14 3.3.3. Preferred Locator . . . . . . . . . . . . . . . . . . 14
4. LOCATOR Parameter Format . . . . . . . . . . . . . . . . . . . 14 4. LOCATOR_SET Parameter Format . . . . . . . . . . . . . . . . . 14
4.1. Traffic Type and Preferred Locator . . . . . . . . . . . . 16 4.1. Traffic Type and Preferred Locator . . . . . . . . . . . . 16
4.2. Locator Type and Locator . . . . . . . . . . . . . . . . . 16 4.2. Locator Type and Locator . . . . . . . . . . . . . . . . . 16
4.3. UPDATE Packet with Included LOCATOR . . . . . . . . . . . 17 4.3. UPDATE Packet with Included LOCATOR_SET . . . . . . . . . 17
5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . . 17 5. Processing Rules . . . . . . . . . . . . . . . . . . . . . . . 17
5.1. Locator Data Structure and Status . . . . . . . . . . . . 17 5.1. Locator Data Structure and Status . . . . . . . . . . . . 17
5.2. Sending LOCATORs . . . . . . . . . . . . . . . . . . . . . 18 5.2. Sending LOCATOR_SETs . . . . . . . . . . . . . . . . . . . 18
5.3. Handling Received LOCATORs . . . . . . . . . . . . . . . . 20 5.3. Handling Received LOCATOR_SETs . . . . . . . . . . . . . . 20
5.4. Verifying Address Reachability . . . . . . . . . . . . . . 22 5.4. Verifying Address Reachability . . . . . . . . . . . . . . 22
5.5. Changing the Preferred Locator . . . . . . . . . . . . . . 23 5.5. Changing the Preferred Locator . . . . . . . . . . . . . . 23
5.6. Credit-Based Authorization . . . . . . . . . . . . . . . . 24 5.6. Credit-Based Authorization . . . . . . . . . . . . . . . . 24
5.6.1. Handling Payload Packets . . . . . . . . . . . . . . . 24 5.6.1. Handling Payload Packets . . . . . . . . . . . . . . . 24
5.6.2. Credit Aging . . . . . . . . . . . . . . . . . . . . . 26 5.6.2. Credit Aging . . . . . . . . . . . . . . . . . . . . . 26
6. Security Considerations . . . . . . . . . . . . . . . . . . . 27 6. Security Considerations . . . . . . . . . . . . . . . . . . . 27
6.1. Impersonation Attacks . . . . . . . . . . . . . . . . . . 28 6.1. Impersonation Attacks . . . . . . . . . . . . . . . . . . 28
6.2. Denial-of-Service Attacks . . . . . . . . . . . . . . . . 29 6.2. Denial-of-Service Attacks . . . . . . . . . . . . . . . . 29
6.2.1. Flooding Attacks . . . . . . . . . . . . . . . . . . . 29 6.2.1. Flooding Attacks . . . . . . . . . . . . . . . . . . . 29
6.2.2. Memory/Computational-Exhaustion DoS Attacks . . . . . 29 6.2.2. Memory/Computational-Exhaustion DoS Attacks . . . . . 29
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[I-D.ietf-hip-rfc5201-bis]. [I-D.ietf-hip-rfc5201-bis].
One consequence of such a decoupling is that new solutions to One consequence of such a decoupling is that new solutions to
network-layer mobility and host multihoming are possible. There are network-layer mobility and host multihoming are possible. There are
potentially many variations of mobility and multihoming possible. potentially many variations of mobility and multihoming possible.
The scope of this document encompasses messaging and elements of The scope of this document encompasses messaging and elements of
procedure for basic network-level host mobility, leaving more procedure for basic network-level host mobility, leaving more
complicated scenarios and other variations for further study. More complicated scenarios and other variations for further study. More
specifically: specifically:
This document defines a generalized LOCATOR parameter for use in This document defines a generalized LOCATOR_SET parameter for use
HIP messages. The LOCATOR parameter allows a HIP host to notify a in HIP messages. The LOCATOR_SET parameter allows a HIP host to
peer about alternate addresses at which it is reachable. The notify a peer about alternate locators at which it is reachable.
LOCATORs may be merely IP addresses, or they may have additional The locators may be merely IP addresses, or they may have
multiplexing and demultiplexing context to aid the packet handling additional multiplexing and demultiplexing context to aid the
in the lower layers. For instance, an IP address may need to be packet handling in the lower layers. For instance, an IP address
paired with an ESP Security Parameter Index (SPI) so that packets may need to be paired with an ESP Security Parameter Index (SPI)
are sent on the correct SA for a given address. so that packets are sent on the correct SA for a given address.
This document also specifies the messaging and elements of This document also specifies the messaging and elements of
procedure for end-host mobility of a HIP host -- the sequential procedure for end-host mobility of a HIP host -- the sequential
change in the preferred IP address used to reach a host. In change in the preferred IP address used to reach a host. In
particular, message flows to enable successful host mobility, particular, message flows to enable successful host mobility,
including address verification methods, are defined herein. including address verification methods, are defined herein.
However, while the same LOCATOR parameter is intended to support However, while the same LOCATOR_SET parameter is intended to
host multihoming (parallel support of a number of addresses), and support host multihoming (parallel support of a number of
experimentation is encouraged, detailed elements of procedure for addresses), and experimentation is encouraged, detailed elements
host multihoming are out of scope. of procedure for host multihoming are out of scope.
While HIP can potentially be used with transports other than the ESP While HIP can potentially be used with transports other than the ESP
transport format [I-D.ietf-hip-rfc5202-bis], this document largely transport format [I-D.ietf-hip-rfc5202-bis], this document largely
assumes the use of ESP and leaves other transport formats for further assumes the use of ESP and leaves other transport formats for further
study. study.
There are a number of situations where the simple end-to-end There are a number of situations where the simple end-to-end
readdressing functionality is not sufficient. These include the readdressing functionality is not sufficient. These include the
initial reachability of a mobile host, location privacy, simultaneous initial reachability of a mobile host, location privacy, simultaneous
mobility of both hosts, and some modes of NAT traversal. In these mobility of both hosts, and some modes of NAT traversal. In these
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Transport-layer mobility triggers, and the proper transport response Transport-layer mobility triggers, and the proper transport response
to a HIP mobility or multihoming address change, are outside the to a HIP mobility or multihoming address change, are outside the
scope of this document. scope of this document.
2. Terminology and Conventions 2. Terminology and Conventions
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
LOCATOR. The name of a HIP parameter containing zero or more Locator LOCATOR_SET. The name of a HIP parameter containing zero or more
fields. This parameter's name is distinguished from the Locator Locator fields. This parameter's name is distinguished from the
fields embedded within it by the use of all capital letters. Locator fields embedded within it by the use of all capital
letters.
Locator. A name that controls how the packet is routed through the Locator. A name that controls how the packet is routed through the
network and demultiplexed by the end host. It may include a network and demultiplexed by the end host. It may include a
concatenation of traditional network addresses such as an IPv6 concatenation of traditional network addresses such as an IPv6
address and end-to-end identifiers such as an ESP SPI. It may address and end-to-end identifiers such as an ESP SPI. It may
also include transport port numbers or IPv6 Flow Labels as also include transport port numbers or IPv6 Flow Labels as
demultiplexing context, or it may simply be a network address. demultiplexing context, or it may simply be a network address.
Address. A name that denotes a point-of-attachment to the network. Address. A name that denotes a point-of-attachment to the network.
The two most common examples are an IPv4 address and an IPv6 The two most common examples are an IPv4 address and an IPv6
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Figure 1: HIP Deployment Model Figure 1: HIP Deployment Model
The general deployment model for HIP is shown above, assuming The general deployment model for HIP is shown above, assuming
operation in an end-to-end fashion. This document specifies operation in an end-to-end fashion. This document specifies
extensions to the HIP protocol to enable end-host mobility and basic extensions to the HIP protocol to enable end-host mobility and basic
multihoming. In summary, these extensions to the HIP base protocol multihoming. In summary, these extensions to the HIP base protocol
enable the signaling of new addressing information to the peer in HIP enable the signaling of new addressing information to the peer in HIP
messages. The messages are authenticated via a signature or keyed messages. The messages are authenticated via a signature or keyed
hash message authentication code (HMAC) based on its Host Identity. hash message authentication code (HMAC) based on its Host Identity.
This document specifies the format of this new addressing (LOCATOR) This document specifies the format of this new addressing
parameter, the procedures for sending and processing this parameter (LOCATOR_SET) parameter, the procedures for sending and processing
to enable basic host mobility, and procedures for a concurrent this parameter to enable basic host mobility, and procedures for a
address verification mechanism. concurrent address verification mechanism.
--------- ---------
| TCP | (sockets bound to HITs) | TCP | (sockets bound to HITs)
--------- ---------
| |
--------- ---------
----> | ESP | {HIT_s, HIT_d} <-> SPI ----> | ESP | {HIT_s, HIT_d} <-> SPI
| --------- | ---------
| | | |
---- --------- ---- ---------
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"locator". A locator specifies a point-of-attachment to the network "locator". A locator specifies a point-of-attachment to the network
but may also include additional end-to-end tunneling or per-host but may also include additional end-to-end tunneling or per-host
demultiplexing context that affects how packets are handled below the demultiplexing context that affects how packets are handled below the
logical HIP sublayer of the stack. This generalization is useful logical HIP sublayer of the stack. This generalization is useful
because IP addresses alone may not be sufficient to describe how because IP addresses alone may not be sufficient to describe how
packets should be handled below HIP. For example, in a host packets should be handled below HIP. For example, in a host
multihoming context, certain IP addresses may need to be associated multihoming context, certain IP addresses may need to be associated
with certain ESP SPIs to avoid violating the ESP anti-replay window. with certain ESP SPIs to avoid violating the ESP anti-replay window.
Addresses may also be affiliated with transport ports in certain Addresses may also be affiliated with transport ports in certain
tunneling scenarios. Locators may simply be traditional network tunneling scenarios. Locators may simply be traditional network
addresses. The format of the locator fields in the LOCATOR parameter addresses. The format of the locator fields in the LOCATOR_SET
is defined in Section 4. parameter is defined in Section 4.
3.1.2. Mobility Overview 3.1.2. Mobility Overview
When a host moves to another address, it notifies its peer of the new When a host moves to another address, it notifies its peer of the new
address by sending a HIP UPDATE packet containing a LOCATOR address by sending a HIP UPDATE packet containing a LOCATOR_SET
parameter. This UPDATE packet is acknowledged by the peer. For parameter. This UPDATE packet is acknowledged by the peer. For
reliability in the presence of packet loss, the UPDATE packet is reliability in the presence of packet loss, the UPDATE packet is
retransmitted as defined in the HIP protocol specification retransmitted as defined in the HIP protocol specification
[I-D.ietf-hip-rfc5201-bis]. The peer can authenticate the contents [I-D.ietf-hip-rfc5201-bis]. The peer can authenticate the contents
of the UPDATE packet based on the signature and keyed hash of the of the UPDATE packet based on the signature and keyed hash of the
packet. packet.
When using ESP Transport Format [I-D.ietf-hip-rfc5202-bis], the host When using ESP Transport Format [I-D.ietf-hip-rfc5202-bis], the host
may at the same time decide to rekey its security association and may at the same time decide to rekey its security association and
possibly generate a new Diffie-Hellman key; all of these actions are possibly generate a new Diffie-Hellman key; all of these actions are
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The scenarios below assume that the two hosts have completed a single The scenarios below assume that the two hosts have completed a single
HIP base exchange with each other. Both of the hosts therefore have HIP base exchange with each other. Both of the hosts therefore have
one incoming and one outgoing SA. Further, each SA uses the same one incoming and one outgoing SA. Further, each SA uses the same
pair of IP addresses, which are the ones used in the base exchange. pair of IP addresses, which are the ones used in the base exchange.
The readdressing protocol is an asymmetric protocol where a mobile The readdressing protocol is an asymmetric protocol where a mobile
host informs a peer host about changes of IP addresses on affected host informs a peer host about changes of IP addresses on affected
SPIs. The readdressing exchange is designed to be piggybacked on SPIs. The readdressing exchange is designed to be piggybacked on
existing HIP exchanges. The majority of the packets on which the existing HIP exchanges. The majority of the packets on which the
LOCATOR parameters are expected to be carried are UPDATE packets. LOCATOR_SET parameters are expected to be carried are UPDATE packets.
However, some implementations may want to experiment with sending However, some implementations may want to experiment with sending
LOCATOR parameters also on other packets, such as R1, I2, and NOTIFY. LOCATOR_SET parameters also on other packets, such as R1, I2, and
NOTIFY.
The scenarios below at times describe addresses as being in either an The scenarios below at times describe addresses as being in either an
ACTIVE, VERIFIED, or DEPRECATED state. From the perspective of a ACTIVE, VERIFIED, or DEPRECATED state. From the perspective of a
host, newly-learned addresses of the peer must be verified before put host, newly-learned addresses of the peer must be verified before put
into active service, and addresses removed by the peer are put into a into active service, and addresses removed by the peer are put into a
deprecated state. Under limited conditions described below deprecated state. Under limited conditions described below
(Section 5.6), an UNVERIFIED address may be used. The addressing (Section 5.6), an UNVERIFIED address may be used. The addressing
states are defined more formally in Section 5.1. states are defined more formally in Section 5.1.
Hosts that use link-local addresses as source addresses in their HIP Hosts that use link-local addresses as source addresses in their HIP
handshakes may not be reachable by a mobile peer. Such hosts SHOULD handshakes may not be reachable by a mobile peer. Such hosts SHOULD
provide a globally routable address either in the initial handshake provide a globally routable address either in the initial handshake
or via the LOCATOR parameter. or via the LOCATOR_SET parameter.
3.2.1. Mobility with a Single SA Pair (No Rekeying) 3.2.1. Mobility with a Single SA Pair (No Rekeying)
A mobile host must sometimes change an IP address bound to an A mobile host must sometimes change an IP address bound to an
interface. The change of an IP address might be needed due to a interface. The change of an IP address might be needed due to a
change in the advertised IPv6 prefixes on the link, a reconnected PPP change in the advertised IPv6 prefixes on the link, a reconnected PPP
link, a new DHCP lease, or an actual movement to another subnet. In link, a new DHCP lease, or an actual movement to another subnet. In
order to maintain its communication context, the host must inform its order to maintain its communication context, the host must inform its
peers about the new IP address. This first example considers the peers about the new IP address. This first example considers the
case in which the mobile host has only one interface, IP address, a case in which the mobile host has only one interface, IP address, a
single pair of SAs (one inbound, one outbound), and no rekeying single pair of SAs (one inbound, one outbound), and no rekeying
occurs on the SAs. We also assume that the new IP addresses are occurs on the SAs. We also assume that the new IP addresses are
within the same address family (IPv4 or IPv6) as the first address. within the same address family (IPv4 or IPv6) as the first address.
This is the simplest scenario, depicted in Figure 3. This is the simplest scenario, depicted in Figure 3.
Mobile Host Peer Host Mobile Host Peer Host
UPDATE(ESP_INFO, LOCATOR, SEQ) UPDATE(ESP_INFO, LOCATOR_SET, SEQ)
-----------------------------------> ----------------------------------->
UPDATE(ESP_INFO, SEQ, ACK, ECHO_REQUEST) UPDATE(ESP_INFO, SEQ, ACK, ECHO_REQUEST)
<----------------------------------- <-----------------------------------
UPDATE(ACK, ECHO_RESPONSE) UPDATE(ACK, ECHO_RESPONSE)
-----------------------------------> ----------------------------------->
Figure 3: Readdress without Rekeying, but with Address Check Figure 3: Readdress without Rekeying, but with Address Check
The steps of the packet processing are as follows: The steps of the packet processing are as follows:
1. The mobile host is disconnected from the peer host for a brief 1. The mobile host may be disconnected from the peer host for a
period of time while it switches from one IP address to another. brief period of time while it switches from one IP address to
Upon obtaining a new IP address, the mobile host sends a LOCATOR another; this case is sometimes referred to in the literature as
parameter to the peer host in an UPDATE message. The UPDATE a "break-before-make" case. The host may also obtain its new IP
message also contains an ESP_INFO parameter containing the values address before loosing the old one ("make-before-break" case).
of the old and new SPIs for a security association. In this In either case, upon obtaining a new IP address, the mobile host
case, the OLD SPI and NEW SPI parameters both are set to the sends a LOCATOR_SET parameter to the peer host in an UPDATE
value of the preexisting incoming SPI; this ESP_INFO does not message. The UPDATE message also contains an ESP_INFO parameter
trigger a rekeying event but is instead included for possible containing the values of the old and new SPIs for a security
parameter-inspecting middleboxes on the path. The LOCATOR association. In this case, the OLD SPI and NEW SPI parameters
parameter contains the new IP address (Locator Type of "1", both are set to the value of the preexisting incoming SPI; this
defined below) and a locator lifetime. The mobile host waits for ESP_INFO does not trigger a rekeying event but is instead
this UPDATE to be acknowledged, and retransmits if necessary, as included for possible parameter-inspecting middleboxes on the
specified in the base specification [I-D.ietf-hip-rfc5201-bis]. path. The LOCATOR_SET parameter contains the new IP address
(Locator Type of "1", defined below) and a locator lifetime. The
mobile host waits for this UPDATE to be acknowledged, and
retransmits if necessary, as specified in the base specification
[I-D.ietf-hip-rfc5201-bis].
2. The peer host receives the UPDATE, validates it, and updates any 2. The peer host receives the UPDATE, validates it, and updates any
local bindings between the HIP association and the mobile host's local bindings between the HIP association and the mobile host's
destination address. The peer host MUST perform an address destination address. The peer host MUST perform an address
verification by placing a nonce in the ECHO_REQUEST parameter of verification by placing a nonce in the ECHO_REQUEST parameter of
the UPDATE message sent back to the mobile host. It also the UPDATE message sent back to the mobile host. It also
includes an ESP_INFO parameter with the OLD SPI and NEW SPI includes an ESP_INFO parameter with the OLD SPI and NEW SPI
parameters both set to the value of the preexisting incoming SPI, parameters both set to the value of the preexisting incoming SPI,
and sends this UPDATE (with piggybacked acknowledgment) to the and sends this UPDATE (with piggybacked acknowledgment) to the
mobile host at its new address. The peer MAY use the new address mobile host at its new address. The peer MAY use the new address
skipping to change at page 11, line 33 skipping to change at page 11, line 41
SPI set to the previous SPI, the NEW SPI set to the desired new SPI SPI set to the previous SPI, the NEW SPI set to the desired new SPI
value for the incoming SA, and the KEYMAT Index desired. Optionally, value for the incoming SA, and the KEYMAT Index desired. Optionally,
the host may include a DIFFIE_HELLMAN parameter for a new Diffie- the host may include a DIFFIE_HELLMAN parameter for a new Diffie-
Hellman key. The peer completes the request for a rekey as is Hellman key. The peer completes the request for a rekey as is
normally done for HIP rekeying, except that the new address is kept normally done for HIP rekeying, except that the new address is kept
as UNVERIFIED until the UPDATE nonce challenge is received as as UNVERIFIED until the UPDATE nonce challenge is received as
described above. Figure 4 illustrates this scenario. described above. Figure 4 illustrates this scenario.
Mobile Host Peer Host Mobile Host Peer Host
UPDATE(ESP_INFO, LOCATOR, SEQ, [DIFFIE_HELLMAN]) UPDATE(ESP_INFO, LOCATOR_SET, SEQ, [DIFFIE_HELLMAN])
-----------------------------------> ----------------------------------->
UPDATE(ESP_INFO, SEQ, ACK, [DIFFIE_HELLMAN,] ECHO_REQUEST) UPDATE(ESP_INFO, SEQ, ACK, [DIFFIE_HELLMAN,] ECHO_REQUEST)
<----------------------------------- <-----------------------------------
UPDATE(ACK, ECHO_RESPONSE) UPDATE(ACK, ECHO_RESPONSE)
-----------------------------------> ----------------------------------->
Figure 4: Readdress with Mobile-Initiated Rekey Figure 4: Readdress with Mobile-Initiated Rekey
3.2.3. Using LOCATORs across Addressing Realms 3.2.3. Using LOCATOR_SETs across Addressing Realms
It is possible for HIP associations to migrate to a state in which It is possible for HIP associations to migrate to a state in which
both parties are only using locators in different addressing realms. both parties are only using locators in different addressing realms.
For example, the two hosts may initiate the HIP association when both For example, the two hosts may initiate the HIP association when both
are using IPv6 locators, then one host may loose its IPv6 are using IPv6 locators, then one host may loose its IPv6
connectivity and obtain an IPv4 address. In such a case, some type connectivity and obtain an IPv4 address. In such a case, some type
of mechanism for interworking between the different realms must be of mechanism for interworking between the different realms must be
employed; such techniques are outside the scope of the present text. employed; such techniques are outside the scope of the present text.
The basic problem in this example is that the host readdressing to The basic problem in this example is that the host readdressing to
IPv4 does not know a corresponding IPv4 address of the peer. This IPv4 does not know a corresponding IPv4 address of the peer. This
skipping to change at page 12, line 20 skipping to change at page 12, line 31
It is expected that IPv6 networks will be renumbered much more often It is expected that IPv6 networks will be renumbered much more often
than most IPv4 networks. From an end-host point of view, network than most IPv4 networks. From an end-host point of view, network
renumbering is similar to mobility. renumbering is similar to mobility.
3.3. Other Considerations 3.3. Other Considerations
3.3.1. Address Verification 3.3.1. Address Verification
When a HIP host receives a set of locators from another HIP host in a When a HIP host receives a set of locators from another HIP host in a
LOCATOR, it does not necessarily know whether the other host is LOCATOR_SET, it does not necessarily know whether the other host is
actually reachable at the claimed addresses. In fact, a malicious actually reachable at the claimed addresses. In fact, a malicious
peer host may be intentionally giving bogus addresses in order to peer host may be intentionally giving bogus addresses in order to
cause a packet flood towards the target addresses [RFC4225]. cause a packet flood towards the target addresses [RFC4225].
Likewise, viral software may have compromised the peer host, Likewise, viral software may have compromised the peer host,
programming it to redirect packets to the target addresses. Thus, programming it to redirect packets to the target addresses. Thus,
the HIP host must first check that the peer is reachable at the new the HIP host must first check that the peer is reachable at the new
address. address.
An additional potential benefit of performing address verification is An additional potential benefit of performing address verification is
to allow middleboxes in the network along the new path to obtain the to allow middleboxes in the network along the new path to obtain the
skipping to change at page 14, line 38 skipping to change at page 14, line 38
Figure 5: Readdressing Scenario Figure 5: Readdressing Scenario
3.3.3. Preferred Locator 3.3.3. Preferred Locator
When a host has multiple locators, the peer host must decide which to When a host has multiple locators, the peer host must decide which to
use for outbound packets. It may be that a host would prefer to use for outbound packets. It may be that a host would prefer to
receive data on a particular inbound interface. HIP allows a receive data on a particular inbound interface. HIP allows a
particular locator to be designated as a Preferred locator and particular locator to be designated as a Preferred locator and
communicated to the peer (see Section 4). communicated to the peer (see Section 4).
4. LOCATOR Parameter Format 4. LOCATOR_SET Parameter Format
The LOCATOR parameter is a critical parameter as defined by The LOCATOR_SET parameter is a critical parameter as defined by
[I-D.ietf-hip-rfc5201-bis]. It consists of the standard HIP [I-D.ietf-hip-rfc5201-bis]. It consists of the standard HIP
parameter Type and Length fields, plus zero or more Locator sub- parameter Type and Length fields, plus zero or more Locator sub-
parameters. Each Locator sub-parameter contains a Traffic Type, parameters. Each Locator sub-parameter contains a Traffic Type,
Locator Type, Locator Length, Preferred locator bit, Locator Locator Type, Locator Length, Preferred locator bit, Locator
Lifetime, and a Locator encoding. A LOCATOR containing zero Locator Lifetime, and a Locator encoding. A LOCATOR_SET containing zero
fields is permitted but has the effect of deprecating all addresses. Locator fields is permitted but has the effect of deprecating all
addresses.
0 1 2 3 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 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
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Type | Length | | Type | Length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Traffic Type | Locator Type | Locator Length | Reserved |P| | Traffic Type | Locator Type | Locator Length | Reserved |P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Locator Lifetime | | Locator Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
skipping to change at page 15, line 32 skipping to change at page 15, line 32
| Traffic Type | Locator Type | Locator Length | Reserved |P| | Traffic Type | Locator Type | Locator Length | Reserved |P|
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Locator Lifetime | | Locator Lifetime |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| Locator | | Locator |
| | | |
| | | |
| | | |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Figure 6: LOCATOR Parameter Format Figure 6: LOCATOR_SET Parameter Format
Type: 193 Type: 193
Length: Length in octets, excluding Type and Length fields, and Length: Length in octets, excluding Type and Length fields, and
excluding padding. excluding padding.
Traffic Type: Defines whether the locator pertains to HIP signaling, Traffic Type: Defines whether the locator pertains to HIP signaling,
user data, or both. user data, or both.
Locator Type: Defines the semantics of the Locator field. Locator Type: Defines the semantics of the Locator field.
skipping to change at page 17, line 14 skipping to change at page 17, line 14
0: An IPv6 address or an IPv4-in-IPv6 format IPv4 address [RFC4291] 0: An IPv6 address or an IPv4-in-IPv6 format IPv4 address [RFC4291]
(128 bits long). This locator type is defined primarily for non- (128 bits long). This locator type is defined primarily for non-
ESP-based usage. ESP-based usage.
1: The concatenation of an ESP SPI (first 32 bits) followed by an 1: The concatenation of an ESP SPI (first 32 bits) followed by an
IPv6 address or an IPv4-in-IPv6 format IPv4 address (an additional IPv6 address or an IPv4-in-IPv6 format IPv4 address (an additional
128 bits). This IP address is defined primarily for ESP-based 128 bits). This IP address is defined primarily for ESP-based
usage. usage.
4.3. UPDATE Packet with Included LOCATOR 4.3. UPDATE Packet with Included LOCATOR_SET
A number of combinations of parameters in an UPDATE packet are A number of combinations of parameters in an UPDATE packet are
possible (e.g., see Section 3.2). In this document, procedures are possible (e.g., see Section 3.2). In this document, procedures are
defined only for the case in which one LOCATOR and one ESP_INFO defined only for the case in which one LOCATOR_SET and one ESP_INFO
parameter is used in any HIP packet. Furthermore, the LOCATOR SHOULD parameter is used in any HIP packet. Furthermore, the LOCATOR_SET
list all of the locators that are active on the HIP association SHOULD list all of the locators that are active on the HIP
(including those on SAs not covered by the ESP_INFO parameter). Any association (including those on SAs not covered by the ESP_INFO
UPDATE packet that includes a LOCATOR parameter SHOULD include both parameter). Any UPDATE packet that includes a LOCATOR_SET parameter
an HMAC and a HIP_SIGNATURE parameter. The relationship between the SHOULD include both an HMAC and a HIP_SIGNATURE parameter. The
announced Locators and any ESP_INFO parameters present in the packet relationship between the announced Locators and any ESP_INFO
is defined in Section 5.2. The sending of multiple LOCATOR and/or parameters present in the packet is defined in Section 5.2. The
ESP_INFO parameters is for further study; receivers may wish to sending of multiple LOCATOR_SET and/or ESP_INFO parameters is for
experiment with supporting such a possibility. further study; receivers may wish to experiment with supporting such
a possibility.
5. Processing Rules 5. Processing Rules
This section describes rules for sending and receiving the LOCATOR This section describes rules for sending and receiving the
parameter, testing address reachability, and using Credit-Based LOCATOR_SET parameter, testing address reachability, and using
Authorization (CBA) on UNVERIFIED locators. Credit-Based Authorization (CBA) on UNVERIFIED locators.
5.1. Locator Data Structure and Status 5.1. Locator Data Structure and Status
In a typical implementation, each outgoing locator is represented by In a typical implementation, each outgoing locator is represented by
a piece of state that contains the following data: a piece of state that contains the following data:
o the actual bit pattern representing the locator, o the actual bit pattern representing the locator,
o the lifetime (seconds), o the lifetime (seconds),
o the status (UNVERIFIED, ACTIVE, DEPRECATED), o the status (UNVERIFIED, ACTIVE, DEPRECATED),
o the Traffic Type scope of the locator, and o the Traffic Type scope of the locator, and
o whether the locator is preferred for any particular scope. o whether the locator is preferred for any particular scope.
The status is used to track the reachability of the address embedded The status is used to track the reachability of the address embedded
within the LOCATOR parameter: within the LOCATOR_SET parameter:
UNVERIFIED indicates that the reachability of the address has not UNVERIFIED indicates that the reachability of the address has not
been verified yet, been verified yet,
ACTIVE indicates that the reachability of the address has been ACTIVE indicates that the reachability of the address has been
verified and the address has not been deprecated, verified and the address has not been deprecated,
DEPRECATED indicates that the locator lifetime has expired. DEPRECATED indicates that the locator lifetime has expired.
The following state changes are allowed: The following state changes are allowed:
skipping to change at page 18, line 42 skipping to change at page 18, line 42
A DEPRECATED address MUST NOT be changed to ACTIVE without first A DEPRECATED address MUST NOT be changed to ACTIVE without first
verifying its reachability. verifying its reachability.
Note that the state of whether or not a locator is preferred is not Note that the state of whether or not a locator is preferred is not
necessarily the same as the value of the Preferred bit in the Locator necessarily the same as the value of the Preferred bit in the Locator
sub-parameter received from the peer. Peers may recommend certain sub-parameter received from the peer. Peers may recommend certain
locators to be preferred, but the decision on whether to actually use locators to be preferred, but the decision on whether to actually use
a locator as a preferred locator is a local decision, possibly a locator as a preferred locator is a local decision, possibly
influenced by local policy. influenced by local policy.
5.2. Sending LOCATORs 5.2. Sending LOCATOR_SETs
The decision of when to send LOCATORs is basically a local policy The decision of when to send LOCATOR_SETs is basically a local policy
issue. However, it is RECOMMENDED that a host send a LOCATOR issue. However, it is RECOMMENDED that a host send a LOCATOR_SET
whenever it recognizes a change of its IP addresses in use on an whenever it recognizes a change of its IP addresses in use on an
active HIP association, and assumes that the change is going to last active HIP association, and assumes that the change is going to last
at least for a few seconds. Rapidly sending LOCATORs that force the at least for a few seconds. It is possible to delay the exposure of
peer to change the preferred address SHOULD be avoided. additional locators to the peer, and to send data from previously
unannounced locators, as might arise in certain mobility situations.
Rapidly sending LOCATOR_SETs that force the peer to change the
preferred address SHOULD be avoided.
When a host decides to inform its peers about changes in its IP When a host decides to inform its peers about changes in its IP
addresses, it has to decide how to group the various addresses with addresses, it has to decide how to group the various addresses with
SPIs. The grouping should consider also whether middlebox SPIs. The grouping should consider also whether middlebox
interaction requires sending the same LOCATOR in separate UPDATEs on interaction requires sending the same LOCATOR_SET in separate UPDATEs
different paths. Since each SPI is associated with a different on different paths. Since each SPI is associated with a different
Security Association, the grouping policy may also be based on ESP Security Association, the grouping policy may also be based on ESP
anti-replay protection considerations. In the typical case, simply anti-replay protection considerations. In the typical case, simply
basing the grouping on actual kernel level physical and logical basing the grouping on actual kernel level physical and logical
interfaces may be the best policy. Grouping policy is outside of the interfaces may be the best policy. Grouping policy is outside of the
scope of this document. scope of this document.
Note that the purpose of announcing IP addresses in a LOCATOR is to Note that the purpose of announcing IP addresses in a LOCATOR_SET is
provide connectivity between the communicating hosts. In most cases, to provide connectivity between the communicating hosts. In most
tunnels or virtual interfaces such as IPsec tunnel interfaces or cases, tunnels or virtual interfaces such as IPsec tunnel interfaces
Mobile IP home addresses provide sub-optimal connectivity. or Mobile IP home addresses provide sub-optimal connectivity.
Furthermore, it should be possible to replace most tunnels with HIP Furthermore, it should be possible to replace most tunnels with HIP
based "non-tunneling", therefore making most virtual interfaces based "non-tunneling", therefore making most virtual interfaces
fairly unnecessary in the future. Therefore, virtual interfaces fairly unnecessary in the future. Therefore, virtual interfaces
SHOULD NOT be announced in general. On the other hand, there are SHOULD NOT be announced in general. On the other hand, there are
clearly situations where tunnels are used for diagnostic and/or clearly situations where tunnels are used for diagnostic and/or
testing purposes. In such and other similar cases announcing the IP testing purposes. In such and other similar cases announcing the IP
addresses of virtual interfaces may be appropriate. addresses of virtual interfaces may be appropriate.
Hosts MUST NOT announce broadcast or multicast addresses in LOCATORs. Hosts MUST NOT announce broadcast or multicast addresses in
Link-local addresses MAY be announced to peers that are known to be LOCATOR_SETs. Link-local addresses MAY be announced to peers that
neighbors on the same link, such as when the IP destination address are known to be neighbors on the same link, such as when the IP
of a peer is also link-local. The announcement of link-local destination address of a peer is also link-local. The announcement
addresses in this case is a policy decision; link-local addresses of link-local addresses in this case is a policy decision; link-local
used as Preferred locators will create reachability problems when the addresses used as Preferred locators will create reachability
host moves to another link. In any case, link-local addresses MUST problems when the host moves to another link. In any case, link-
NOT be announced to a peer unless that peer is known to be on the local addresses MUST NOT be announced to a peer unless that peer is
same link. known to be on the same link.
Once the host has decided on the groups and assignment of addresses Once the host has decided on the groups and assignment of addresses
to the SPIs, it creates a LOCATOR parameter that serves as a complete to the SPIs, it creates a LOCATOR_SET parameter that serves as a
representation of the addresses and affiliated SPIs intended for complete representation of the addresses and affiliated SPIs intended
active use. We now describe a few cases introduced in Section 3.2. for active use. We now describe a few cases introduced in
We assume that the Traffic Type for each locator is set to "0" (other Section 3.2. We assume that the Traffic Type for each locator is set
values for Traffic Type may be specified in documents that separate to "0" (other values for Traffic Type may be specified in documents
the HIP control plane from data plane traffic). Other mobility cases that separate the HIP control plane from data plane traffic). Other
are possible but are left for further experimentation. mobility cases are possible but are left for further experimentation.
1. Host mobility with no multihoming and no rekeying. The mobile 1. Host mobility with no multihoming and no rekeying. The mobile
host creates a single UPDATE containing a single ESP_INFO with a host creates a single UPDATE containing a single ESP_INFO with a
single LOCATOR parameter. The ESP_INFO contains the current single LOCATOR_SET parameter. The ESP_INFO contains the current
value of the SPI in both the OLD SPI and NEW SPI fields. The value of the SPI in both the OLD SPI and NEW SPI fields. The
LOCATOR contains a single Locator with a "Locator Type" of "1"; LOCATOR_SET contains a single Locator with a "Locator Type" of
the SPI must match that of the ESP_INFO. The Preferred bit "1"; the SPI must match that of the ESP_INFO. The Preferred bit
SHOULD be set and the "Locator Lifetime" is set according to SHOULD be set and the "Locator Lifetime" is set according to
local policy. The UPDATE also contains a SEQ parameter as usual. local policy. The UPDATE also contains a SEQ parameter as usual.
This packet is retransmitted as defined in the HIP protocol This packet is retransmitted as defined in the HIP protocol
specification [I-D.ietf-hip-rfc5201-bis]. The UPDATE should be specification [I-D.ietf-hip-rfc5201-bis]. The UPDATE should be
sent to the peer's preferred IP address with an IP source address sent to the peer's preferred IP address with an IP source address
corresponding to the address in the LOCATOR parameter. corresponding to the address in the LOCATOR_SET parameter.
2. Host mobility with no multihoming but with rekeying. The mobile 2. Host mobility with no multihoming but with rekeying. The mobile
host creates a single UPDATE containing a single ESP_INFO with a host creates a single UPDATE containing a single ESP_INFO with a
single LOCATOR parameter (with a single address). The ESP_INFO single LOCATOR_SET parameter (with a single address). The
contains the current value of the SPI in the OLD SPI and the new ESP_INFO contains the current value of the SPI in the OLD SPI and
value of the SPI in the NEW SPI, and a KEYMAT Index as selected the new value of the SPI in the NEW SPI, and a KEYMAT Index as
by local policy. Optionally, the host may choose to initiate a selected by local policy. Optionally, the host may choose to
Diffie Hellman rekey by including a DIFFIE_HELLMAN parameter. initiate a Diffie Hellman rekey by including a DIFFIE_HELLMAN
The LOCATOR contains a single Locator with "Locator Type" of "1"; parameter. The LOCATOR_SET contains a single Locator with
the SPI must match that of the NEW SPI in the ESP_INFO. "Locator Type" of "1"; the SPI must match that of the NEW SPI in
Otherwise, the steps are identical to the case in which no the ESP_INFO. Otherwise, the steps are identical to the case in
rekeying is initiated. which no rekeying is initiated.
The sending of multiple LOCATORs, locators with Locator Type "0", and The sending of multiple LOCATOR_SETs, locators with Locator Type "0",
multiple ESP_INFO parameters is for further study. Note that the and multiple ESP_INFO parameters is for further study. Note that the
inclusion of LOCATOR in an R1 packet requires the use of Type "0" inclusion of LOCATOR_SET in an R1 packet requires the use of Type "0"
locators since no SAs are set up at that point. locators since no SAs are set up at that point.
5.3. Handling Received LOCATORs 5.3. Handling Received LOCATOR_SETs
A host SHOULD be prepared to receive a LOCATOR parameter in the A host SHOULD be prepared to receive a LOCATOR_SET parameter in the
following HIP packets: R1, I2, UPDATE, and NOTIFY. following HIP packets: R1, I2, UPDATE, and NOTIFY.
This document describes sending both ESP_INFO and LOCATOR parameters This document describes sending both ESP_INFO and LOCATOR_SET
in an UPDATE. The ESP_INFO parameter is included when there is a parameters in an UPDATE. The ESP_INFO parameter is included when
need to rekey or key a new SPI, and is otherwise included for the there is a need to rekey or key a new SPI, and is otherwise included
possible benefit of HIP-aware middleboxes. The LOCATOR parameter for the possible benefit of HIP-aware middleboxes. The LOCATOR_SET
contains a complete map of the locators that the host wishes to make parameter contains a complete map of the locators that the host
or keep active for the HIP association. wishes to make or keep active for the HIP association.
In general, the processing of a LOCATOR depends upon the packet type In general, the processing of a LOCATOR_SET depends upon the packet
in which it is included. Here, we describe only the case in which type in which it is included. Here, we describe only the case in
ESP_INFO is present and a single LOCATOR and ESP_INFO are sent in an which ESP_INFO is present and a single LOCATOR_SET and ESP_INFO are
UPDATE message; other cases are for further study. The steps below sent in an UPDATE message; other cases are for further study. The
cover each of the cases described in Section 5.2. steps below cover each of the cases described in Section 5.2.
The processing of ESP_INFO and LOCATOR parameters is intended to be The processing of ESP_INFO and LOCATOR_SET parameters is intended to
modular and support future generalization to the inclusion of be modular and support future generalization to the inclusion of
multiple ESP_INFO and/or multiple LOCATOR parameters. A host SHOULD multiple ESP_INFO and/or multiple LOCATOR_SET parameters. A host
first process the ESP_INFO before the LOCATOR, since the ESP_INFO may SHOULD first process the ESP_INFO before the LOCATOR_SET, since the
contain a new SPI value mapped to an existing SPI, while a Type "1" ESP_INFO may contain a new SPI value mapped to an existing SPI, while
locator will only contain a reference to the new SPI. a Type "1" locator will only contain a reference to the new SPI.
When a host receives a validated HIP UPDATE with a LOCATOR and When a host receives a validated HIP UPDATE with a LOCATOR_SET and
ESP_INFO parameter, it processes the ESP_INFO as follows. The ESP_INFO parameter, it processes the ESP_INFO as follows. The
ESP_INFO parameter indicates whether an SA is being rekeyed, created, ESP_INFO parameter indicates whether an SA is being rekeyed, created,
deprecated, or just identified for the benefit of middleboxes. The deprecated, or just identified for the benefit of middleboxes. The
host examines the OLD SPI and NEW SPI values in the ESP_INFO host examines the OLD SPI and NEW SPI values in the ESP_INFO
parameter: parameter:
1. (no rekeying) If the OLD SPI is equal to the NEW SPI and both 1. (no rekeying) If the OLD SPI is equal to the NEW SPI and both
correspond to an existing SPI, the ESP_INFO is gratuitous correspond to an existing SPI, the ESP_INFO is gratuitous
(provided for middleboxes) and no rekeying is necessary. (provided for middleboxes) and no rekeying is necessary.
2. (rekeying) If the OLD SPI indicates an existing SPI and the NEW 2. (rekeying) If the OLD SPI indicates an existing SPI and the NEW
SPI is a different non-zero value, the existing SA is being SPI is a different non-zero value, the existing SA is being
rekeyed and the host follows HIP ESP rekeying procedures by rekeyed and the host follows HIP ESP rekeying procedures by
creating a new outbound SA with an SPI corresponding to the NEW creating a new outbound SA with an SPI corresponding to the NEW
SPI, with no addresses bound to this SPI. Note that locators in SPI, with no addresses bound to this SPI. Note that locators in
the LOCATOR parameter will reference this new SPI instead of the the LOCATOR_SET parameter will reference this new SPI instead of
old SPI. the old SPI.
3. (new SA) If the OLD SPI value is zero and the NEW SPI is a new 3. (new SA) If the OLD SPI value is zero and the NEW SPI is a new
non-zero value, then a new SA is being requested by the peer. non-zero value, then a new SA is being requested by the peer.
This case is also treated like a rekeying event; the receiving This case is also treated like a rekeying event; the receiving
host must create a new SA and respond with an UPDATE ACK. host must create a new SA and respond with an UPDATE ACK.
4. (deprecating the SA) If the OLD SPI indicates an existing SPI and 4. (deprecating the SA) If the OLD SPI indicates an existing SPI and
the NEW SPI is zero, the SA is being deprecated and all locators the NEW SPI is zero, the SA is being deprecated and all locators
uniquely bound to the SPI are put into the DEPRECATED state. uniquely bound to the SPI are put into the DEPRECATED state.
If none of the above cases apply, a protocol error has occurred and If none of the above cases apply, a protocol error has occurred and
the processing of the UPDATE is stopped. the processing of the UPDATE is stopped.
Next, the locators in the LOCATOR parameter are processed. For each Next, the locators in the LOCATOR_SET parameter are processed. For
locator listed in the LOCATOR parameter, check that the address each locator listed in the LOCATOR_SET parameter, check that the
therein is a legal unicast or anycast address. That is, the address address therein is a legal unicast or anycast address. That is, the
MUST NOT be a broadcast or multicast address. Note that some address MUST NOT be a broadcast or multicast address. Note that some
implementations MAY accept addresses that indicate the local host, implementations MAY accept addresses that indicate the local host,
since it may be allowed that the host runs HIP with itself. since it may be allowed that the host runs HIP with itself.
The below assumes that all locators are of Type "1" with a Traffic The below assumes that all locators are of Type "1" with a Traffic
Type of "0"; other cases are for further study. Type of "0"; other cases are for further study.
For each Type "1" address listed in the LOCATOR parameter, the host For each Type "1" address listed in the LOCATOR_SET parameter, the
checks whether the address is already bound to the SPI indicated. If host checks whether the address is already bound to the SPI
the address is already bound, its lifetime is updated. If the status indicated. If the address is already bound, its lifetime is updated.
of the address is DEPRECATED, the status is changed to UNVERIFIED. If the status of the address is DEPRECATED, the status is changed to
If the address is not already bound, the address is added, and its UNVERIFIED. If the address is not already bound, the address is
status is set to UNVERIFIED. Mark all addresses corresponding to the added, and its status is set to UNVERIFIED. Mark all addresses
SPI that were NOT listed in the LOCATOR parameter as DEPRECATED. corresponding to the SPI that were NOT listed in the LOCATOR_SET
parameter as DEPRECATED.
As a result, at the end of processing, the addresses listed in the As a result, at the end of processing, the addresses listed in the
LOCATOR parameter have either a state of UNVERIFIED or ACTIVE, and LOCATOR_SET parameter have either a state of UNVERIFIED or ACTIVE,
any old addresses on the old SA not listed in the LOCATOR parameter and any old addresses on the old SA not listed in the LOCATOR_SET
have a state of DEPRECATED. parameter have a state of DEPRECATED.
Once the host has processed the locators, if the LOCATOR parameter Once the host has processed the locators, if the LOCATOR_SET
contains a new Preferred locator, the host SHOULD initiate a change parameter contains a new Preferred locator, the host SHOULD initiate
of the Preferred locator. This requires that the host first verifies a change of the Preferred locator. This requires that the host first
reachability of the associated address, and only then changes the verifies reachability of the associated address, and only then
Preferred locator; see Section 5.5. changes the Preferred locator; see Section 5.5.
If a host receives a locator with an unsupported Locator Type, and If a host receives a locator with an unsupported Locator Type, and
when such a locator is also declared to be the Preferred locator for when such a locator is also declared to be the Preferred locator for
the peer, the host SHOULD send a NOTIFY error with a Notify Message the peer, the host SHOULD send a NOTIFY error with a Notify Message
Type of LOCATOR_TYPE_UNSUPPORTED, with the Notification Data field Type of LOCATOR_TYPE_UNSUPPORTED, with the Notification Data field
containing the locator(s) that the receiver failed to process. containing the locator(s) that the receiver failed to process.
Otherwise, a host MAY send a NOTIFY error if a (non-preferred) Otherwise, a host MAY send a NOTIFY error if a (non-preferred)
locator with an unsupported Locator Type is received in a LOCATOR locator with an unsupported Locator Type is received in a LOCATOR_SET
parameter. parameter.
A host MAY add the source IP address of a received HIP packet as a
candidate locator for the peer even if it is not listed in the peer's
LOCATOR_SET, but it SHOULD prefer locators explicitly listed in the
LOCATOR_SET.
5.4. Verifying Address Reachability 5.4. Verifying Address Reachability
A host MUST verify the reachability of an UNVERIFIED address. The A host MUST verify the reachability of an UNVERIFIED address. The
status of a newly learned address MUST initially be set to UNVERIFIED status of a newly learned address MUST initially be set to UNVERIFIED
unless the new address is advertised in a R1 packet as a new unless the new address is advertised in a R1 packet as a new
Preferred locator. A host MAY also want to verify the reachability Preferred locator. A host MAY also want to verify the reachability
of an ACTIVE address again after some time, in which case it would of an ACTIVE address again after some time, in which case it would
set the status of the address to UNVERIFIED and reinitiate address set the status of the address to UNVERIFIED and reinitiate address
verification. verification.
A host typically starts the address-verification procedure by sending A host typically starts the address-verification procedure by sending
a nonce to the new address. For example, when the host is changing a nonce to the new address. For example, when the host is changing
its SPI and sending an ESP_INFO to the peer, the NEW SPI value SHOULD its SPI and sending an ESP_INFO to the peer, the NEW SPI value SHOULD
be random and the value MAY be copied into an ECHO_REQUEST sent in be random and the value MAY be copied into an ECHO_REQUEST sent in
the rekeying UPDATE. However, if the host is not changing its SPI, the rekeying UPDATE. However, if the host is not changing its SPI,
it MAY still use the ECHO_REQUEST parameter in an UPDATE message sent it MAY still use the ECHO_REQUEST parameter in an UPDATE message sent
to the new address. A host MAY also use other message exchanges as to the new address. A host MAY also use other message exchanges as
confirmation of the address reachability. confirmation of the address reachability.
Note that in the case of receiving a LOCATOR in an R1 and replying Note that in the case of receiving a LOCATOR_SET in an R1 and
with an I2 to the new address in the LOCATOR, receiving the replying with an I2 to the new address in the LOCATOR_SET, receiving
corresponding R2 is sufficient proof of reachability for the the corresponding R2 is sufficient proof of reachability for the
Responder's preferred address. Since further address verification of Responder's preferred address. Since further address verification of
such an address can impede the HIP-base exchange, a host MUST NOT such an address can impede the HIP-base exchange, a host MUST NOT
separately verify reachability of a new Preferred locator that was separately verify reachability of a new Preferred locator that was
received on an R1. received on an R1.
In some cases, it MAY be sufficient to use the arrival of data on a In some cases, it MAY be sufficient to use the arrival of data on a
newly advertised SA as implicit address reachability verification as newly advertised SA as implicit address reachability verification as
depicted in Figure 7, instead of waiting for the confirmation via a depicted in Figure 7, instead of waiting for the confirmation via a
HIP packet. In this case, a host advertising a new SPI as part of HIP packet. In this case, a host advertising a new SPI as part of
its address reachability check SHOULD be prepared to receive traffic its address reachability check SHOULD be prepared to receive traffic
skipping to change at page 23, line 36 skipping to change at page 23, line 43
Preferred locator while in UNVERIFIED status to the extent Credit- Preferred locator while in UNVERIFIED status to the extent Credit-
Based Authorization permits. Credit-Based Authorization is explained Based Authorization permits. Credit-Based Authorization is explained
in Section 5.6. Once address verification succeeds, the status of in Section 5.6. Once address verification succeeds, the status of
the new Preferred locator changes to ACTIVE. the new Preferred locator changes to ACTIVE.
5.5. Changing the Preferred Locator 5.5. Changing the Preferred Locator
A host MAY want to change the Preferred outgoing locator for A host MAY want to change the Preferred outgoing locator for
different reasons, e.g., because traffic information or ICMP error different reasons, e.g., because traffic information or ICMP error
messages indicate that the currently used preferred address may have messages indicate that the currently used preferred address may have
become unreachable. Another reason may be due to receiving a LOCATOR become unreachable. Another reason may be due to receiving a
parameter that has the "P" bit set. LOCATOR_SET parameter that has the "P" bit set.
To change the Preferred locator, the host initiates the following To change the Preferred locator, the host initiates the following
procedure: procedure:
1. If the new Preferred locator has ACTIVE status, the Preferred 1. If the new Preferred locator has ACTIVE status, the Preferred
locator is changed and the procedure succeeds. locator is changed and the procedure succeeds.
2. If the new Preferred locator has UNVERIFIED status, the host 2. If the new Preferred locator has UNVERIFIED status, the host
starts to verify its reachability. The host SHOULD use a starts to verify its reachability. The host SHOULD use a
different locator listed as ACTIVE until address verification different locator listed as ACTIVE until address verification
skipping to change at page 30, line 46 skipping to change at page 30, line 46
4. A HIP host attempts to steal a non-HIP host's session. A HIP 4. A HIP host attempts to steal a non-HIP host's session. A HIP
host could spoof the non-HIP host's IP address during the base host could spoof the non-HIP host's IP address during the base
exchange or set the non-HIP host's IP address as its preferred exchange or set the non-HIP host's IP address as its preferred
address via an UPDATE. Other possibilities exist, but a simple address via an UPDATE. Other possibilities exist, but a simple
solution is to prevent the use of HIP address check information solution is to prevent the use of HIP address check information
to influence non-HIP sessions. to influence non-HIP sessions.
7. IANA Considerations 7. IANA Considerations
This document defines a LOCATOR parameter for the Host Identity This document defines a LOCATOR_SET parameter for the Host Identity
Protocol [I-D.ietf-hip-rfc5201-bis]. This parameter is defined in Protocol [I-D.ietf-hip-rfc5201-bis]. This parameter is defined in
Section 4 with a Type of 193. Section 4 with a Type of 193.
This document also defines a LOCATOR_TYPE_UNSUPPORTED Notify Message This document also defines a LOCATOR_TYPE_UNSUPPORTED Notify Message
Type as defined in the Host Identity Protocol specification Type as defined in the Host Identity Protocol specification
[I-D.ietf-hip-rfc5201-bis]. This parameter is defined in Section 5.3 [I-D.ietf-hip-rfc5201-bis]. This parameter is defined in Section 5.3
with a value of 46. with a value of 46.
8. Authors and Acknowledgments 8. Authors and Acknowledgments
Pekka Nikander and Jari Arkko originated this document, and Christian Pekka Nikander and Jari Arkko originated this document, and Christian
Vogt and Thomas Henderson (editor) later joined as co-authors. Greg Vogt and Thomas Henderson (editor) later joined as co-authors. Greg
Perkins contributed the initial draft of the security section. Petri Perkins contributed the initial draft of the security section. Petri
Jokela was a co-author of the initial individual submission. Jokela was a co-author of the initial individual submission.
The authors thank Miika Komu, Mika Kousa, Jeff Ahrenholz, and Jan The authors thank Miika Komu, Mika Kousa, Jeff Ahrenholz, Jan Melen,
Melen for many improvements to the document. Baris Boyvat, and Samu Varjonen for many improvements to the
document.
9. References 9. References
9.1. Normative references 9.1. Normative references
[I-D.ietf-hip-rfc4423-bis] Moskowitz, R., "Host Identity Protocol [I-D.ietf-hip-rfc4423-bis] Moskowitz, R., "Host Identity Protocol
Architecture", Architecture",
draft-ietf-hip-rfc4423-bis-02 (work in draft-ietf-hip-rfc4423-bis-03 (work in
progress), February 2011. progress), September 2011.
[I-D.ietf-hip-rfc5201-bis] Moskowitz, R., Heer, T., Jokela, P., and [I-D.ietf-hip-rfc5201-bis] Moskowitz, R., Heer, T., Jokela, P., and
T. Henderson, "Host Identity Protocol T. Henderson, "Host Identity Protocol
Version 2 (HIPv2)", Version 2 (HIPv2)",
draft-ietf-hip-rfc5201-bis-05 (work in draft-ietf-hip-rfc5201-bis-06 (work in
progress), March 2011. progress), July 2011.
[I-D.ietf-hip-rfc5202-bis] Jokela, P., Moskowitz, R., Nikander, P., [I-D.ietf-hip-rfc5202-bis] Jokela, P., Moskowitz, R., Nikander, P.,
and J. Melen, "Using the Encapsulating and J. Melen, "Using the Encapsulating
Security Payload (ESP) Transport Format Security Payload (ESP) Transport Format
with the Host Identity Protocol (HIP)", with the Host Identity Protocol (HIP)",
draft-ietf-hip-rfc5202-bis-00 (work in draft-ietf-hip-rfc5202-bis-00 (work in
progress), September 2010. progress), September 2010.
[I-D.ietf-hip-rfc5204-bis] Laganier, J. and L. Eggert, "Host [I-D.ietf-hip-rfc5204-bis] Laganier, J. and L. Eggert, "Host
Identity Protocol (HIP) Rendezvous Identity Protocol (HIP) Rendezvous
skipping to change at page 32, line 41 skipping to change at page 32, line 41
To be removed upon publication To be removed upon publication
+----------+--------------------------------------------------------+ +----------+--------------------------------------------------------+
| Revision | Comments | | Revision | Comments |
+----------+--------------------------------------------------------+ +----------+--------------------------------------------------------+
| draft-00 | Initial version from RFC5206 xml (unchanged). | | draft-00 | Initial version from RFC5206 xml (unchanged). |
| draft-01 | Remove multihoming-specific text; no other changes. | | draft-01 | Remove multihoming-specific text; no other changes. |
| draft-02 | Update references to point to -bis drafts; no other | | draft-02 | Update references to point to -bis drafts; no other |
| | changes. | | | changes. |
| draft-03 | issue 4: add make before break use case |
| | issue 6: peer locator exposure policies |
| | issue 10: rename LOCATOR to LOCATOR_SET |
| | issue 14: use of UPDATE packet's IP address |
+----------+--------------------------------------------------------+ +----------+--------------------------------------------------------+
Authors' Addresses Authors' Addresses
Pekka Nikander
Ericsson Research NomadicLab
JORVAS FIN-02420
FINLAND
Phone: +358 9 299 1
EMail: pekka.nikander@nomadiclab.com
Thomas R. Henderson (editor) Thomas R. Henderson (editor)
The Boeing Company The Boeing Company
P.O. Box 3707 P.O. Box 3707
Seattle, WA Seattle, WA
USA USA
EMail: thomas.r.henderson@boeing.com EMail: thomas.r.henderson@boeing.com
Christian Vogt Christian Vogt
Ericsson Research NomadicLab Ericsson Research NomadicLab
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