draft-ietf-hip-mm-04.txt   draft-ietf-hip-mm-05.txt 
Network Working Group T. Henderson (editor) Network Working Group T. Henderson (editor)
Internet-Draft The Boeing Company Internet-Draft The Boeing Company
Expires: December 25, 2006 June 23, 2006 Expires: September 3, 2007 March 2, 2007
End-Host Mobility and Multihoming with the Host Identity Protocol End-Host Mobility and Multihoming with the Host Identity Protocol
draft-ietf-hip-mm-04 draft-ietf-hip-mm-05
Status of this Memo Status of this Memo
By submitting this Internet-Draft, each author represents that any By submitting this Internet-Draft, each author represents that any
applicable patent or other IPR claims of which he or she is aware applicable patent or other IPR claims of which he or she is aware
have been or will be disclosed, and any of which he or she becomes have been or will be disclosed, and any of which he or she becomes
aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
skipping to change at page 1, line 33 skipping to change at page 1, line 33
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
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The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
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This Internet-Draft will expire on December 25, 2006. This Internet-Draft will expire on September 3, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The IETF Trust (2007).
Abstract Abstract
This document defines mobility and multihoming extensions to the Host This document defines mobility and multihoming extensions to the Host
Identity Protocol (HIP). Specifically, this document defines a Identity Protocol (HIP). Specifically, this document defines a
general "LOCATOR" parameter for HIP messages that allows for a HIP general "LOCATOR" parameter for HIP messages that allows for a HIP
host to notify peers about alternate addresses at which it may be host to notify peers about alternate addresses at which it may be
reached. This document also defines elements of procedure for reached. This document also defines elements of procedure for
mobility of a HIP host-- the process by which a host dynamically mobility of a HIP host-- the process by which a host dynamically
changes the primary locator that it uses to receive packets. While changes the primary locator that it uses to receive packets. While
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3.1.1. Locator . . . . . . . . . . . . . . . . . . . . . . . 9 3.1.1. Locator . . . . . . . . . . . . . . . . . . . . . . . 9
3.1.2. Mobility overview . . . . . . . . . . . . . . . . . . 9 3.1.2. Mobility overview . . . . . . . . . . . . . . . . . . 9
3.1.3. Multihoming overview . . . . . . . . . . . . . . . . . 10 3.1.3. Multihoming overview . . . . . . . . . . . . . . . . . 10
3.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 10 3.2. Protocol Overview . . . . . . . . . . . . . . . . . . . . 10
3.2.1. Mobility with single SA pair (no rekeying) . . . . . . 11 3.2.1. Mobility with single SA pair (no rekeying) . . . . . . 11
3.2.2. Mobility with single SA pair (mobile-initiated 3.2.2. Mobility with single SA pair (mobile-initiated
rekey) . . . . . . . . . . . . . . . . . . . . . . . . 12 rekey) . . . . . . . . . . . . . . . . . . . . . . . . 12
3.2.3. Host multihoming . . . . . . . . . . . . . . . . . . . 13 3.2.3. Host multihoming . . . . . . . . . . . . . . . . . . . 13
3.2.4. Site multihoming . . . . . . . . . . . . . . . . . . . 14 3.2.4. Site multihoming . . . . . . . . . . . . . . . . . . . 14
3.2.5. Dual host multihoming . . . . . . . . . . . . . . . . 15 3.2.5. Dual host multihoming . . . . . . . . . . . . . . . . 15
3.2.6. Combined mobility and multihoming . . . . . . . . . . 15 3.2.6. Combined mobility and multihoming . . . . . . . . . . 16
3.2.7. Using LOCATORs across addressing realms . . . . . . . 16 3.2.7. Using LOCATORs across addressing realms . . . . . . . 16
3.2.8. Network renumbering . . . . . . . . . . . . . . . . . 16 3.2.8. Network renumbering . . . . . . . . . . . . . . . . . 16
3.2.9. Initiating the protocol in R1 or I2 . . . . . . . . . 16 3.2.9. Initiating the protocol in R1 or I2 . . . . . . . . . 16
3.3. Other Considerations . . . . . . . . . . . . . . . . . . . 17 3.3. Other Considerations . . . . . . . . . . . . . . . . . . . 18
3.3.1. Address Verification . . . . . . . . . . . . . . . . . 18 3.3.1. Address Verification . . . . . . . . . . . . . . . . . 18
3.3.2. Credit-Based Authorization . . . . . . . . . . . . . . 18 3.3.2. Credit-Based Authorization . . . . . . . . . . . . . . 18
3.3.3. Preferred locator . . . . . . . . . . . . . . . . . . 19 3.3.3. Preferred locator . . . . . . . . . . . . . . . . . . 19
3.3.4. Interaction with Security Associations . . . . . . . . 20 3.3.4. Interaction with Security Associations . . . . . . . . 20
4. LOCATOR parameter format . . . . . . . . . . . . . . . . . . . 23 4. LOCATOR parameter format . . . . . . . . . . . . . . . . . . . 23
4.1. Traffic Type and Preferred locator . . . . . . . . . . . . 24 4.1. Traffic Type and Preferred locator . . . . . . . . . . . . 24
4.2. Locator Type and Locator . . . . . . . . . . . . . . . . . 25 4.2. Locator Type and Locator . . . . . . . . . . . . . . . . . 25
4.3. UPDATE packet with included LOCATOR . . . . . . . . . . . 25 4.3. UPDATE packet with included LOCATOR . . . . . . . . . . . 25
5. Processing rules . . . . . . . . . . . . . . . . . . . . . . . 26 5. Processing rules . . . . . . . . . . . . . . . . . . . . . . . 26
5.1. Locator data structure and status . . . . . . . . . . . . 26 5.1. Locator data structure and status . . . . . . . . . . . . 26
5.2. Sending LOCATORs . . . . . . . . . . . . . . . . . . . . . 27 5.2. Sending LOCATORs . . . . . . . . . . . . . . . . . . . . . 27
5.3. Handling received LOCATORs . . . . . . . . . . . . . . . . 29 5.3. Handling received LOCATORs . . . . . . . . . . . . . . . . 29
5.4. Verifying address reachability . . . . . . . . . . . . . . 30 5.4. Verifying address reachability . . . . . . . . . . . . . . 31
5.5. Changing the Preferred locator . . . . . . . . . . . . . . 31 5.5. Changing the Preferred locator . . . . . . . . . . . . . . 32
5.6. Credit-Based Authorization . . . . . . . . . . . . . . . . 32 5.6. Credit-Based Authorization . . . . . . . . . . . . . . . . 33
5.6.1. Handling Payload Packets . . . . . . . . . . . . . . . 32 5.6.1. Handling Payload Packets . . . . . . . . . . . . . . . 33
5.6.2. Credit Aging . . . . . . . . . . . . . . . . . . . . . 34 5.6.2. Credit Aging . . . . . . . . . . . . . . . . . . . . . 35
6. Security Considerations . . . . . . . . . . . . . . . . . . . 36 6. Security Considerations . . . . . . . . . . . . . . . . . . . 37
6.1. Impersonation attacks . . . . . . . . . . . . . . . . . . 36 6.1. Impersonation attacks . . . . . . . . . . . . . . . . . . 37
6.2. Denial of Service attacks . . . . . . . . . . . . . . . . 37 6.2. Denial of Service attacks . . . . . . . . . . . . . . . . 38
6.2.1. Flooding Attacks . . . . . . . . . . . . . . . . . . . 37 6.2.1. Flooding Attacks . . . . . . . . . . . . . . . . . . . 38
6.2.2. Memory/Computational exhaustion DoS attacks . . . . . 38 6.2.2. Memory/Computational exhaustion DoS attacks . . . . . 39
6.3. Mixed deployment environment . . . . . . . . . . . . . . . 38 6.3. Mixed deployment environment . . . . . . . . . . . . . . . 39
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 40 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 41
8. Authors and Acknowledgments . . . . . . . . . . . . . . . . . 41 8. Authors and Acknowledgments . . . . . . . . . . . . . . . . . 42
9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 42 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 43
9.1. Normative references . . . . . . . . . . . . . . . . . . . 42 9.1. Normative references . . . . . . . . . . . . . . . . . . . 43
9.2. Informative references . . . . . . . . . . . . . . . . . . 42 9.2. Informative references . . . . . . . . . . . . . . . . . . 43
Appendix A. Changes from previous versions . . . . . . . . . . . 43 Appendix A. Changes from previous versions . . . . . . . . . . . 44
A.1. From nikander-hip-mm-00 to nikander-hip-mm-01 . . . . . . 43 A.1. From nikander-hip-mm-00 to nikander-hip-mm-01 . . . . . . 44
A.2. From nikander-hip-mm-01 to nikander-hip-mm-02 . . . . . . 43 A.2. From nikander-hip-mm-01 to nikander-hip-mm-02 . . . . . . 44
A.3. From -02 to draft-ietf-hip-mm-00 . . . . . . . . . . . . . 43 A.3. From -02 to draft-ietf-hip-mm-00 . . . . . . . . . . . . . 44
A.4. From draft-ietf-hip-mm-00 to -01 . . . . . . . . . . . . . 44 A.4. From draft-ietf-hip-mm-00 to -01 . . . . . . . . . . . . . 45
A.5. From draft-ietf-hip-mm-01 to -02 . . . . . . . . . . . . . 44 A.5. From draft-ietf-hip-mm-01 to -02 . . . . . . . . . . . . . 45
A.6. From draft-ietf-hip-mm-02 to -03 . . . . . . . . . . . . . 44 A.6. From draft-ietf-hip-mm-02 to -03 . . . . . . . . . . . . . 45
A.7. From draft-ietf-hip-mm-03 to -04 . . . . . . . . . . . . . 45 A.7. From draft-ietf-hip-mm-03 to -04 . . . . . . . . . . . . . 46
Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 46 A.8. From draft-ietf-hip-mm-04 to -05 . . . . . . . . . . . . . 46
Intellectual Property and Copyright Statements . . . . . . . . . . 47 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 47
Intellectual Property and Copyright Statements . . . . . . . . . . 48
1. Introduction and Scope 1. Introduction and Scope
The Host Identity Protocol [1] (HIP) supports an architecture that The Host Identity Protocol [1] (HIP) supports an architecture that
decouples the transport layer (TCP, UDP, etc.) from the decouples the transport layer (TCP, UDP, etc.) from the
internetworking layer (IPv4 and IPv6) by using public/private key internetworking layer (IPv4 and IPv6) by using public/private key
pairs, instead of IP addresses, as host identities. When a host uses pairs, instead of IP addresses, as host identities. When a host uses
HIP, the overlying protocol sublayers (e.g., transport layer sockets HIP, the overlying protocol sublayers (e.g., transport layer sockets
and ESP Security Associations) are instead bound to representations and ESP Security Associations) are instead bound to representations
of these host identities, and the IP addresses are only used for of these host identities, and the IP addresses are only used for
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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
address. The set of possible addresses is a subset of the set of address. The set of possible addresses is a subset of the set of
possible locators. possible locators.
Preferred locator. A locator on which a host prefers to receive data. Preferred locator. A locator on which a host prefers to receive
With respect to a given peer, a host always has one active data. With respect to a given peer, a host always has one active
Preferred locator, unless there are no active locators. By Preferred locator, unless there are no active locators. By
default, the locators used in the HIP base exchange are the default, the locators used in the HIP base exchange are the
Preferred locators. Preferred locators.
Credit Based Authorization. A host must verify a mobile or multi- Credit Based Authorization. A host must verify a mobile or multi-
homed peer's reachability at a new locator. Credit-Based homed peer's reachability at a new locator. Credit-Based
Authorization authorizes the peer to receive a certain amount of Authorization authorizes the peer to receive a certain amount of
data at the new locator before the result of such verification is data at the new locator before the result of such verification is
known. known.
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First, the peer must be notified of the address change using a HIP First, the peer must be notified of the address change using a HIP
UPDATE message. Second, each host must change its local bindings at UPDATE message. Second, each host must change its local bindings at
the HIP sublayer (new IP addresses). It may be that both the SPIs the HIP sublayer (new IP addresses). It may be that both the SPIs
and IP addresses are changed simultaneously in a single UPDATE; the and IP addresses are changed simultaneously in a single UPDATE; the
protocol described herein supports this. However, simultaneous protocol described herein supports this. However, simultaneous
movement of both hosts, notification of transport layer protocols of movement of both hosts, notification of transport layer protocols of
the path change, and procedures for possibly traversing middleboxes the path change, and procedures for possibly traversing middleboxes
are not covered by this document. are not covered by this document.
Finally, consider the case when a host is multihomed (has more than Finally, consider the case when a host is multihomed (has more than
one globally routable address) and makes these multiple addresses one globally routable address) and has multiple addresses available
available for use by the upper layer protocols, for fault tolerance. at the HIP layer as alternative locators, for fault tolerance.
Examples include the use of (possibly multiple) IPv4 and IPv6 Examples include the use of (possibly multiple) IPv4 and IPv6
addresses on the same interface, or the use of multiple interfaces addresses on the same interface, or the use of multiple interfaces
attached to different service providers. Such host multihoming attached to different service providers. Such host multihoming
generally necessitates that a separate ESP SA is maintained for each generally necessitates that a separate ESP SA is maintained for each
interface in order to prevent packets that arrive over different interface in order to prevent packets that arrive over different
paths from falling outside of the ESP replay protection window. paths from falling outside of the ESP anti-replay window [4].
Multihoming thus makes possible that the bindings shown on the right Multihoming thus makes possible that the bindings shown on the right
side of Figure 2 are one to many (in the outbound direction, one HIT side of Figure 2 are one to many (in the outbound direction, one HIT
pair to multiple SPIs, and possibly then to multiple IP addresses). pair to multiple SPIs, and possibly then to multiple IP addresses).
However, only one SPI and address pair can be used for any given However, only one SPI and address pair can be used for any given
packet, so the job of the "MH" block depicted above is to dynamically packet, so the job of the "MH" block depicted above is to dynamically
manipulate these bindings. Beyond locally managing such multiple manipulate these bindings. Beyond locally managing such multiple
bindings, the peer-to-peer HIP signaling protocol needs to be bindings, the peer-to-peer HIP signaling protocol needs to be
flexible enough to define the desired mappings between HITs, SPIs, flexible enough to define the desired mappings between HITs, SPIs,
and addresses, and needs to ensure that UPDATE messages are sent and addresses, and needs to ensure that UPDATE messages are sent
along the right network paths so that any HIP-aware middleboxes can along the right network paths so that any HIP-aware middleboxes can
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3.1.1. Locator 3.1.1. Locator
This document defines a generalization of an address called a This document defines a generalization of an address called a
"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 violation of the ESP anti-replay with certain ESP SPIs, to avoid violation ESP anti-replay window.
window [4]. Addresses may also be affiliated with transport ports in Addresses may also be affiliated with transport ports in certain
certain tunneling scenarios. Locators may simply be traditional tunneling scenarios. Locators may simply be traditional network
network addresses. The format of the locators is defined in addresses. The format of the locators is defined in Section 4.
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
parameter. This UPDATE packet is acknowledged by the peer, and is parameter. This UPDATE packet is acknowledged by the peer. For
protected by retransmission. The peer can authenticate the contents reliability in the presence of packet loss, the UPDATE packet is
of the UPDATE packet based on the signature and keyed hash of the retransmitted as defined in the HIP protocol specification [2]. The
packet. peer can authenticate the contents of the UPDATE packet based on the
signature and keyed hash of the packet.
When using ESP Transport Format [6], the host may at the same time When using ESP Transport Format [6], the host may at the same time
decide to rekey its security association and possibly generate a new decide to rekey its security association and possibly generate a new
Diffie-Hellman key; all of these actions are triggered by including Diffie-Hellman key; all of these actions are triggered by including
additional parameters in the UPDATE packet, as defined in the base additional parameters in the UPDATE packet, as defined in the base
protocol specification [2] and ESP extension [6]. protocol specification [2] and ESP extension [6].
When using ESP (and possibly other transport modes in the future), When using ESP (and possibly other transport modes in the future),
the host is able to receive packets that are protected using a HIP the host is able to receive packets that are protected using a HIP
created ESP SA from any address. Thus, a host can change its IP created ESP SA from any address. Thus, a host can change its IP
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Figure 4: Readdress with mobile-initiated rekey Figure 4: Readdress with mobile-initiated rekey
3.2.3. Host multihoming 3.2.3. Host multihoming
A (mobile or stationary) host may sometimes have more than one A (mobile or stationary) host may sometimes have more than one
interface or global address. The host may notify the peer host of interface or global address. The host may notify the peer host of
the additional interface or address by using the LOCATOR parameter. the additional interface or address by using the LOCATOR parameter.
To avoid problems with the ESP anti-replay window, a host SHOULD use To avoid problems with the ESP anti-replay window, a host SHOULD use
a different SA for each interface or address used to receive packets a different SA for each interface or address used to receive packets
from the peer host. from the peer host, when multiple locator pairs are being used
simultaneously rather than sequentially.
When more than one locator is provided to the peer host, the host When more than one locator is provided to the peer host, the host
SHOULD indicate which locator is preferred. By default, the SHOULD indicate which locator is preferred (the locator on which the
addresses used in the base exchange are preferred until indicated host prefers to receive traffic). By default, the addresses used in
otherwise. the base exchange are preferred until indicated otherwise.
In the multihoming case, the sender may also have multiple valid
locators from which to source traffic. In practice, a HIP
association in a multihoming configuration may have both a preferred
peer locator and a preferred local locator, although rules for source
address selection should ultimately govern the selection of source
locator based on the destination locator.
Although the protocol may allow for configurations in which there is Although the protocol may allow for configurations in which there is
an asymmetric number of SAs between the hosts (e.g., one host has two an asymmetric number of SAs between the hosts (e.g., one host has two
interfaces and two inbound SAs, while the peer has one interface and interfaces and two inbound SAs, while the peer has one interface and
one inbound SA), it is RECOMMENDED that inbound and outbound SAs be one inbound SA), it is RECOMMENDED that inbound and outbound SAs be
created pairwise between hosts. When an ESP_INFO arrives to rekey a created pairwise between hosts. When an ESP_INFO arrives to rekey a
particular outbound SA, the corresponding inbound SA should be also particular outbound SA, the corresponding inbound SA should be also
rekeyed at that time. Although asymmetric SA configurations might be rekeyed at that time. Although asymmetric SA configurations might be
experimented with, their usage may constrain interoperability at this experimented with, their usage may constrain interoperability at this
time. However, it is recommended that implementations attempt to time. However, it is recommended that implementations attempt to
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Credit-Based Authorization (CBA) allows a host to securely use a new Credit-Based Authorization (CBA) allows a host to securely use a new
locator even though the peer's reachability at the address embedded locator even though the peer's reachability at the address embedded
in the locator has not yet been verified. This is accomplished based in the locator has not yet been verified. This is accomplished based
on the following three hypotheses: on the following three hypotheses:
1. A flooding attacker typically seeks to somehow multiply the 1. A flooding attacker typically seeks to somehow multiply the
packets it generates for the purpose of its attack because packets it generates for the purpose of its attack because
bandwidth is an ample resource for many victims. bandwidth is an ample resource for many victims.
2. An attacker can always cause unamplified flooding by sending 2. An attacker can often cause unamplified flooding by sending
packets to its victim directly. packets to its victim, either by directly addressing the victim
in the packets, or by guiding the packets along a specific path
by means of an IPv6 Routing header, if Routing headers are not
filtered by firewalls.
3. Consequently, the additional effort required to set up a 3. Consequently, the additional effort required to set up a
redirection-based flooding attack (without CBA and return redirection-based flooding attack (without CBA and return
routability checks) would pay off for the attacker only if routability checks) would pay off for the attacker only if
amplification could be obtained this way. amplification could be obtained this way.
On this basis, rather than eliminating malicious packet redirection On this basis, rather than eliminating malicious packet redirection
in the first place, Credit-Based Authorization prevents in the first place, Credit-Based Authorization prevents
amplifications. This is accomplished by limiting the data a host can amplifications. This is accomplished by limiting the data a host can
send to an unverified address of a peer by the data recently received send to an unverified address of a peer by the data recently received
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shown in Figure 9 are the results of credit aging (Section 5.6.2), a shown in Figure 9 are the results of credit aging (Section 5.6.2), a
mechanism used to dampen possible time-shifting attacks. mechanism used to dampen possible time-shifting attacks.
+-------+ +-------+ +-------+ +-------+
| A | | B | | A | | B |
+-------+ +-------+ +-------+ +-------+
| | | |
address |------------------------------->| credit += size(packet) address |------------------------------->| credit += size(packet)
ACTIVE | | ACTIVE | |
|------------------------------->| credit += size(packet) |------------------------------->| credit += size(packet)
|<-------------------------------| don't change credit |<-------------------------------| do not change credit
| | | |
+ address change | + address change |
+ address verification starts | + address verification starts |
address |<-------------------------------| credit -= size(packet) address |<-------------------------------| credit -= size(packet)
UNVERIFIED |------------------------------->| credit += size(packet) UNVERIFIED |------------------------------->| credit += size(packet)
|<-------------------------------| credit -= size(packet) |<-------------------------------| credit -= size(packet)
| | | |
|<-------------------------------| credit -= size(packet) |<-------------------------------| credit -= size(packet)
| X credit < size(packet) | X credit < size(packet)
| | => do not send packet! | | => do not send packet!
+ address verification concludes | + address verification concludes |
address | | address | |
ACTIVE |<-------------------------------| don't change credit ACTIVE |<-------------------------------| do not change credit
| | | |
Figure 9: Readdressing Scenario Figure 9: Readdressing Scenario
3.3.3. Preferred locator 3.3.3. Preferred locator
When a host has multiple locators, the peer host must decide upon When a host has multiple locators, the peer host must decide upon
which to use for outbound packets. It may be that a host would which to use for outbound packets. It may be that a host would
prefer to receive data on a particular inbound interface. HIP allows prefer to receive data on a particular inbound interface. HIP allows
a particular locator to be designated as a Preferred locator, and a particular locator to be designated as a Preferred locator, and
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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 lifetime (seconds), o lifetime (seconds),
o status (UNVERIFIED, ACTIVE, DEPRECATED). o status (UNVERIFIED, ACTIVE, DEPRECATED),
o the Traffic Type scope of the locator, and
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 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:
UNVERIFIED to ACTIVE The reachability procedure completes UNVERIFIED to ACTIVE The reachability procedure completes
successfully. successfully.
UNVERIFIED to DEPRECATED The locator lifetime expires while it is UNVERIFIED to DEPRECATED The locator lifetime expires while the
UNVERIFIED. locator is UNVERIFIED.
ACTIVE to DEPRECATED The locator lifetime expires while it is ACTIVE. ACTIVE to DEPRECATED The locator lifetime expires while the locator
is ACTIVE.
ACTIVE to UNVERIFIED There has been no traffic on the address for ACTIVE to UNVERIFIED There has been no traffic on the address for
some time, and the local policy mandates that the address some time, and the local policy mandates that the address
reachability must be verified again before starting to use it reachability must be verified again before starting to use it
again. again.
DEPRECATED to UNVERIFIED The host receives a new lifetime for the DEPRECATED to UNVERIFIED The host receives a new lifetime for the
locator. locator.
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 a locator is preferred or not is not
necessarily the same as the value of the Preferred bit in the Locator
sub-parameter received from the peer. Peers may recommend certain
locators to be preferred, but the decision on whether to actually use
a locator as a preferred locator is a local decision possibly
influenced by local policy.
5.2. Sending LOCATORs 5.2. Sending LOCATORs
The decision of when to send LOCATORs is basically a local policy The decision of when to send LOCATORs is basically a local policy
issue. However, it is RECOMMENDED that a host sends a LOCATOR issue. However, it is RECOMMENDED that a host sends a LOCATOR
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. Rapidly sending LOCATORs that force the
peer to change the preferred address SHOULD be avoided. 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 interaction requires sending the same LOCATOR in separate UPDATEs on
on different paths. Since each SPI is associated with a different 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 is to
provide connectivity between the communicating hosts. In most cases, provide connectivity between the communicating hosts. In most cases,
tunnels or virtual interfaces such as IPsec tunnel interfaces or tunnels or virtual interfaces such as IPsec tunnel interfaces or
Mobile IP home addresses provide sub-optimal connectivity. 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. Hosts MUST NOT addresses of virtual interfaces may be appropriate.
announce broadcast or multicast addresses in LOCATORs. The
announcement of link-local addresses is a policy decision; such Hosts MUST NOT announce broadcast or multicast addresses in LOCATORs.
addresses used as Preferred locators will create reachability Link-local addresses MAY be announced to peers that are known to be
problems when the host moves to another link. neighbors on the same link, such as when the IP destination address
of a peer is also link-local. The announcement of link-local
addresses in this case is a policy decision; link-local addresses
used as Preferred locators will create reachability problems when the
host moves to another link. In any case, link-local addresses MUST
NOT be announced to a peer unless that peer is 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 parameter that serves as a complete
representation of the addresses and affiliated SPIs intended for representation of the addresses and affiliated SPIs intended for
active use. We now describe a few cases introduced in Section 3.2. active use. We now describe a few cases introduced in Section 3.2.
We assume that the Traffic Type for each locator is set to "0" (other We assume that the Traffic Type for each locator is set to "0" (other
values for Traffic Type may be specified in documents that separate values for Traffic Type may be specified in documents that separate
HIP control plane from data plane traffic). Other mobility and HIP control plane from data plane traffic). Other mobility and
multihoming cases are possible but are left for further multihoming cases are possible but are left for further
experimentation. 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 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 contains a single Locator with a "Locator Type" of "1";
the SPI must match that of the ESP_INFO. The Preferred bit 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.
and is protected by retransmission. The UPDATE should be sent to This packet is retransmitted as defined in the HIP protocol
the peer's preferred IP address with an IP source address specification [2]. The UPDATE should be sent to the peer's
corresponding to the address in the LOCATOR parameter. preferred IP address with an IP source address corresponding to
the address in the LOCATOR 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 parameter (with a single address). The ESP_INFO
contains the current value of the SPI in the "Old SPI" and the contains the current value of the SPI in the "Old SPI" and the
new value of the SPI in the "New SPI", and a "Keymat Index" as new value of the SPI in the "New SPI", and a "Keymat Index" as
selected by local policy. Optionally, the host may choose to selected by local policy. Optionally, the host may choose to
initiate a Diffie Hellman rekey by including a DIFFIE_HELLMAN initiate a Diffie Hellman rekey by including a DIFFIE_HELLMAN
parameter. The LOCATOR contains a single Locator with "Locator parameter. The LOCATOR contains a single Locator with "Locator
Type" of "1"; the SPI must match that of the "New SPI" in the Type" of "1"; the SPI must match that of the "New SPI" in the
skipping to change at page 30, line 41 skipping to change at page 31, line 12
LOCATOR parameter have either a state of UNVERIFIED or ACTIVE, and LOCATOR parameter have either a state of UNVERIFIED or ACTIVE, and
any old addresses on the old SA not listed in the LOCATOR parameter any old addresses on the old SA not listed in the LOCATOR parameter
have a state of DEPRECATED. 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 parameter
contains a new Preferred locator, the host SHOULD initiate a change contains a new Preferred locator, the host SHOULD initiate a change
of the Preferred locator. This requires that the host first verifies of the Preferred locator. This requires that the host first verifies
reachability of the associated address, and only then changes the reachability of the associated address, and only then changes the
Preferred locator. See Section 5.5. Preferred locator. See Section 5.5.
If a host receives a locator with an unsupported Locator Type, when
such locator is also declared to be the Preferred locator for the
peer, the host SHOULD send a NOTIFY error with a Notify Message Type
of LOCATOR_TYPE_UNSUPPORTED, with the Notification Data field
containing the locator(s) that the receiver failed to process.
Otherwise, a host MAY send a NOTIFY error if a (non-preferred)
locator with an unsupported Locator Type is received in a LOCATOR
parameter.
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
skipping to change at page 41, line 5 skipping to change at page 41, line 11
address via an UPDATE. Other possibilities exist but a simple address via an UPDATE. Other possibilities exist but a simple
solution is to prevent use of HIP address check information to solution is to prevent use of HIP address check information to
influence non-HIP sessions. 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 parameter for the Host Identity
Protocol [2]. This parameter is defined in Section 4 with a Type of Protocol [2]. This parameter is defined in Section 4 with a Type of
193. 193.
This document also defines a LOCATOR_TYPE_UNSUPPORTED Notify Message
Type as defined in the Host Identity Protocol specification [2].
This parameter is defined in Section 5.3 with a Value of 46.
8. Authors and Acknowledgments 8. Authors and Acknowledgments
Pekka Nikander originated this Internet Draft. Tom Henderson, Jari Pekka Nikander originated this Internet Draft. Tom Henderson, Jari
Arkko, Greg Perkins, and Christian Vogt have each contributed Arkko, Greg Perkins, and Christian Vogt have each contributed
sections to this draft. sections to this draft.
The authors thank Miika Komu, Mika Kousa, Jeff Ahrenholz, and Jan The authors thank Miika Komu, Mika Kousa, Jeff Ahrenholz, and Jan
Melen for many improvements to the draft. Melen for many improvements to the draft.
9. References 9. References
9.1. Normative references 9.1. Normative references
[1] Moskowitz, R. and P. Nikander, "Host Identity Protocol [1] Moskowitz, R. and P. Nikander, "Host Identity Protocol
Architecture", RFC 4423, August 2005. Architecture", RFC 4423, August 2005.
[2] Moskowitz, R., "Host Identity Protocol", draft-ietf-hip-base-05 [2] Moskowitz, R., "Host Identity Protocol", draft-ietf-hip-base-07
(work in progress), March 2006. (work in progress), February 2007.
[3] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP) [3] Laganier, J. and L. Eggert, "Host Identity Protocol (HIP)
Rendezvous Extension", draft-ietf-hip-rvs-04 (work in progress), Rendezvous Extension", draft-ietf-hip-rvs-05 (work in
October 2005. progress), June 2006.
[4] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303, [4] Kent, S., "IP Encapsulating Security Payload (ESP)", RFC 4303,
December 2005. December 2005.
[5] Draves, R., "Default Address Selection for Internet Protocol [5] Draves, R., "Default Address Selection for Internet Protocol
version 6 (IPv6)", RFC 3484, February 2003. version 6 (IPv6)", RFC 3484, February 2003.
[6] Jokela, P., "Using ESP transport format with HIP", [6] Jokela, P., "Using ESP transport format with HIP",
draft-ietf-hip-esp-02 (work in progress), March 2006. draft-ietf-hip-esp-05 (work in progress), February 2007.
[7] Bradner, S., "Key words for use in RFCs to Indicate Requirement [7] Bradner, S., "Key words for use in RFCs to Indicate Requirement
Levels", BCP 14, RFC 2119, March 1997. Levels", BCP 14, RFC 2119, March 1997.
[8] Hinden, R. and S. Deering, "IP Version 6 Addressing [8] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 2373, July 1998. Architecture", RFC 2373, July 1998.
9.2. Informative references 9.2. Informative references
[9] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E. [9] Nikander, P., Arkko, J., Aura, T., Montenegro, G., and E.
skipping to change at page 46, line 5 skipping to change at page 46, line 39
Rewrote Sections 5.2 and 5.3 on sending and receiving LOCATOR, to Rewrote Sections 5.2 and 5.3 on sending and receiving LOCATOR, to
more explicitly cover the scenario scope of this document. more explicitly cover the scenario scope of this document.
Removed unwritten "Policy Considerations" section Removed unwritten "Policy Considerations" section
A.7. From draft-ietf-hip-mm-03 to -04 A.7. From draft-ietf-hip-mm-03 to -04
Responded to numerous WGLC comments and corrections from Miika Komu Responded to numerous WGLC comments and corrections from Miika Komu
(responses on the HIP mailing list) (responses on the HIP mailing list)
A.8. From draft-ietf-hip-mm-04 to -05
Responded to Jeffrey Hutzelman comments as part of IETF secdir
review, and discussion with Christian Vogt. This includes clarifying
how UPDATE retransmissions are handled, a clarification on Credit-
Based Authorization flooding attacks, how to handle unsupported
Locator Type values, and the announcement of link-local addresses.
Handled several editorial comments from Marcelo Bagnulo Braun
regarding the host multihoming procedures.
New use-case section by Marcelo Bagnulo Braun to clarify the
multihoming case of sequential address usage (to be provided)
Author's Address Author's Address
Tom Henderson Tom Henderson
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
Intellectual Property Statement Full Copyright Statement
Copyright (C) The IETF Trust (2007).
This document is subject to the rights, licenses and restrictions
contained in BCP 78, and except as set forth therein, the authors
retain all their rights.
This document and the information contained herein are provided on an
"AS IS" basis and THE CONTRIBUTOR, THE ORGANIZATION HE/SHE REPRESENTS
OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY, THE IETF TRUST AND
THE INTERNET ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS
OR IMPLIED, INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF
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The IETF takes no position regarding the validity or scope of any The IETF takes no position regarding the validity or scope of any
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skipping to change at page 47, line 29 skipping to change at page 48, line 45
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OR IS SPONSORED BY (IF ANY), THE INTERNET SOCIETY AND THE INTERNET
ENGINEERING TASK FORCE DISCLAIM ALL WARRANTIES, EXPRESS OR IMPLIED,
INCLUDING BUT NOT LIMITED TO ANY WARRANTY THAT THE USE OF THE
INFORMATION HEREIN WILL NOT INFRINGE ANY RIGHTS OR ANY IMPLIED
WARRANTIES OF MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE.
Copyright Statement
Copyright (C) The Internet Society (2006). This document is subject
to the rights, licenses and restrictions contained in BCP 78, and
except as set forth therein, the authors retain all their rights.
Acknowledgment Acknowledgment
Funding for the RFC Editor function is currently provided by the Funding for the RFC Editor function is provided by the IETF
Internet Society. Administrative Support Activity (IASA).
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