draft-ietf-mext-nemo-pd-03.txt   draft-ietf-mext-nemo-pd-04.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: April 29, 2010 ISC Expires: September 9, 2010 ISC
W. Haddad W. Haddad
Ericsson Ericsson
October 26, 2009 CJ. Bernardos
UC3M
March 8, 2010
DHCPv6 Prefix Delegation for NEMO DHCPv6 Prefix Delegation for NEMO
draft-ietf-mext-nemo-pd-03 draft-ietf-mext-nemo-pd-04
Abstract
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
Mobile Network. DHCPv6 prefix delegation can be used for this
configuration task.
Status of this Memo Status of this Memo
This Internet-Draft is submitted to IETF in full conformance with the This Internet-Draft is submitted to IETF 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), its areas, and its working groups. Note that Task Force (IETF), its areas, and its working groups. Note that
other groups may also distribute working documents as Internet- other groups may also distribute working documents as Internet-
Drafts. Drafts.
skipping to change at page 1, line 36 skipping to change at page 1, line 45
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."
The list of current Internet-Drafts can be accessed at The list of current Internet-Drafts can be accessed at
http://www.ietf.org/ietf/1id-abstracts.txt. http://www.ietf.org/ietf/1id-abstracts.txt.
The list of Internet-Draft Shadow Directories can be accessed at The list of Internet-Draft Shadow Directories can be accessed at
http://www.ietf.org/shadow.html. http://www.ietf.org/shadow.html.
This Internet-Draft will expire on April 29, 2010. This Internet-Draft will expire on September 9, 2010.
Copyright Notice Copyright Notice
Copyright (c) 2009 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.
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 in effect on the date of Provisions Relating to IETF Documents
publication of this document (http://trustee.ietf.org/license-info). (http://trustee.ietf.org/license-info) in effect on the date of
Please review these documents carefully, as they describe your rights publication of this document. Please review these documents
and restrictions with respect to this document. carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must
Abstract include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as
One aspect of network mobility support is the assignment of a prefix described in the BSD License.
or prefixes to a Mobile Router (MR) for use on the links in the
Mobile Network. DHCPv6 prefix delegation can be used for this
configuration task.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Application of DHCPv6 prefix delegation to mobile networks 3. Application of DHCPv6 prefix delegation to mobile networks
for delegation of home prefixes . . . . . . . . . . . . . . . 4 for delegation of home prefixes . . . . . . . . . . . . . . . 4
3.1. When the MR uses DHCPv6 . . . . . . . . . . . . . . . . . 4 3.1. When the MR uses DHCPv6 . . . . . . . . . . . . . . . . . 5
3.2. Use of MR-HA tunnel for DHCPv6 messages . . . . . . . . . 5 3.2. Use of MR-HA tunnel for DHCPv6 messages . . . . . . . . . 6
3.3. DHCPv6 Relay Agent for transmission of DHCPv6 messages . . 5 3.3. DHCPv6 Relay Agent for transmission of DHCPv6 messages . . 7
3.3.1. Relay agent configuration . . . . . . . . . . . . . . 5 3.3.1. Relay agent configuration . . . . . . . . . . . . . . 8
3.3.2. Transmission of DHCPv6 messages . . . . . . . . . . . 6 3.3.2. Transmission of DHCPv6 messages . . . . . . . . . . . 9
3.3.3. Receipt of DHCPv6 messages . . . . . . . . . . . . . . 6 3.3.3. Receipt of DHCPv6 messages . . . . . . . . . . . . . . 9
3.4. Exchanging DHCPv6 messages when MR is at home . . . . . . 6 3.4. Exchanging DHCPv6 messages when MR is at home . . . . . . 9
3.5. Selecting an HA that provides DHCPv6PD . . . . . . . . . . 7 3.5. Selecting an HA that provides DHCPv6PD . . . . . . . . . . 10
3.6. Minimizing DHCPv6PD messages . . . . . . . . . . . . . . . 7 3.6. Minimizing DHCPv6PD messages . . . . . . . . . . . . . . . 10
3.7. Location of DHCPv6PD Delegating Router function . . . . . 7 3.7. Location of DHCPv6PD Delegating Router function . . . . . 10
3.8. Other DHCPv6 functions . . . . . . . . . . . . . . . . . . 8 3.8. Other DHCPv6 functions . . . . . . . . . . . . . . . . . . 12
4. Security Considerations . . . . . . . . . . . . . . . . . . . 8 4. Security Considerations . . . . . . . . . . . . . . . . . . . 12
5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 14
6. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 10 6. Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . 14
6.1. Revision -00 . . . . . . . . . . . . . . . . . . . . . . . 10 7. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . . 14
6.2. Revision -01 . . . . . . . . . . . . . . . . . . . . . . . 10 7.1. Revision -00 . . . . . . . . . . . . . . . . . . . . . . . 14
6.3. Revision -02 . . . . . . . . . . . . . . . . . . . . . . . 11 7.2. Revision -01 . . . . . . . . . . . . . . . . . . . . . . . 14
7. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11 7.3. Revision -02 . . . . . . . . . . . . . . . . . . . . . . . 15
7.1. Normative References . . . . . . . . . . . . . . . . . . . 11 7.4. Revision -04 . . . . . . . . . . . . . . . . . . . . . . . 15
7.2. Informative References . . . . . . . . . . . . . . . . . . 12 8. References . . . . . . . . . . . . . . . . . . . . . . . . . . 15
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12 8.1. Normative References . . . . . . . . . . . . . . . . . . . 15
8.2. Informative References . . . . . . . . . . . . . . . . . . 16
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 16
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 Mobile or prefixes to a Mobile Router for use on the links in the Mobile
Network. DHCPv6 prefix delegation [RFC3633] (DHCPv6PD) can be used Network. DHCPv6 prefix delegation [RFC3633] (DHCPv6PD) can be used
for this configuration task. for this configuration task.
2. Terminology 2. Terminology
The key words MUST, MUST NOT, REQUIRED, SHALL, SHALL NOT, SHOULD, The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this document are to be "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
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 [RFC3775]: IPv6 specification [RFC3775]:
home agent (HA) home agent (HA)
home link home link
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 [RFC4886]: Network terminology document [RFC4885]:
Mobile Router (MR) Mobile Router (MR)
Mobile Network Mobile Network (NEMO)
mobile host (MH) 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 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. Application of DHCPv6 prefix delegation to mobile networks for 3. Application of DHCPv6 prefix delegation to mobile networks for
delegation of home prefixes delegation of home prefixes
The NEMO Basic protocol [RFC3963] extends the mobile IPv6 protocol The NEMO Basic protocol [RFC3963] extends the mobile IPv6 protocol
[RFC3775] to enable network mobility. In this extension, a MR uses [RFC3775] to enable network mobility. In this extension, an MR uses
the mobile IPv6 protocol to establish and maintain a session with its the mobile IPv6 protocol to establish and maintain a session with its
HA, and uses bidirectional tunneling between the MR and HA to provide HA, and uses bidirectional tunneling between the MR and HA to provide
a path through which nodes attached to links in the Mobile Network a path through which nodes attached to links in the Mobile Network
can maintain connectivity with nodes not in the Mobile Network. can maintain connectivity with nodes not in the Mobile Network.
The requirements for NEMO [RFC4885] include the ability of the MR to The requirements for NEMO [RFC4885] include the ability of the MR to
receive delegated prefixes that can then be assigned to links in the receive delegated prefixes that can then be assigned to links in the
Mobile Network. DHCPv6PD can be used to meet this requirement for Mobile Network. DHCPv6PD can be used to meet this requirement for
prefix delegation. prefix delegation.
skipping to change at page 4, line 35 skipping to change at page 4, line 35
assumed to be acting as a DHCPv6PD DR or relay agent and the MR will assumed to be acting as a DHCPv6PD DR or relay agent and the MR will
be assumed to be acting as a RR. be assumed to be acting as a RR.
If the HA is acting as relay agent, some other device acts as the DR. If the HA is acting as relay agent, some other device acts as the DR.
For example, the server providing DHCPv6 service in the home network For example, the server providing DHCPv6 service in the home network
might also provide NEMO DHCPv6PD service. Or, a home network with might also provide NEMO DHCPv6PD service. Or, a home network with
several HAs might configure one of those HAs as a DHCPv6PD server several HAs might configure one of those HAs as a DHCPv6PD server
while the other HAs act as relay agents. while the other HAs act as relay agents.
The HA and MR exchange DHCPv6PD protocol messages through the tunnel The HA and MR exchange DHCPv6PD protocol messages through the tunnel
connecting them. The tunnel acts as the link labeled "DSL to connecting them (as specified in RFC3775). The tunnel acts as the
subscriber premises" in figure 1 of the DHCPv6PD specification. link labeled "DSL to subscriber premises" in figure 1 of the DHCPv6PD
specification. See Figure 1 for different possible deployment
topologies.
---- /-----------\ ----
| MR |-----| Internet |-----| HA |
|(RR)| \-----------/ |(DR)|
---- ----
---- /-----------\ ----- ------
| MR |-----| Internet |-----| HA |-----|DHCPv6|
|(RR)| \-----------/ |(DRA)| |Server|
---- ----- ------
----- /-----------\ -----
| MR |----| Internet |-----| HA |
|(RR) | \-----------/ |(DR) |
|(DRA)| -----
-----
Figure 1: Different topologies of the application of DHCPv6PD to NEMO
for delegation of MNPs
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 HA data structures required as
a side effect of prefix delegation are specified by the particular a side effect of prefix delegation are specified by the particular
network mobility protocol. For example, in the case of Basic Network network mobility protocol. For example, in the case of Basic Network
Mobility Support [RFC3963], the HA would add an entry in its binding Mobility Support [RFC3963], the HA would add an entry in its binding
cache registering the delegated prefix to the MR to which the prefix cache registering the delegated prefix to the MR to which the prefix
was delegated. was delegated.
3.1. When the MR uses DHCPv6 3.1. When the MR uses DHCPv6
The MR initiates a DHCPv6 message exchange for prefix delegation The MR initiates a DHCPv6 message exchange for prefix delegation
whenever it establishes an MR-HA tunnel to its HA. If the MR does whenever it establishes an MR-HA tunnel to its HA. If the MR does
not have any active delegated prefixes (with unexpired leases), the not have any active delegated prefixes (with unexpired leases), the
MR initiates a DHCPv6 message exchange with a DHCPv6 Solicit message MR initiates a DHCPv6 message exchange with a DHCPv6 Solicit message
as described in section 17 of RFC 3315 and section 12.1 of RFC 3633. as described in section 17 of RFC 3315 and section 12.1 of RFC 3633.
If the MR has one or more active delegated prefixes, the MR initiates Once the MR has been delegated a set of prefixes from the HA, the MR
a DHCPv6 message exchange with a DHCPv6 Rebind message as described sends a new Binding Update including the delegated prefixes, carried
in section 18.1.2 of RFC 3315 and section 12.1 of RFC 3633. in Mobile Network Prefix options (see Figure 2). Note that this
requires a minor modification to the NEMO Basic Support protocol as
described in RFC 3963. RFC 3963 does not assume the MR can change
from implicit to explicit BU signaling mode, while this specification
requires the MR to first perform a MIPv6 registration to the HA
providing DHCPv6PD services (via implicit signaling, no MNP carried
in the BU), then obtain a set of delegated prefixes via DHCPv6PD, and
then send a new BU to the Home Agent, now carrying the delegated
prefixes as Mobile Network Prefixes (explicit signaling mode).
In case the MR has one or more active delegated prefixes, the MR
initiates a DHCPv6 message exchange with a DHCPv6 Rebind message as
described in section 18.1.2 of RFC 3315 and section 12.1 of RFC 3633.
In this case, only one BU signaling sequence is required.
MR HA
(RR) (DR)
| Binding Update |
|------------------------>|
| (HoA, CoA) |
| |
| Binding Ack |
|<------------------------|
| |
| DHCPv6 Solicit |
|--=====================->|
| |
| DHCPv6 Advertise |
|<-=====================--|
| |
| DHCPv6 Request |
|--=====================->|
| |
| DHCPv6 Reply |
|<-=====================--|
| (Mobile Network Prefix) |
| |
| Binding Update |
|------------------------>|
| (HoA, CoA, MNP) |
| |
| Binding Ack |
|<------------------------|
| |
Figure 2: Signaling sequence for the case the HA acts as DHCPv6PD
Delegating Router
3.2. Use of MR-HA tunnel for DHCPv6 messages 3.2. Use of MR-HA tunnel for DHCPv6 messages
The DHCPv6 specification requires the use of link-local unicast and The DHCPv6 specification requires the use of link-local unicast and
link-local scope multicast addresses in DHCPv6 messages (except in link-local scope multicast addresses in DHCPv6 messages (except in
certain cases as defined in section 22.12 of the DHCPv6 certain cases as defined in section 22.12 of the DHCPv6
specification). Section 10.4.2 of the mobile IPv6 specification specification). Section 10.4.2 of the mobile IPv6 specification
describes forwarding of intercepted packets, and the third paragraph describes forwarding of intercepted packets, and the third paragraph
of that section begins: of that section begins:
However, packets addressed to the mobile node's link-local address However, packets addressed to the mobile node's link-local address
MUST NOT be tunneled to the mobile node. MUST NOT be tunneled to the mobile node.
The DHCPv6 messages exchanged between the HA and the MR originate The DHCPv6 messages exchanged between the HA and the MR originate
only with the HA and the MR, and therefore are not "intercepted only with the HA and the MR, and therefore are not "intercepted
packets" and may be sent between the HA and the MR through the packets" (i.e. the sender of the packets is a third node on the home
tunnel. link) and may be sent between the HA and the MR through the tunnel.
Even though the MR-HA tunnel is a point to point connection, the MR Even though the MR-HA tunnel is a point to point connection, the MR
SHOULD use multicast DHCPv6 messages as described in RFC 3315 over SHOULD use multicast DHCPv6 messages as described in RFC 3315 over
that tunnel. that tunnel.
3.3. DHCPv6 Relay Agent for transmission of DHCPv6 messages 3.3. DHCPv6 Relay Agent for transmission of DHCPv6 messages
A DHPCv6 relay agent function [RFC3315] can be used as an alternative A DHPCv6 relay agent function [RFC3315] can be used as an alternative
to multicast DHCPv6 messages over the tunnel between the MR and the to multicast DHCPv6 messages over the tunnel between the MR and the
HA. In this configuration, the relay agent function is co-located in HA. In this configuration, the relay agent function is co-located in
the MR with the DHCPv6 client function. Rather than using multicast the MR with the DHCPv6 client function (see Figure 3. Rather than
to send DHCPv6 messages through the tunnel to the DHCPv6 server, the using multicast to send DHCPv6 messages through the tunnel to the
DHCPv6 client in the MR hands any outbound DHCPv6 messages to the co- DHCPv6 server, the DHCPv6 client in the MR hands any outbound DHCPv6
located relay agent. Responses from the DHCPv6 server are delivered messages to the co-located relay agent. Responses from the DHCPv6
to the relay agent function in the MR, which extracts the server are delivered to the relay agent function in the MR, which
encapsulated message and delivers it to the DHCPv6 client in the MR. extracts the encapsulated message and delivers it to the DHCPv6
client in the MR.
MR
(RR) HA
(DRA) (DR)
| Binding Update |
|------------------------>|
| (HoA, CoA) |
| |
| Binding Ack |
|<------------------------|
-- | |
/ \ | |
\ *| |
DHCPv6 -- >| DHCPv6 Solicit |
Solicit |--=====================->|
| |
| DHCPv6 Advertise |
-- |<-=====================--|
/ \ | |
\ *| DHCPv6 Request |
DHCPv6 -- >|--=====================->|
Request | |
| DHCPv6 Reply |
|<-=====================--|
| (Mobile Network Prefix) |
| |
| Binding Update |
|------------------------>|
| (HoA, CoA, MNP) |
| |
| Binding Ack |
|<------------------------|
| |
Figure 3: Signaling sequence for the case a DHCPv6 relay agent is co-
located in the MR
3.3.1. Relay agent configuration 3.3.1. 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 MR allows the MR to
unicast DHCPv6 messages to the DHCPv6 server. The relay agent must unicast DHCPv6 messages to the DHCPv6 server. The relay agent must
be configured with the address of the DHCPv6 server or another DHCPv6 be configured with the address of the DHCPv6 server or another DHCPv6
relay agent that will forward message on to a DHCPv6 server. For the relay agent that will forward message on to a DHCPv6 server. For the
purposes of NEMO, the relay agent assumes that the HA for the MR purposes of NEMO, the relay agent assumes that the HA for the MR
hosts the next hop in the path the to the DHCPv6 server: either the hosts the next hop in the path the to the DHCPv6 server: either the
DHCPv6 server or a relay agent that will forward message to the DHCPv6 server or a relay agent that will forward message to the
DHCPv6 server. Therefore, if the MR acts as a DHCPv6 relay agent, DHCPv6 server. Therefore, if the MR acts as a DHCPv6 relay agent,
the MR MUST configure the DHCPv6 relay agent to forward DHCPv6 the MR MUST configure the DHCPv6 relay agent to forward DHCPv6
messages to the HA. messages to the HA.
3.3.2. Transmission of DHCPv6 messages 3.3.2. Transmission of DHCPv6 messages
In this configuration, when the DHCPv6 client in the MR sends a In this configuration, i.e., a DHCPv6 relay agent is used and co-
message, it hands the message to the DHCPv6 relay agent in the MR. located in the MR, when the DHCPv6 client in the MR sends a message,
The way in which this handoff takes place is beyond the scope of this it hands the message to the DHCPv6 relay agent in the MR. The way in
document. The relay agent encapsulates the message from the client which the message is passed to the DHCP relay agent is beyond the
according to RFC 3315 in a Relay-forward message and sends the scope of this document. The relay agent encapsulates the message
resulting DHCPv6 message to the HA. The relay agent sets the fields from the client according to RFC 3315 in a Relay-forward message and
in the Relay-forward message as follows: sends the resulting DHCPv6 message to the HA. The relay 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 A non-link-local address from the MR interface to the link-address A non-link-local address from the MR interface (e.g.,
tunnel between the HA and MR home address or, in case the HoA belongs to the MNP,
the address of the MR's egress interface of the MR
when attached to the Home Link) of the tunnel between
the HA and MR
peer-address A non-link-local address from the MR interface to the peer-address A non-link-local address from the MR interface (e.g.,
tunnel between the HA and MR home address or, in case the HoA belongs to the MNP,
the address of the MR's egress interface of the MR
when attached to the Home Link) of the tunnel between
the HA and 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.
3.3.3. Receipt of DHCPv6 messages 3.3.3. Receipt of DHCPv6 messages
In this configuration, messages from the DHCPv6 server will be In this configuration, messages from the DHCPv6 server will be
returned to the DHCPv6 relay agent, with the message for the DHCPv6 returned to the DHCPv6 relay agent, with the message for the DHCPv6
client encapsulated in the Relay Message option [RFC3315] in a Relay- client encapsulated in the Relay Message option [RFC3315] in a Relay-
reply message. The relay agent function extracts the message for the reply message. The relay agent function extracts the message for the
client from the Relay Message option and hands the message to the client from the Relay Message option and hands the message to the
DHCPv6 client in the MR. The way in which this handoff takes place DHCPv6 client in the MR. The way in which, the message is passed to
is beyond the scope of this document. the client is beyond the scope of this document.
3.4. Exchanging DHCPv6 messages when MR is at home 3.4. Exchanging DHCPv6 messages when MR is at home
When the MR is on its home link, the HA uses the home link to When the MR is on its home link, the HA uses the home link to
exchange DHCPv6PD messages with the MR. It is the responsibility of exchange DHCPv6PD messages with the MR. It is the responsibility of
the implementation to determine when the MR is on its home link and the implementation to determine when the MR is on its home link and
to avoid use of any existing tunnel. to avoid use of any existing tunnel.
3.5. Selecting an HA that provides DHCPv6PD 3.5. Selecting an HA 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 an HA are required to
provide DHCPv6PD. Therefore, when selecting an HA, a MR that provide DHCPv6PD. Therefore, when selecting an HA, an MR that
requires DHCPv6PD service must identify an HA that will provide the requires DHCPv6PD service must identify an HA that will provide the
service. The MR can determine if an HA provides DHCPv6PD by service. The MR can determine if an HA provides DHCPv6PD by
initiating a DHCPv6 message exchange in which the MR requests initiating a DHCPv6 message exchange in which the MR requests
delegated prefix(es). If the HA does not respond or responds but delegated prefix(es). If the HA does not respond or responds but
does not delegate any prefix(es) in its response, the MR assumes that does not delegate any prefix(es) in its response, the MR assumes that
the HA does not provide DHCPv6PD service. The MR continues to query the HA does not provide DHCPv6PD service. The MR continues to query
all candidate HAs until it finds an HA that provides DHCPv6PD. all candidate HAs until it finds an HA that provides DHCPv6PD. Note
that in this particular case, the MR has also to setup a tunnel with
each HA (this requires the MR to perform an MIPv6 registration) it
queries.
Querying an HA to determine if it provides DHCPv6PD requires a small Querying an HA to determine if it provides DHCPv6PD requires a small
modification to the operation of DHCPv6 as described in RFC 3315. modification to the operation of DHCPv6 as described in RFC 3315.
Under normal circumstances, a host will continue to send DHCPv6 Under normal circumstances, a host will continue to send DHCPv6
Solicit messages until it receives a response (see Section 17 of RFC Solicit messages until it receives a response (see Section 17 of RFC
3315). However, an HA may choose not to respond to the Solicit 3315). However, an HA may choose not to respond to the Solicit
messages from the MR because the HA does not provide DHCPv6. messages from the MR because the HA does not provide DHCPv6.
Therefore, when querying an HA to determine if the HA provides Therefore, when querying an HA to determine if the HA provides
DHCPv6PD service, the MR MUST discontinue sending Solicit messages to DHCPv6PD service, the MR MUST discontinue sending Solicit messages to
the HA after sending 6 Solicit messages, and conclude that the HA the HA after sending 6 Solicit messages, and conclude that the HA
will not provide DHCPv6PD service. 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 BU message.
The MR may choose to probe the HAs for DHCPv6PD service sequentially It is recommended that the MR uses a sequential probing of the HAs
or in parallel. for DHCPv6PD service.
3.6. Minimizing DHCPv6PD messages 3.6. Minimizing DHCPv6PD messages
DHCPv6PD in a Mobile Network can be combined with the Rapid Commit DHCPv6PD in a Mobile Network can be combined with the Rapid Commit
option [RFC3315] to provide DHCPv6 prefix delegation with a two option [RFC3315] to provide DHCPv6 prefix delegation with a two
message exchange between the mobile node and the DHCPv6PD DR. message exchange between the mobile node and the DHCPv6PD DR.
3.7. Location of DHCPv6PD Delegating Router function 3.7. Location of DHCPv6PD Delegating Router function
Support of DHCPv6PD for a Mobile Network is optional. Support of DHCPv6PD for a Mobile Network is optional.
skipping to change at page 7, line 51 skipping to change at page 11, line 7
The use of a DHCPv6 relay agent in DHCPv6PD may require "a protocol The use of a DHCPv6 relay agent in DHCPv6PD may require "a protocol
or other out-of-band communication to add routing information for or other out-of-band communication to add routing information for
delegated prefixes into the provider edge router" (section 14 of RFC delegated prefixes into the provider edge router" (section 14 of RFC
3633). If the DHCPv6PD DR function is implemented in the HA for the 3633). If the DHCPv6PD DR function is implemented in the HA for the
MR, no relay agent function is required. MR, no relay agent function is required.
It may be desirable to use a single DR to manage RRs in a network It may be desirable to use a single DR to manage RRs in a network
with multiple HAs. In this scenario, the HAs will act as DHCP relay with multiple HAs. In this scenario, the HAs will act as DHCP relay
agents, forwarding messages between the RRs and the DR. agents, forwarding messages between the RRs and the DR.
Use of the DHCPv6 relay agent function with DHCPv6PD requires that The use of the DHCPv6 relay agent function with DHCPv6PD requires
there be some mechanism through which routing information for the that there be some mechanism through which routing information for
delegated prefixes can be added to the appropriate routing the delegated prefixes can be added to the appropriate routing
infrastructure. If the HA is acting as a DHCPv6 relay agent, the HA infrastructure. If the HA is acting as a DHCPv6 relay agent, the HA
SHOULD add a route to the delegated prefix and advertise that route SHOULD add a route to the delegated prefix and advertise that route
after receiving a binding update for the prefix from the RR after receiving a binding update for the prefix from the RR
[RFC3963]. [RFC3963]. Note that such binding update is received after the first
binding update message which is sent by the MR in order to set-up the
bidirectional tunnel (see Figure 4).
MR HA DHCPv6
(RR) (DRA) Server
| Binding Update | |
|------------------------>| |
| (HoA, CoA) | |
| | |
| Binding Ack | |
|<------------------------| |
| | |
| DHCPv6 Solicit | DHCPv6 Solicit |
|--=====================->|------------------------>|
| | |
| DHCPv6 Advertise | DHCPv6 Advertise |
|<-=====================--|<------------------------|
| | |
| DHCPv6 Request | DHCPv6 Request |
|--=====================->|------------------------>|
| | |
| DHCPv6 Reply | DHCPv6 Reply |
|<-=====================--|<------------------------|
| (Mobile Network Prefix) | (Mobile Network Prefix) |
| | |
| Binding Update | |
|------------------------>| |
| (HoA, CoA, MNP) | ( HA starts ) |
| | ( advertising ) |
| Binding Ack | ( routes to ) |
|<------------------------| ( the MNP ) |
| | |
Figure 4: Signaling sequence for the case the HA acts as DHCPv6 relay
agent
In particular, if the MR uses NEMO explicit mode, then it must add In particular, if the MR uses NEMO explicit mode, then it must add
the delegated prefix to the prefix list in the Binding Update the delegated prefix to the prefix list in the Binding Update
messages. If the binding cache is cleared before the prefix valid messages. If the binding cache is cleared before the prefix valid
lifetime, the MR might bind that prefix again using explicit mode, lifetime, the MR might bind that prefix again using explicit mode,
till the lifetime expires. till the lifetime expires.
In implicit mode, the HA must save the delegated prefix with the In implicit mode, the HA must save the delegated prefix with the
binding cache entry (BDE) of the Mobile Router. When the BCE is binding cache entry (BCE) of the Mobile Router. When the BCE is
cleared, the HA loses the information about the delegated prefix. cleared, the HA loses the information about the delegated prefix.
Because the MR will use DHCPv6 when it reestablishes its tunnel to Because the MR will use DHCPv6 when it reestablishes its tunnel to
the HA (see Section 3.1), the HA will be able to add the delegated the HA (see Section 3.1), the HA will be able to add the delegated
prefix back to the BCE. prefix back to the BCE.
At the time this draft was written, one way in which a DR can At the time this document was written, one way in which a DR can
explicitly notify a relay agent about delegated prefixes, is to use explicitly notify a relay agent about delegated prefixes, is to use
the "DHCP Relay Agent Assignment Notification Option" the "DHCP Relay Agent Assignment Notification Option"
[I-D.ietf-dhc-dhcpv6-agentopt-delegate]. [I-D.ietf-dhc-dhcpv6-agentopt-delegate].
Another alternative, if the RR is part of the same administrative Another alternative, if the RR is part of the same administrative
domain as the home network to which it is attached through the HA, domain as the home network to which it is attached through the HA,
and the RR can be trusted, the RR can use a routing protocol like and the RR can be trusted, the RR can use a routing protocol like
OSPF to advertise any delegated prefixes. OSPF to advertise any delegated prefixes.
NEMO explicit mode is recommended to take advantage of the function NEMO explicit mode is recommended to take advantage of the function
already defined for NEMO. already defined for NEMO.
3.8. Other DHCPv6 functions 3.8. Other DHCPv6 functions
The DHCPv6 messages exchanged between the MR and the HA may also be The DHCPv6 messages exchanged between the MR and the HA may also be
used for other DHCPv6 functions in addition to DHCPv6PD. For used for other DHCPv6 functions in addition to DHCPv6PD. For
example, the HA may assign global addresses to the MR and may pass example, the HA may assign global addresses to the MR and may pass
other configuration information such as a list of available DNS other configuration information such as a list of available DNS
recursive name servers [RFC3646] to the MR using the same DHCPv6 recursive name servers [RFC3646] to the MR using the same DHCPv6
messages as used for DHCPV6PD. messages as used for DHCPV6PD.
The HA may act as a DHCPv6 relay agent for MHs while it acts as a DR The HA may act as a DHCPv6 relay agent for MHs while it acts as a DR
for MRs. for MRs.
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
Mobile Networks. It does not introduce any additional security Mobile Networks. It does not introduce any additional security
skipping to change at page 9, line 30 skipping to change at page 13, line 22
If the HA and DHCPv6 PD functions are not provided by the same If the HA and DHCPv6 PD functions are not provided by the same
physical node, the HA will act as a DHCPv6 relay agent between the MR physical node, the HA will act as a DHCPv6 relay agent between the MR
and the DHCPv6 server. In this scenario, the mobile network and the DHCPv6 server. In this scenario, the mobile network
infrastructure will only protect the DHCPv6 traffic between the RR infrastructure will only protect the DHCPv6 traffic between the RR
(MR) and the relay agent (HA). The following text, based on Section (MR) and the relay agent (HA). The following text, based on Section
21.1 of RFC 3315, describes how appropriate security can be provided 21.1 of RFC 3315, describes how appropriate security can be provided
between a DHCPv6 relay agent and server. between a DHCPv6 relay agent and server.
DHCPv6 relay agents and servers MAY use IPsec mechanisms for IPv6 DHCPv6 relay agents and servers MAY use IPsec mechanisms for IPv6
[RFC2401] to exchange messages securely. DHCPv6 relay agents and [RFC4301] to exchange messages securely. DHCPv6 relay agents and
servers that support secure relay agent to server or relay agent servers that support secure relay agent to server or relay agent
to relay agent communication use IPsec under the following to relay agent communication use IPsec under the following
conditions: conditions:
Selectors DHCPv6 relay agents are manually configured with Selectors DHCPv6 relay agents are manually configured with
the addresses of the DHCPv6 server to which DHCPv6 the addresses of the DHCPv6 server to which DHCPv6
messages are to be forwarded. Each DHCPv6 server messages are to be forwarded. Each DHCPv6 server
that will be using IPsec for securing DHCPv6 that will be using IPsec for securing DHCPv6
messages must also be configured with a list of messages must also be configured with a list of
the DHCPv6 relay agents to which messages will be the DHCPv6 relay agents to which messages will be
skipping to change at page 10, line 15 skipping to change at page 14, line 7
Key management If the HA providing the DHCPv6 relay agent Key management If the HA providing the DHCPv6 relay agent
function and the DHCPv6 servers are both function and the DHCPv6 servers are both
administered by the same organization, public key administered by the same organization, public key
schemes are not necessary. Because the relay schemes are not necessary. Because the relay
agents and servers must be manually configured, agents and servers must be manually configured,
manually configured key management may suffice, manually configured key management may suffice,
but does not provide defense against replayed but does not provide defense against replayed
messages. Accordingly, IKE with preshared secrets messages. Accordingly, IKE with preshared secrets
SHOULD be supported. SHOULD be supported.
Discussion: If NEMO may be deployed with the HA
and the DHCPv6 server in different
administrative domains, this text
should be extended to include the use
of IKE with public keys.
Security policy DHCPv6 messages between relay agents and servers Security policy DHCPv6 messages between relay agents and servers
should only be accepted from DHCPv6 peers as should only be accepted from DHCPv6 peers as
identified in the local configuration. identified in the local configuration.
Authentication Shared keys, indexed to the source IP address of Authentication Shared keys, indexed to the source IP address of
the received DHCPv6 message, are adequate in this the received DHCPv6 message, are adequate in this
application. application.
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
Mobile Networks. It does not introduce any additional IANA Mobile Networks. It does not introduce any additional IANA
considerations. considerations.
6. Change Log 6. Acknowledgments
The authors would like to thank people who have given valuable
comments on the mailing list. Specific suggestions from Ryuji
Wakikawa, George Tsirtsis, Alexandru Petrescu, Vijay Devarapalli and
Marcelo Bagnulo were incorporated into this document.
7. Change Log
This section MUST be removed before this document is published as an This section MUST be removed before this document is published as an
RFC. RFC.
6.1. Revision -00 7.1. Revision -00
This document is based on draft-ietf-nemo-dhcpv6-pd-03 and includes This document is based on draft-ietf-nemo-dhcpv6-pd-03 and includes
the use of the DHCPv6 relay agent in the MR, as described in the use of the DHCPv6 relay agent in the MR, as described in
Section 3.3, from draft-dupont-mext-dhcrelay-00. Section 3.3, from draft-dupont-mext-dhcrelay-00.
6.2. Revision -01 7.2. Revision -01
Added detail in Section 4, "Security Considerations", describing Added detail in Section 4, "Security Considerations", describing
protection required for DHCPv6 and a mechanism for protecting traffic protection required for DHCPv6 and a mechanism for protecting traffic
between the DHCPv6 relay agent and server. between the DHCPv6 relay agent and server.
Corrected minor typos. Corrected minor typos.
6.3. Revision -02 7.3. Revision -02
Removed text describing extensions to DHAAD for discovery of HA that Removed text describing extensions to DHAAD for discovery of HA that
will provide PD. will provide PD.
Added Section 3.5, "Selecting an HA that provides DHCPv6PD," which Added Section 3.5, "Selecting an HA that provides DHCPv6PD," which
describes how an MR can discover DHCPv6PD service through polling of describes how an MR can discover DHCPv6PD service through polling of
multiple HAs. multiple HAs.
Added text to Section 4, "Security Considerations", giving detail Added text to Section 4, "Security Considerations", giving detail
about the use of IPsec. about the use of IPsec.
7. References 7.4. Revision -04
7.1. Normative References Added some figures to better explaining considered topologies and
message exchanges. Credits to Alex Petrescu.
Added some text to clarify that two BUs are required, one to set up
the tunnel to the HA so the DHCPv6 signaling can be sent, and one to
register the delegated prefixes as MNPs at the HA. This updates RFC
3963 behavior (note added).
Text added to address some comments received on the MEXT mailing list
Corrected minor typos.
Enlisted Carlos J. Bernardos as co-author
8. References
8.1. Normative References
[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.
[RFC2401] Kent, S. and R. Atkinson, "Security Architecture for the
Internet Protocol", RFC 2401, November 1998.
[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,
skipping to change at page 12, line 5 skipping to change at page 16, line 15
[RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support [RFC3775] Johnson, D., Perkins, C., and J. Arkko, "Mobility Support
in IPv6", RFC 3775, June 2004. in IPv6", RFC 3775, 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.
7.2. Informative References [RFC4301] Kent, S. and K. Seo, "Security Architecture for the
Internet Protocol", RFC 4301, December 2005.
8.2. Informative References
[I-D.ietf-dhc-dhcpv6-agentopt-delegate] [I-D.ietf-dhc-dhcpv6-agentopt-delegate]
Droms, R., Volz, B., and O. Troan, "DHCPv6 Relay Agent Droms, R., Volz, B., and O. Troan, "DHCPv6 Relay Agent
Assignment Notification (RAAN) Option", Assignment Notification (RAAN) Option",
draft-ietf-dhc-dhcpv6-agentopt-delegate-04 (work in draft-ietf-dhc-dhcpv6-agentopt-delegate-04 (work in
progress), July 2009. progress), July 2009.
[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.
[RFC4886] Ernst, T., "Network Mobility Support Goals and
Requirements", RFC 4886, 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
Phone: +1 978.936.1674 Phone: +1 978.936.1674
Email: rdroms@cisco.com Email: rdroms@cisco.com
skipping to change at page 12, line 38 skipping to change at page 17, line 4
Email: rdroms@cisco.com Email: rdroms@cisco.com
Pascal Thubert Pascal Thubert
Cisco Cisco
Village d'Entreprises Green Side Village d'Entreprises Green Side
400, Avenue Roumanille 400, Avenue Roumanille
Biot - Sophia Antipolis 06410 Biot - Sophia Antipolis 06410
FRANCE FRANCE
Email: pthubert@cisco.com Email: pthubert@cisco.com
Francis Dupont Francis Dupont
ISC ISC
Email: Francis.Dupont@fdupont.fr Email: Francis.Dupont@fdupont.fr
Wassim Haddad Wassim Haddad
Ericsson Ericsson
6210 Spine Road 6210 Spine Road
Boulder, CO 80301 Boulder, CO 80301
USA USA
Phone: +1 303.473.6963 Phone: +1 303.473.6963
Email: wmhaddad@gmail.com Email: Wassim.Haddad@ericsson.com
Carlos J. Bernardos
Universidad Carlos III de Madrid
Av. Universidad, 30
Leganes, Madrid 28911
Spain
Phone: +34 91624 6236
Email: cjbc@it.uc3m.es
URI: http://www.it.uc3m.es/cjbc/
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