< draft-ietf-mext-nemo-pd-06.txt   draft-ietf-mext-nemo-pd-07.txt >
Mobility Extensions for IPv6 R. Droms Mobility Extensions for IPv6 R. Droms
(MEXT) P. Thubert (MEXT) P. Thubert
Internet-Draft Cisco Internet-Draft Cisco
Intended status: Standards Track F. Dupont Intended status: Standards Track F. Dupont
Expires: February 23, 2011 ISC Expires: June 23, 2011 ISC
W. Haddad W. Haddad
Ericsson Ericsson
CJ. Bernardos CJ. Bernardos
UC3M UC3M
August 22, 2010 December 20, 2010
DHCPv6 Prefix Delegation for NEMO DHCPv6 Prefix Delegation for NEMO
draft-ietf-mext-nemo-pd-06 draft-ietf-mext-nemo-pd-07
Abstract Abstract
One aspect of network mobility support is the assignment of a prefix One aspect of network mobility support is the assignment of a prefix
or prefixes to a Mobile Router (MR) for use on the links in the NEMO. or prefixes to a mobile router for use on the links in the mobile
DHCPv6 prefix delegation can be used for this configuration task. network. This document specifies how DHCPv6 prefix delegation can be
used for this configuration task. The mobile router plays the role
of requesting router, while the home agent assumes the role of
delegating router. When the mobile router is outside its home
network, the mobile router also assumes the role of DHCPv6 relay
agent, co-located with the requesting router function.
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.
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Internet-Drafts are draft documents valid for a maximum of six months Internet-Drafts are draft documents valid for a maximum of six months
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This Internet-Draft will expire on February 23, 2011. This Internet-Draft will expire on June 23, 2011.
Copyright Notice Copyright Notice
Copyright (c) 2010 IETF Trust and the persons identified as the Copyright (c) 2010 IETF Trust and the persons identified as the
document authors. All rights reserved. document authors. All rights reserved.
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skipping to change at page 2, line 14 skipping to change at page 2, line 20
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. DHCPv6 Prefix Delegation of Mobile Network Prefixes . . . . . 4 3. DHCPv6 Prefix Delegation of Mobile Network Prefixes . . . . . 4
3.1. Exchanging DHCPv6 messages when the MR is not at home . . 5 3.1. Exchanging DHCPv6 messages when the mobile router is
3.1.1. Relay agent configuration . . . . . . . . . . . . . . 6 not at home . . . . . . . . . . . . . . . . . . . . . . . 5
3.1.2. Transmission of DHCPv6 messages . . . . . . . . . . . 7 3.1.1. Relay agent configuration . . . . . . . . . . . . . . 7
3.1.3. Receipt of DHCPv6 messages . . . . . . . . . . . . . . 7 3.1.2. Transmission of DHCPv6 messages . . . . . . . . . . . 8
3.2. Exchanging DHCPv6 messages when MR is at home . . . . . . 7 3.1.3. Receipt of DHCPv6 messages . . . . . . . . . . . . . . 8
3.3. Selecting an HA that provides DHCPv6PD . . . . . . . . . . 8 3.2. Exchanging DHCPv6 messages when the mobile router is
3.4. Minimizing DHCPv6PD messages . . . . . . . . . . . . . . . 9 at home . . . . . . . . . . . . . . . . . . . . . . . . . 8
3.5. Other DHCPv6 functions . . . . . . . . . . . . . . . . . . 9 3.3. Selecting a home agent that provides DHCPv6PD . . . . . . 9
4. Security Considerations . . . . . . . . . . . . . . . . . . . 9 3.4. Minimizing DHCPv6PD messages . . . . . . . . . . . . . . . 10
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 11 3.5. Other DHCPv6 functions . . . . . . . . . . . . . . . . . . 10
6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 11 4. Security Considerations . . . . . . . . . . . . . . . . . . . 10
7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 11 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 12
7.1. Revision -00 . . . . . . . . . . . . . . . . . . . . . . . 11 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 12
7.2. Revision -01 . . . . . . . . . . . . . . . . . . . . . . . 11 7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 12
7.3. Revision -02 . . . . . . . . . . . . . . . . . . . . . . . 11 7.1. Revision -00 . . . . . . . . . . . . . . . . . . . . . . . 12
7.4. Revision -04 . . . . . . . . . . . . . . . . . . . . . . . 12 7.2. Revision -01 . . . . . . . . . . . . . . . . . . . . . . . 12
7.5. Revision -05 . . . . . . . . . . . . . . . . . . . . . . . 12 7.3. Revision -02 . . . . . . . . . . . . . . . . . . . . . . . 13
7.6. Revision -06 . . . . . . . . . . . . . . . . . . . . . . . 12 7.4. Revision -04 . . . . . . . . . . . . . . . . . . . . . . . 13
8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 12 7.5. Revision -05 . . . . . . . . . . . . . . . . . . . . . . . 13
8.1. Normative References . . . . . . . . . . . . . . . . . . . 12 7.6. Revision -06 . . . . . . . . . . . . . . . . . . . . . . . 14
8.2. Informative References . . . . . . . . . . . . . . . . . . 13 7.7. Revision -07 . . . . . . . . . . . . . . . . . . . . . . . 14
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 13 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 14
8.1. Normative References . . . . . . . . . . . . . . . . . . . 14
8.2. Informative References . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 15
1. Introduction 1. Introduction
One aspect of network mobility support is the assignment of a prefix One aspect of network mobility support is the assignment of a prefix
or prefixes to a Mobile Router for use on the links in the NEMO. or prefixes to a Mobile Router for use on the links in the NEMO.
DHCPv6 prefix delegation [RFC3633] (DHCPv6PD) can be used for this DHCPv6 prefix delegation (DHCPv6PD) [RFC3633] can be used for this
configuration task. configuration task.
The model of operation of DHCPv6PD for prefix delegation is as
follows [RFC3633]. A delegating router is provided IPv6 prefixes to
be delegated to requesting routers. A requesting router requests
prefix(es) from the delegating router. The delegating router chooses
prefix(es) for delegation, and responds with prefix(es) to the
requesting router. The requesting router is then responsible for the
delegated prefix(es). Note that DHCPv6 options for prefix delegation
defined in [RFC3633] have been defined for general use across
routers, and not only for mobile routers running the NEMO Basic
Support protocol [RFC3963].
To use DHCPv6PD as prefix assignment mechanism in mobile networks,
when the mobile router is located at home the home agent assumes the
role of the delegating router and the mobile router assumes the role
of the requesting router. However, when the mobile router is away
from home, in addition to the roles when the mobile router is located
at home, the mobile router also assumes the role of a DHCPv6 relay
agent co-located with the requesting router function.
The DHCPv6PD server running at the home agent is provisioned with
prefixes to be assigned using any of the prefix assignment mechanisms
described in the DHCPv6PD specification [RFC3633].
2. Terminology 2. Terminology
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 RFC2119 [RFC2119]. document are to be interpreted as described in RFC2119 [RFC2119].
The following terms used in this document are defined in the IPv6 The following terms used in this document are defined in the IPv6
Addressing Architecture document [RFC4291]: Addressing Architecture document [RFC4291]:
Link-Local Unicast address Link-Local Unicast address
Link-Local Scope Multicast address Link-Local Scope Multicast address
The following terms used in this document are defined in the Mobile The following terms used in this document are defined in the Mobile
IPv6 specification [I-D.ietf-mext-rfc3775bis]: IPv6 specification [I-D.ietf-mext-rfc3775bis]:
Home Agent (HA) Home Agent (HA)
Home Link Home Link
Home Address (HoA)
Care-of Address (CoA)
Binding Update (BU)
Binding Acknowledgement (BA)
The following terms used in this document are defined in the Mobile The following terms used in this document are defined in the Mobile
Network terminology document [RFC4885]: Network terminology document [RFC4885]:
Mobile Router (MR) Mobile Router (MR)
Mobile Network (NEMO) Mobile Network (NEMO)
Mobile Network Prefix (MNP) Mobile Network Prefix (MNP)
The following terms used in this document are defined in the DHCPv6 The following terms used in this document are defined in the DHCPv6
[RFC3315] and DHCPv6 prefix delegation [RFC3633] specifications: [RFC3315] and DHCPv6 prefix delegation [RFC3633] specifications:
Delegating Router (DR; acts as a DHCPv6 server) Delegating Router (DR; acts as a DHCPv6 server)
Requesting Router (RR; acts as a DHCPv6 client) Requesting Router (RR; acts as a DHCPv6 client)
DHCPv6 Relay Agent (DRA) DHCPv6 Relay Agent (DRA)
The following acronym is used in this document: The following acronym is used in this document:
DHCPv6PD: DHCPv6 Prefix Delegation DHCPv6PD: DHCPv6 Prefix Delegation
3. DHCPv6 Prefix Delegation of Mobile Network Prefixes 3. DHCPv6 Prefix Delegation of Mobile Network Prefixes
The NEMO Basic Support protocol [RFC3963] extends the Mobile IPv6 The NEMO Basic Support protocol [RFC3963] extends the Mobile IPv6
protocol [I-D.ietf-mext-rfc3775bis] to enable network mobility. In protocol [I-D.ietf-mext-rfc3775bis] to enable network mobility. With
this extension, an MR uses the Mobile IPv6 protocol to establish and the NEMO Basic Support protocol a mobile router uses Mobile IPv6 to
maintain a session with its HA, and uses bidirectional tunneling establish and maintain a session with its home agent, and uses
between the MR and HA to provide a path through which nodes attached bidirectional tunneling between the mobile router and the home agent
to links in the NEMO can maintain connectivity with nodes not in the to provide a path through which nodes attached to links in the mobile
NEMO. network can maintain connectivity with nodes not in the NEMO.
The requirements for NEMO [RFC4885] include the ability of the MR to The requirements for Network Mobility [RFC4885] include the ability
receive delegated prefixes that can then be assigned to links in the of the mobile router to receive delegated prefixes that can then be
NEMO. DHCPv6PD can be used to meet this requirement for prefix assigned to links in the mobile network. DHCPv6PD can be used to
delegation. meet this requirement for prefix delegation.
To use DHCPv6PD for NEMOs, the HA assumes the role of the DR, and the To use DHCPv6PD for mobile networks, when the mobile router is
MR assumes the role of the RR when located at home, and the role of a located at home the home agent assumes the role of the delegating
DRA co-located with the RR function, when the MR is away from home. router and the mobile router assumes the role of the requesting
router. However, when the mobile router is away from home, in
addition to the roles when the mobile router is located at home, the
mobile router also assumes the role of a DHCPv6 relay agent co-
located with the requesting router function.
When the MR is not at home, the HA and MR exchange DHCPv6PD protocol When the mobile router is not at home, the home agent and the mobile
messages as specified in RFC3775bis. This means that messages sent router exchange DHCPv6PD protocol messages as specified in
by the MR include the Home Address destination option and messages [I-D.ietf-mext-rfc3775bis]. This means that the messages sent by the
sent by the HA make use of a Routing Header type 2. See Figure 1 for mobile router MUST include the Home Address destination option and
the deployment topologies when the MR is at home and when it is messages sent by the home agent MUST make use of a Routing Header
visiting a foreign network. type 2. See Figure 1 for the deployment topologies when the MR is at
home and when it is visiting a foreign network.
------ ------ ------ ------
| MR |----------------| HA | | MR |----------------| HA |
|(RR)| (home network) |(DR)| |(RR)| (home network) |(DR)|
------ ------ ------ ------
------- /-----------\ ------ ------- /-----------\ ------
| MR |----| Internet |-----| HA | | MR |----| Internet |-----| HA |
|(RR) | \-----------/ |(DR)| |(RR) | \-----------/ |(DR)|
|(DRA)| ------ |(DRA)| ------
------- -------
(visited network) (visited network)
Figure 1: Deployment topologies of the use of DHCPv6PD for delegation Figure 1: Deployment topologies of the use of DHCPv6PD for delegation
of MNPs of Mobile Network Prefixes
The DHCPv6PD server is provisioned with prefixes to be assigned using The DHCPv6PD server is provisioned with prefixes to be assigned using
any of the prefix assignment mechanisms described in the DHCPv6PD any of the prefix assignment mechanisms described in the DHCPv6PD
specifications. Other updates to the HA data structures required as specifications. Other updates to the home agent data structures
a side effect of prefix delegation are specified by the particular required as a side effect of prefix delegation are specified by the
network mobility protocol. For example, in the case of Basic Network particular network mobility protocol. For example, in the case of
Mobility Support [RFC3963], the HA would add an entry in its binding NEMO Basic Network Mobility Support [RFC3963], the HA would add an
cache registering the delegated prefix to the MR to which the prefix entry in its binding cache registering the delegated prefix to the
was delegated. mobile router to which the prefix was delegated.
3.1. Exchanging DHCPv6 messages when the MR is not at home 3.1. Exchanging DHCPv6 messages when the mobile router is not at home
The case when the MR is away from home is described in this section. The case when the mobile router is away from home is described in
Section 3.2 describes the protocol operation for the case when the MR this section. Section 3.2 describes the protocol operation for the
is attached to its home link. case when the mobile router is attached to its home link.
The MR MUST register at the HA (i.e. by sending a Binding Update to The mobile router MUST register at the home agent (i.e., by sending a
the HA) before initiating a DHCPv6 message exchange for prefix Binding Update to the home agent) before initiating a DHCPv6 message
delegation. Since the MR may not have yet requested any prefixes, exchange for prefix delegation. The mobile router MUST use implicit
implicit BU signaling MUST be used. While using the NEMO Basic BU signaling, since the mobile router may not have yet requested any
Support protocol with DHCPv6PD, implicit BU signaling is the default prefixes.
mode of operation.
If the MR does not have any active delegated prefixes (with unexpired If the mobile router does not have any active delegated prefixes
leases), the MR initiates a DHCPv6 message exchange with a DHCPv6 (with unexpired leases), the mobile router MUST initiate a DHCPv6
Solicit message as described in section 17 of RFC 3315 and section message exchange with a DHCPv6 Solicit message as described in
11.1 of RFC 3633. The Delegating Router at the HA responds with an section 17 of [RFC3315] and section 11.1 of [RFC3633]. The
Advertise message. Then, the MR requests a set of prefixes by delegating router at the home agent responds with an Advertise
sending a Request message. The DR includes the delegated prefixes in message. Then, the mobile router MUST request a set of prefixes by
a Reply message. Note that in this case, the MR has previously sent sending a Request message. The delegating router includes the
a BU to the HA without knowing yet the set of prefixes that it can delegated prefixes in a Reply message. Note that in this case, the
use as MNPs. The HA, upon reception of the implicit BU from the MR, mobile router has previously sent a Binding Update to the home agent
selects (in case this was not pre-configured already) the prefixes without knowing yet the set of prefixes that it can use as mobile
that would then be delegated to the MR via DHCPv6PD. The HA, once network prefixes. The home agent, upon reception of the implicit
the DHCPv6 signaling has been completed, adds an entry in its binding Binding Update from the mobile router, MUST select (in case this was
cache including the delegated prefixes. not pre-configured already) the prefixes that would then be delegated
to the mobile router via DHCPv6PD. The home agent, once the DHCPv6
signaling has been completed, MUST add an entry in its binding cache
including the delegated prefixes.
In case the MR has one or more active delegated prefixes -- as for In case the mobile router has one or more active delegated prefixes
example if the MR reboots or the MNP(s) currently used by the is -- as for example if the mobile router reboots or the mobile network
about to expire -- the MR initiates a DHCPv6 message exchange with a prefix(es) currently used by the mobile router is about to expire --
DHCPv6 Rebind message as described in section 18.1.2 of RFC 3315 and the mobile router MUST initiate a DHCPv6 message exchange with a
section 12.1 of RFC 3633. DHCPv6 Rebind message as described in section 18.1.2 of [RFC3315] and
section 12.1 of [RFC3633].
A DHPCv6 relay agent function [RFC3315] is used at the MR. This A DHPCv6 relay agent function [RFC3315] MUST be used at the mobile
relay agent function is co-located in the MR with the DHCPv6 client router. This relay agent function is co-located in the mobile router
function (see Figure 2). The DHCPv6 signaling between the MR and the with the DHCPv6 client function (see Figure 2). The DHCPv6 signaling
HA are exchanged between the DHCPv6 relay agent in the MR and the between the mobile router and the home agent is exchanged between the
DHCPv6 server on the HA. DHCPv6 messages from the MR to the HA are DHCPv6 relay agent in the mobile router and the DHCPv6 server on the
unicast packets sent from the unicast HoA of the MR to the global home agent. DHCPv6 messages from the mobile router to the home agent
unicast address of the HA, and therefore the Home Address destination are unicast packets sent from the unicast home address of the mobile
option is used. DHCPv6 replies from the HA to the MR are sent using router to the global unicast address of the home agent, and therefore
the Routing Header type 2, as specified in RFC3775bis. The DHCPv6 the Home Address destination option MUST be used. DHCPv6 replies
client in the MR hands any outbound DHCPv6 messages to the co-located from the home agent to the mobile router MUST be sent using the
relay agent. Responses from the DHCPv6 server are delivered to the Routing Header type 2, as specified in [I-D.ietf-mext-rfc3775bis].
relay agent function in the MR, which extracts the encapsulated The DHCPv6 client in the mobile router MUST hand any outbound DHCPv6
message and delivers it to the DHCPv6 client in the MR. messages to the co-located relay agent. Responses from the DHCPv6
server are delivered to the relay agent function in the mobile
router, which MUST extract the encapsulated message and deliver it to
the DHCPv6 client in the mobile router.
----------------------------- -------- ----------------------------- --------
| MR | | HA | | MR | | HA |
| (RR) (DRA) | | (DR) | | (RR) (DRA) | | (DR) |
---------------------------- -------- ---------------------------- --------
| | Binding Update | | | Binding Update |
| |------------------------>| | |------------------------>|
| | (HoA, CoA) | | | (HoA, CoA) |
| | | | | |
| | Binding Ack | | | Binding Ack |
skipping to change at page 6, line 33 skipping to change at page 7, line 30
|<..................|<-=====================--| |<..................|<-=====================--|
| | | | | |
| DHCPv6 Request | DHCPv6 Request | | DHCPv6 Request | DHCPv6 Request |
|..................>|--=====================->| |..................>|--=====================->|
| | | | | |
| DHCPv6 Reply | DHCPv6 Reply | | DHCPv6 Reply | DHCPv6 Reply |
|<..................|<-=====================--| |<..................|<-=====================--|
| | (Mobile Network Prefix) | | | (Mobile Network Prefix) |
| | | | | |
Figure 2: Signaling sequence when the MR is not at home Figure 2: Signaling sequence when the mobile router is not at home
Note that an MR using DHCPv6PD to obtain the set of prefixes to be Note that a mobile router using DHCPv6PD to obtain the set of
used as MNPs cannot derive its HoA from an MNP (as the MR does not prefixes to be used as mobile network prefixes cannot derive its home
know them before registering to the HA). Therefore, the MR is address from one of its mobile network prefix(es) (as the mobile
assigned its HoA from the prefix on its Home Link. router does not know them before registering to the home agent).
Therefore, the mobile router MUST assign its home address from the
prefix on its Home Link.
3.1.1. Relay agent configuration 3.1.1. Relay agent configuration
The use of the relay agent function in the MR allows the MR to The use of the relay agent function in the mobile router allows the
unicast DHCPv6 messages to the DHCPv6 server. The relay agent MUST mobile router to unicast DHCPv6 messages to the DHCPv6 server. The
be configured with the address of the DHCPv6 server. For the relay agent MUST be configured with the address of the DHCPv6 server.
purposes of NEMO, the relay agent assumes that the HA for the MR For the purposes of this specification, the relay agent assumes that
hosts the DHCPv6 server. Therefore, the MR MUST configure the DHCPv6 the home agent for the mobile router hosts the DHCPv6 server.
relay agent to forward DHCPv6 messages to the HA. Therefore, the mobile router MUST configure the DHCPv6 relay agent to
forward DHCPv6 messages to the home agent.
The DHCPv6 specification supports in certain scenarios the use of
unicast between the client and the server. However its use presents
some difficulties, as the client has to first receive a Server
Unicast option (section 22.12 of [RFC3315]) from the server, which
means that a Solicit/Advertise message exchange is required in
advance. That signaling exchange would require the presence of a
relay agent on the mobile router, and therefore little gain would be
achieved in this case from the use of the Server Unicast option.
3.1.2. Transmission of DHCPv6 messages 3.1.2. Transmission of DHCPv6 messages
When the DHCPv6 client in the MR sends a message, it hands the When the DHCPv6 client in the mobile router sends a message, it MUST
message to the DHCPv6 relay agent in the MR. The way in which the hand the message to the DHCPv6 relay agent in the mobile router. The
message is passed to the DHCP relay agent is beyond the scope of this way in which the message is passed to the DHCP relay agent is beyond
document. The relay agent encapsulates the message from the client the scope of this document. The relay agent encapsulates the message
according to RFC 3315 in a Relay-forward message and sends the from the client according to [RFC3315] in a Relay-forward message and
resulting DHCPv6 message to the HA. The relay agent sets the fields sends the resulting DHCPv6 message to the home agent. The relay
in the Relay-forward message as follows: agent sets the fields in the Relay-forward message as follows:
msg-type RELAY-FORW msg-type RELAY-FORW
hop-count 1 hop-count 1
link-address The home address of the MR link-address The home address of the mobile router
peer-address A non-link-local address from the MR egress interface peer-address The home address of the mobile router
(e.g., home address) used to send packets between the
HA and the MR
options MUST include a "Relay Message option" [RFC3315]; MAY options MUST include a "Relay Message option" [RFC3315]; MAY
include other options added by the relay agent. include other options added by the relay agent.
3.1.3. Receipt of DHCPv6 messages 3.1.3. Receipt of DHCPv6 messages
Messages from the DHCPv6 server will be returned to the DHCPv6 relay Messages from the DHCPv6 server will be returned to the DHCPv6 relay
agent, with the message for the DHCPv6 client encapsulated in the agent, with the message for the DHCPv6 client encapsulated in the
Relay Message option [RFC3315] in a Relay-reply message. The relay Relay Message option [RFC3315] in a Relay-reply message. The relay
agent function extracts the message for the client from the Relay agent function MUST extract the message for the client from the Relay
Message option and hands the message to the DHCPv6 client in the MR. Message option and hand the message to the DHCPv6 client in the
The way in which the message is passed to the client is beyond the mobile router. The way in which the message is passed to the client
scope of this document. is beyond the scope of this document.
3.2. Exchanging DHCPv6 messages when MR is at home 3.2. Exchanging DHCPv6 messages when the mobile router is at home
When the MR is on its home link, the HA uses the home link to When the mobile router is on its home link, the home agent MUST use
exchange DHCPv6PD messages with the MR (Figure 3). In this case, the the home link to exchange DHCPv6PD messages with the mobile router
DHCPv6 co-located relay function is disabled. It is the (Figure 3). In this case, the DHCPv6 co-located relay function MUST
responsibility of the implementation to determine when the MR is on be disabled. It is the responsibility of the implementation to
its home link. The Home Link Detection mechanism is described in the determine when the mobile router is on its home link. The Home Link
section 11.5.2 of RFC3775bis. Detection mechanism is described in the section 11.5.2 of
[I-D.ietf-mext-rfc3775bis].
-------- -------- -------- --------
| MR | | HA | | MR | | HA |
| (RR) | | (DR) | | (RR) | | (DR) |
-------- -------- -------- --------
| | | |
| DHCPv6 Solicit | | DHCPv6 Solicit |
|------------------------>| |------------------------>|
| | | |
| DHCPv6 Advertise | | DHCPv6 Advertise |
|<------------------------| |<------------------------|
| | | |
| DHCPv6 Request | | DHCPv6 Request |
|------------------------>| |------------------------>|
| | | |
| DHCPv6 Reply | | DHCPv6 Reply |
|<------------------------| |<------------------------|
| (Mobile Network Prefix) | | (Mobile Network Prefix) |
| | | |
Figure 3: Signaling sequence for the case the HA is at home Figure 3: Signaling sequence for the case the home agent is at home
3.3. Selecting an HA that provides DHCPv6PD 3.3. Selecting a home agent that provides DHCPv6PD
Not all nodes that are willing to act as an HA are required to Not all nodes that are willing to act as a home agent are required to
provide DHCPv6PD. Therefore, when selecting an HA, an MR that provide DHCPv6PD. Therefore, when selecting a home agent, a mobile
requires DHCPv6PD service must identify an HA that will provide the router that requires DHCPv6PD service MUST identify a home agent that
service. The MR can determine if an HA provides DHCPv6PD by will provide the service. The mobile router can determine if a home
initiating a DHCPv6 message exchange (i.e. sending a Solicit message) agent provides DHCPv6PD by initiating a DHCPv6 message exchange
in which the MR requests delegated prefix(es). If the HA does not (i.e., sending a Solicit message) in which the mobile router requests
respond or responds but does not delegate any prefix(es) in its delegated prefix(es). If the home agent does not respond or responds
response, the MR assumes that the HA does not provide DHCPv6PD but does not delegate any prefix(es) in its response, the mobile
service. The MR continues to query all candidate HAs until it finds router assumes that the home agent does not provide DHCPv6PD service.
an HA that provides DHCPv6PD. Note that in this particular case and The mobile router continues to query all candidate home agents until
if the MR is away from home, the MR has to have already performed an it finds one that provides DHCPv6PD. Note that in this particular
MIPv6 registration with the HA it queries. case and if the mobile router is away from home, the mobile router
has to have already performed a Mobile IPv6 registration with the
home agent it queries.
Querying an HA to determine if it provides DHCPv6PD requires a small Querying a home agent to determine if it provides DHCPv6PD requires
modification to the operation of DHCPv6 as described in RFC 3315. different operational variables than those recommended by the DHCPv6
Under normal circumstances, a host will continue to send DHCPv6 specification. [RFC3315] recommends that under normal circumstances,
Solicit messages until it receives a response (see Section 17 of RFC a host will continue to send DHCPv6 Solicit messages until it
3315). However, an HA may choose not to respond to the Solicit receives a response (see Section 17 of [RFC3315]), i.e., the Maximum
messages from the MR because the HA does not provide DHCPv6. Retransmission Duration (MRD) and Maximum Retransmission Count (MRC)
Therefore, when querying an HA to determine if the HA provides are both set to zero. However, a home agent may not respond to the
DHCPv6PD service, the MR SHOULD discontinue sending Solicit messages Solicit messages from the mobile router because the home agent does
to the HA after sending 6 Solicit messages, and conclude that the HA not support DHCPv6 prefix delegation. Therefore, when querying a
will not provide DHCPv6PD service. Sending 6 queries provides enough home agent to determine if the home agent provides DHCPv6PD service,
reliability for scenarios in which the wireless connectivity is lost it is RECOMMENDED that MRD and MRC be set to non-zero values so that
for a short period after sending the first BU message. the mobile router discontinues sending Solicit messages to the home
agent after sending 6 Solicit messages, and conclude that the home
agent will not provide DHCPv6PD service. Sending 6 queries provides
enough reliability for scenarios in which the wireless connectivity
is lost for a short period after sending the first Binding Update
message.
It is recommended that the MR uses a sequential probing of the HAs It is RECOMMENDED that the mobile router uses a sequential probing of
for DHCPv6PD service. the home agents for DHCPv6PD service.
3.4. Minimizing DHCPv6PD messages 3.4. Minimizing DHCPv6PD messages
DHCPv6PD in a NEMO can be combined with the Rapid Commit option The use DHCPv6PD in a mobile network can be combined with the Rapid
[RFC3315] to provide DHCPv6 prefix delegation with a two message Commit option [RFC3315] to provide DHCPv6 prefix delegation with a
exchange between the mobile router and the DHCPv6PD DR. two message exchange between the mobile router and the DHCPv6PD
delegating router.
3.5. Other DHCPv6 functions 3.5. Other DHCPv6 functions
The DHCPv6 messages exchanged between the MR and the HA MAY also be The DHCPv6 messages exchanged between the mobile router and the home
used for other DHCPv6 functions in addition to DHCPv6PD. For agent MAY also be used for other DHCPv6 functions in addition to
example, the HA MAY assign global addresses to the MR and MAY pass DHCPv6PD. For example, the home agent MAY assign global addresses to
other configuration information such as a list of available DNS the mobile router and MAY pass other configuration information such
recursive name servers [RFC3646] to the MR using the same DHCPv6 as a list of available DNS recursive name servers [RFC3646] to the
messages as used for DHCPV6PD. mobile router using the same DHCPv6 messages as used for DHCPv6PD.
The HA MAY act as a DHCPv6 relay agent for Mobile Nodes while it acts The home agent MAY act as a DHCPv6 relay agent for mobile nodes while
as a DR for MRs. it acts as a delegating router for mobile routers.
4. Security Considerations 4. Security Considerations
This document describes the use of DHCPv6 for prefix delegation in This document describes the use of DHCPv6 for prefix delegation in
NEMO. In addition to the security considerations for DHCPv6 mobile networks. In addition to the security considerations for
described in the "Security Considerations" section of the DHCPv6 base DHCPv6 described in the "Security Considerations" section of the
specification [RFC3315] and the "Security Considerations" of the DHCPv6 base specification [RFC3315] and the "Security Considerations"
DHCPv6 Prefix Delegation specification [RFC3633], there are two of the DHCPv6 Prefix Delegation specification [RFC3633], there are
aspects that need to be considered. two aspects that need to be considered.
First, the NEMO Basic Support specification requires the HA to First, the NEMO Basic Support specification requires the home agent
prevent an MR from claiming MNPs belonging to another MR. Upon to prevent a mobile router from claiming mobile network prefixes
reception of an implicit BU from an MR, the HA MUST only add prefixes belonging to another mobile router. Upon reception of an implicit
into the MR's Binding Cache Entry if the MR has a valid DHCPv6 Prefix Binding Update from a mobile router, the home agent MUST only add
Delegation lease for said prefixes. If the MR does not have a valid prefixes into the mobile router's Binding Cache Entry if the mobile
DHCPv6 Prefix Delegation lease, the HA MUST NOT add any prefixes into router has a valid DHCPv6 Prefix Delegation lease for said prefixes.
the MR's Binding Cache Entry. Upon the MR obtaining a valid DHCPv6 If the mobile router does not have a valid DHCPv6 Prefix Delegation
Prefix Delegation lease for a given set of prefixes, the HA MUST add lease, the home agent MUST NOT add any prefixes into the mobile
these prefixes to the MR's Binding Cache Entry. This avoids the HA router's Binding Cache Entry. Upon the mobile router obtaining a
forwarding traffic addressed to prefixes that have not been yet valid DHCPv6 Prefix Delegation lease for a given set of prefixes, the
delegated to the MR. home agent MUST add these prefixes to the mobile router's Binding
Cache Entry. This avoids the home agent forwarding traffic addressed
to prefixes that have not been yet delegated to the mobile router.
The use of DHCPv6, as described in this document, requires message The use of DHCPv6, as described in this document, requires message
integrity protection and source authentication. When the MR is at integrity protection and source authentication. When the mobile
home, normal DHCPv6 operation is used between MR and HA and therefore router is at home, normal DHCPv6 operation is used between the mobile
this specification does not add any new security issue. While the MR router and the home agent and therefore this specification does not
is away from home, the IPsec security mechanism mandated by MIPv6 add any new security issue. While the mobile router is away from
home, the IPsec security mechanism mandated by Mobile IPv6 [RFC3776]
MUST be used to secure the DHCPv6 signaling. In the following, we MUST be used to secure the DHCPv6 signaling. In the following, we
describe the Security Policy Database (SPD) and Security Association describe the Security Policy Database (SPD) and Security Association
Database (SAD) entries necessary to protect the DHCPv6 signaling. We Database (SAD) entries necessary to protect the DHCPv6 signaling. We
use the same format than that used by of [RFC4877]. The SPD and SAD use the same format used by [RFC4877]. The SPD and SAD entries are
entries are only example configurations. A particular mobile router only example configurations. A particular mobile router
implementation and a home agent implementation could configure implementation and a home agent implementation could configure
different SPD and SAD entries as long as they provide the required different SPD and SAD entries as long as they provide the required
security of the DHCPv6 signaling messages. security of the DHCPv6 signaling messages.
For the examples described in this document, a mobile router with For the examples described in this document, a mobile router with
home address "home_address_1", and a home agent with address home address "home_address_1", and a home agent with address
"home_agent_1" are assumed. If the home address of the mobile router "home_agent_1" are assumed. If the home address of the mobile router
changes, the SPD and SAD entries need to be re-created or updated for changes, the SPD and SAD entries need to be re-created or updated for
the new home address. the new home address.
skipping to change at page 11, line 8 skipping to change at page 12, line 18
remote_address = home_address_1 & remote_address = home_address_1 &
proto = UDP & local_port = DHCP proto = UDP & local_port = DHCP
- SA1(IN, spi_a, home_agent_1, ESP, TRANSPORT): - SA1(IN, spi_a, home_agent_1, ESP, TRANSPORT):
local_address = home_address_1 & local_address = home_address_1 &
remote_address = home_agent_1 & remote_address = home_agent_1 &
proto = UDP & remote_port = DHCP proto = UDP & remote_port = DHCP
5. IANA Considerations 5. IANA Considerations
This document describes the use of DHCPv6 for prefix delegation in This document describes the use of DHCPv6 for prefix delegation in
NEMOs. It does not introduce any additional IANA considerations. mobile networks. It does not introduce any additional IANA
considerations.
6. Acknowledgments 6. Acknowledgments
The authors would like to thank people who have given valuable The authors would like to thank people who have given valuable
comments on the mailing list. Specific suggestions from Ryuji comments on the mailing list. Specific suggestions from Ryuji
Wakikawa, George Tsirtsis, Alexandru Petrescu, Vijay Devarapalli and Wakikawa, George Tsirtsis, Alexandru Petrescu, Vijay Devarapalli and
Marcelo Bagnulo were incorporated into this document. Marcelo Bagnulo were incorporated into this document.
The authors would like to thank Julien Laganier, Michaela Vanderveen The authors would like to thank Julien Laganier, Michaela Vanderveen
and Jean-Michel Combes for their review of previous versions of this and Jean-Michel Combes for their review of previous versions of this
skipping to change at page 12, line 33 skipping to change at page 13, line 45
Only implicit BU mode supported. Only implicit BU mode supported.
Only DHCPv6 relay agent in the MR co-located with the DHCPv6 client Only DHCPv6 relay agent in the MR co-located with the DHCPv6 client
function is supported as mode of operation when the MR is away from function is supported as mode of operation when the MR is away from
home. home.
Security considerations include now the issue of the HA enforcing Security considerations include now the issue of the HA enforcing
that the MR registers the prefixes that were delegated to it via that the MR registers the prefixes that were delegated to it via
DHCPv6PD. DHCPv6PD.
Since RFC3775bis specifies that MR and HA operate in RO mode when Since [I-D.ietf-mext-rfc3775bis] specifies that MR and HA operate in
sending traffic between them, the term tunnel has been removed. RO mode when sending traffic between them, the term tunnel has been
removed.
Some typos detected and corrected. Some typos detected and corrected.
7.6. Revision -06 7.6. Revision -06
Some nits fixed. Some nits fixed.
7.7. Revision -07
Fixes and clarifying text as suggested during IESG review.
8. References 8. References
8.1. Normative References 8.1. Normative References
[I-D.ietf-mext-rfc3775bis]
Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", draft-ietf-mext-rfc3775bis-10 (work in
progress), October 2010.
[RFC2119] Bradner, S., "Key words for use in RFCs to Indicate [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate
Requirement Levels", BCP 14, RFC 2119, March 1997. Requirement Levels", BCP 14, RFC 2119, March 1997.
[RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., [RFC3315] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C.,
and M. Carney, "Dynamic Host Configuration Protocol for and M. Carney, "Dynamic Host Configuration Protocol for
IPv6 (DHCPv6)", RFC 3315, July 2003. IPv6 (DHCPv6)", RFC 3315, July 2003.
[RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic [RFC3633] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic
Host Configuration Protocol (DHCP) version 6", RFC 3633, Host Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003. December 2003.
[RFC3646] Droms, R., "DNS Configuration options for Dynamic Host [RFC3646] Droms, R., "DNS Configuration options for Dynamic Host
Configuration Protocol for IPv6 (DHCPv6)", RFC 3646, Configuration Protocol for IPv6 (DHCPv6)", RFC 3646,
December 2003. December 2003.
[RFC3776] Arkko, J., Devarapalli, V., and F. Dupont, "Using IPsec to
Protect Mobile IPv6 Signaling Between Mobile Nodes and
Home Agents", RFC 3776, June 2004.
[RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P. [RFC3963] Devarapalli, V., Wakikawa, R., Petrescu, A., and P.
Thubert, "Network Mobility (NEMO) Basic Support Protocol", Thubert, "Network Mobility (NEMO) Basic Support Protocol",
RFC 3963, January 2005. RFC 3963, January 2005.
[RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing [RFC4291] Hinden, R. and S. Deering, "IP Version 6 Addressing
Architecture", RFC 4291, February 2006. Architecture", RFC 4291, February 2006.
[RFC4877] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with [RFC4877] Devarapalli, V. and F. Dupont, "Mobile IPv6 Operation with
IKEv2 and the Revised IPsec Architecture", RFC 4877, IKEv2 and the Revised IPsec Architecture", RFC 4877,
April 2007. April 2007.
8.2. Informative References 8.2. Informative References
[I-D.ietf-mext-rfc3775bis]
Perkins, C., Johnson, D., and J. Arkko, "Mobility Support
in IPv6", draft-ietf-mext-rfc3775bis-06 (work in
progress), July 2010.
[RFC4885] Ernst, T. and H-Y. Lach, "Network Mobility Support [RFC4885] Ernst, T. and H-Y. Lach, "Network Mobility Support
Terminology", RFC 4885, July 2007. Terminology", RFC 4885, July 2007.
Authors' Addresses Authors' Addresses
Ralph Droms Ralph Droms
Cisco Cisco
1414 Massachusetts Avenue 1414 Massachusetts Avenue
Boxborough, MA 01719 Boxborough, MA 01719
USA USA
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