draft-ietf-dhc-dhcpv6-agentopt-delegate-01.txt   draft-ietf-dhc-dhcpv6-agentopt-delegate-02.txt 
dhc Group R. Droms dhc Group R. Droms
Internet-Draft B. Volz Internet-Draft B. Volz
Intended status: Informational O. Troan Intended status: Informational O. Troan
Expires: February 11, 2007 Cisco Systems, Inc. Expires: May 31, 2007 Cisco Systems, Inc.
August 10, 2006 November 27, 2006
DHCPv6 Relay Agent Assignment Notification (RAAN) Option DHCPv6 Relay Agent Assignment Notification (RAAN) Option
draft-ietf-dhc-dhcpv6-agentopt-delegate-01.txt draft-ietf-dhc-dhcpv6-agentopt-delegate-02.txt
Status of this Memo Status of this Memo
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aware will be disclosed, in accordance with Section 6 of BCP 79. aware will be disclosed, in accordance with Section 6 of BCP 79.
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This Internet-Draft will expire on February 11, 2007. This Internet-Draft will expire on May 31, 2007.
Copyright Notice Copyright Notice
Copyright (C) The Internet Society (2006). Copyright (C) The Internet Society (2006).
Abstract Abstract
The DHCP Relay Agent Assignment Notification (RAAN) option is sent The DHCP Relay Agent Assignment Notification (RAAN) option is sent
from a DHCP server to a DHCP relay agent to inform the relay agent of from a DHCP server to a DHCP relay agent to inform the relay agent of
IPv6 addresses that have been assigned or IPv6 prefixes that have IPv6 addresses that have been assigned or IPv6 prefixes that have
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encapsulates address and prefix options to indicate that an address encapsulates address and prefix options to indicate that an address
or prefix has been assigned. The option may also carry other or prefix has been assigned. The option may also carry other
information required by the network element for configuration related information required by the network element for configuration related
to the assigned address or prefix. to the assigned address or prefix.
For example, a network administrator uses the RAAN option to inform a For example, a network administrator uses the RAAN option to inform a
relay agent of a prefix that has been delegated through DHCP PD to a relay agent of a prefix that has been delegated through DHCP PD to a
DHCP client. The relay agent notifies the network element on which DHCP client. The relay agent notifies the network element on which
it is implemented of the delegation information so the network it is implemented of the delegation information so the network
element can add routing information about the delegated prefix into element can add routing information about the delegated prefix into
the appropriate routing protocols. the routing infrastructure.
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,
SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this document are to be SHOULD NOT, RECOMMENDED, MAY, and OPTIONAL in this document are to be
interpreted as described in RFC 2119 [1]. interpreted as described in RFC 2119 [1].
The term "DHCP" in this document refers to DHCP for IPv6, as defined The term "DHCP" in this document refers to DHCP for IPv6, as defined
in RFC 3315 [2]. The terms "DHCP prefix delegation" and "DHCP PD" in RFC 3315 [2]. The terms "DHCP prefix delegation" and "DHCP PD"
refer DHCP for IPv6 prefix delegation, as defined in RFC 3633 [3] refer DHCP for IPv6 prefix delegation, as defined in RFC 3633 [3]
Additional terms used in the description of DHCP and DHCP prefix Additional terms used in the description of DHCP and DHCP prefix
delegation are defined in RFC 3315 and RFC 3633. In this document delegation are defined in RFC 3315 and RFC 3633. In this document
"assigning" an IPv6 prefix is equivalent to "delegating" a prefix. "assigning" an IPv6 prefix is equivalent to "delegating" a prefix.
3. Option semantics 3. Option Semantics and Usage
The RAANn option carries information about assigned IPv6 addresses The RAAN option carries information about assigned IPv6 addresses and
and prefixes. It encapsulates an IA Address option (RFC 3315) or an prefixes. It encapsulates IA Address options (RFC 3315) and/or IA
IA Prefix option (RFC 3633), and possibly other options that carry Prefix options (RFC 3633), and possibly other options that carry
other information related to the assigned IPv6 address or prefix. other information related to the assigned IPv6 address or prefix.
The DHCP server MAY include this option in a Reply message sent to a
client that includes assigned addresses and/or prefixes. If the DHCP
server does include this option in a Reply message, it MUST include
it in the option area of the Relay-reply message sent to the relay
agent intended as the recipient of the option.
The DHCP server is responsible for synchronizing any state created by The DHCP server is responsible for synchronizing any state created by
a node through the use of the RAAN option. For example, if a DHCP a node through the use of the RAAN option. For example, if a DHCP
server receives a Release message for a delegated prefix, it causes server receives a Release message for a delegated prefix, it causes
the node to delete any state associated with that prefix by sending the node to delete any state associated with that prefix by sending a
an RAAN option containing an IA Prefix option with the released RAAN option containing an IA Prefix option with the released prefix
prefix and a valid lifetime of zero. and a valid lifetime of zero.
A relay agent that receives this option SHOULD pass the information
to the node in which the relay agent is instantiated. The node MAY
make use of the information received from the relay agent.
If a node creates state based on the information included in this When a DHCP server sends this option to a relay agent, it MUST
option, it MUST remove that state when the lifetime as specified in include all addresses and prefixes assigned to the client on the link
the option expires. to which the option refers at the time the option is sent.
Examples of use: Examples of use:
o Populate an ACL with an assigned IPv6 address if the network o Populate an ACL with an assigned IPv6 address if the network
device in which the relay agent is instantiated implements a security policy requires limiting IPv6 forwarding to devices that
security policy limiting IPv6 forwarding to devices that have have obtained an address through DHCP
obtained an address through DHCP
o Inject routing information into a routing infrastructure about a o Inject routing information into a routing infrastructure about a
delegated prefix on behalf of a requesting router delegated prefix on behalf of a requesting router
4. Option format 4. Relay Agent Behavior
A relay agent that wants information from the server in a RAAN option
includes an ORO requesting the RAAN option in its Relay-Forw message.
A relay agent may do this for any relayed message, regardless of the
message type or the message contents.
When a relay agent receives a Relay-Reply message containing a RAAN
option, the relay agent may forward that option data to the node in
which the relay agent is instantiated. If no RAAN option is included
in the Relay-Reply, the relay agent MUST NOT assume anything with
regard to RAAN data and MUST NOT forward any indication to the node
in which the relay agent is instantiated.
If a node creates state based on the information included in this
option, it MUST remove that state when the lifetime as specified in
the option expires.
5. Server Behavior
When a server is responding to a request and the ORO contains an RAAN
option, the server SHOULD include a RAAN option with all of the
addresses and prefixes that have been (or are being assigned) to the
client. If no addresses or prefixes are assigned, the server SHOULD
send a RAAN option with no addresses or prefixes.
If the DHCP server does include this option in a Relay-Reply message,
it MUST include it in the option area of the Relay-Reply message sent
to the relay agent intended as the recipient of the option.
If the message received from the client contains no Client Identifier
option or the server is otherwise unable to identify the client or
the client's link (perhaps because of missing or invalid data in the
request), the server MUST NOT include a RAAN option in the response.
6. Option format
The RAAN option has the following format: The RAAN option has the following format:
0 1 2 3 0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| option-code | length | | option-code | length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| encapsulated-options | | encapsulated-options |
. . . .
. . . .
. . . .
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_AGENT_NOTIFY (TBD) option-code OPTION_AGENT_NOTIFY (TBD)
length length of encapsulated options, in octets length length of encapsulated options, in octets
encapsulated-options DHCP options to be delivered by the Relay Agent encapsulated-options DHCP options to be delivered by the relay agent
Assignment Notification option Assignment Notification option
5. Encapsulating DHCP options in the RAAN Option 7. Encapsulating DHCP options in the RAAN Option
The contents of options encapsulated in the RAAN option are The contents of options encapsulated in the RAAN option are
interpreted according to the use of those options in the node on interpreted according to the use of those options in the node on
which the relay agent is implemented. For the purposes of address which the relay agent is implemented. For the purposes of address
and prefix assignment, the uses of the DHCP IA Address and IA Prefix and prefix assignment, the uses of the DHCP IA Address and IA Prefix
options are defined in this document. options are defined in this document.
Note that the contents of these options are not necessarily the same Note that the contents of these options are not necessarily the same
as in the corresponding options sent to the DHCP client. For as in the corresponding options sent to the DHCP client.
example, the node that receives the information from these options
may be instructed to use the information for a shorter period of time
than the client by setting a shorter valid-lifetime in the this
option.
5.1. IA Address option 7.1. IA Address option
The fields in an IA Address option (OPTION_IAADDR, option code 5) are The fields in an IA Address option (OPTION_IAADDR, option code 5) are
used as follows: used as follows:
IPv6 address The IPv6 address assigned in this DHCP message IPv6 address The IPv6 address assigned in this DHCP message
preferred-lifetime Not used at the time this document was published preferred-lifetime Not used by the relay agent; the server SHOULD
set this field to the preferred-lifetime of the
valid-lifetime The expiration lifetime of the information carried in corresponding IA Address options in the message
this IA Address option, expressed in units of seconds; the to be forwarded to the client
expiration-lifetime is a relative time, giving the duration valid-lifetime The lifetime of the information carried in this
relative to the current time of the information in this IA Address IA Address option, expressed in units of seconds;
option; if the valid-lifetime is 0, the information is no longer if the valid-lifetime is 0, the information is no
valid. longer valid
IAaddr-options Not used IAaddr-options Not used by the relay agent; the server SHOULD
set this field to the IAaddr-options of the
corresponding IA Address option in the message to
be forwarded to the client
5.2. IA Prefix option 7.2. IA Prefix option
The fields in an IA Prefix option (OPTION_IAPREFIX, option code 28) The fields in an IA Prefix option (OPTION_IAPREFIX, option code 28)
are used as follows: are used as follows:
preferred-lifetime Not used preferred-lifetime Not used by the relay agent; the server SHOULD
set this field to the preferred-lifetime of the
corresponding IA Prefix options in the message to
be forwarded to the client
valid-lifetime The expiration lifetime of the information carried in valid-lifetime The lifetime of the information carried in this
this IA Prefix option, expressed in units of seconds; the IA Prefix option, expressed in units of seconds;
expiration-lifetime is a relative time, giving the duration if the valid-lifetime is 0, the information is no
relative to the current time of the information in this IA Prefix longer valid
option; if the valid-lifetime is 0, the information is no longer
valid.
prefix-length length for this prefix in bits prefix-length length for this prefix in bits
IPv6-prefix The IPv6 prefix assigned in this DHCP message IPv6-prefix The IPv6 prefix assigned in this DHCP message
IAprefix-options Not used at the time this document was published IAprefix-options Not used by the relay agent; the server SHOULD
set this field to the IAprefix-options of the
corresponding IA Prefix option in the message to
be forwarded to the client
6. Requesting assignment information from the DHCP server 8. Requesting assignment information from the DHCP server
If a relay agent requires the DHCP server to provide information If a relay agent requires the DHCP server to provide information
about assigned addresses and prefixes, it MUST include an Option about assigned addresses and prefixes, it MUST include an Option
Request option, requesting the Assignment Notification option, as Request option, requesting the Assignment Notification option, as
described in section 22.7 of RFC 3315. described in section 22.7 of RFC 3315.
7. Reordering received DHCP messages 9. Reordering received DHCP messages
The relay agent MUST use the Server Reply Sequence Number (SRSN) The relay agent MUST use the Server Reply Sequence Number (SRSN)
option [4] to detect and discard RAAN options contained in DHCP option [4] to detect and discard RAAN options contained in DHCP
messages that are received out of order. messages that are received out of order.
8. IANA considerations 10. IANA considerations
IANA is requested to assign an option code from the "DHCPv6 and IANA is requested to assign an option code from the "DHCPv6 and
DHCPv6 options" registry DHCPv6 options" registry
http://www.iana.org/assignments/dhcpv6-parameters to http://www.iana.org/assignments/dhcpv6-parameters to
OPTION_AGENT_NOTIFY. OPTION_AGENT_NOTIFY.
9. Security considerations 11. Security considerations
Security issues related to DHCP are described in RFC 3315 and RFC Security issues related to DHCP are described in RFC 3315 and RFC
3633. 3633.
The RAAN option may be used to mount a denial of service attack by The RAAN option may be used to mount a denial of service attack by
causing a node to incorrectly populate an ACL or incorrectly causing a node to incorrectly populate an ACL or incorrectly
configure routing protocol information for a delegated prefix. This configure routing information for a delegated prefix. This option
option may also be used to insert invalid prefixes into the routing may also be used to insert invalid prefixes into the routing
infrastruture or add invalid IP addresses to ACLs in nodes. infrastructure or add invalid IP addresses to ACLs in nodes.
Communication between a server and a relay agent, and communication Communication between a server and a relay agent, and communication
between relay agents, can be secured through the use of IPSec, as between relay agents, can be secured through the use of IPSec, as
described in section 21.1 of RFC 3315. described in section 21.1 of RFC 3315.
10. Changes in this revision 12. Changes log
If this section is included in the document when it is submitted for If this section is included in the document when it is submitted for
publication, the RFC Editor is requested to remove it. publication, the RFC Editor is requested to remove it.
Changes in rev -01: Changes in rev -01:
o Added section describing use of "Server Reply Sequence Number" o Added section describing use of "Server Reply Sequence Number"
option to allow resequencing of out-of-order messages option to allow resequencing of out-of-order messages
11. Normative References Changes in rev -02:
o Made editorial change in section 1: s/the appropriate routing
protocols/the routing infrastructure/
o Updated first paragraph in Section 3 to allow multiple IA Address
options and/or IA Prefix options
o Renamed section "Options Semantics and Usage"
o Added paragraph to section "Option Semantics and Usage" requiring
that the DHCP server must include all addresses/prefixes for the
client (on that link) in the RAAN option
o Added list of use cases to section "Option Semantics and Usage"
o Added section "Relay Agent Behavior"
o Added section "Server Behavior"; moved second paragraph of section
"Option Semantics and Usage" to "Server Behavior"
o Updated reference to draft-ietf-dhc-dhcpv6-srsn-option-00
o Clarified descriptions of various option fields in section
"Encapsulating DHCP options in the RAAN Option"
13. Normative References
[1] Bradner, S., "Key words for use in RFCs to Indicate Requirement [1] 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.
[2] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M. [2] Droms, R., Bound, J., Volz, B., Lemon, T., Perkins, C., and M.
Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)", Carney, "Dynamic Host Configuration Protocol for IPv6 (DHCPv6)",
RFC 3315, July 2003. RFC 3315, July 2003.
[3] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host [3] Troan, O. and R. Droms, "IPv6 Prefix Options for Dynamic Host
Configuration Protocol (DHCP) version 6", RFC 3633, Configuration Protocol (DHCP) version 6", RFC 3633,
December 2003. December 2003.
[4] Volz, B. and R. Droms, "DHCPv6 Server Reply Sequence Number [4] Volz, B. and R. Droms, "DHCPv6 Server Reply Sequence Number
Option", draft-volz-dhc-dhcpv6-srsn-option-00 (work in Option", draft-ietf-dhc-dhcpv6-srsn-option-00 (work in
progress), August 2006. progress), November 2006.
Authors' Addresses Authors' Addresses
Ralph Droms Ralph Droms
Cisco Systems, Inc. Cisco Systems, Inc.
1414 Massachusetts Avenue 1414 Massachusetts Avenue
Boxborough, MA 01719 Boxborough, MA 01719
USA USA
Phone: +1 978.936.1674 Phone: +1 978.936.1674
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