draft-ietf-dhc-dhcpv6-solmaxrt-update-00.txt   draft-ietf-dhc-dhcpv6-solmaxrt-update-01.txt 
Network Working Group R. Droms Network Working Group R. Droms
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 3315 (if approved) December 13, 2012 Updates: 3315 (if approved) June 03, 2013
Intended status: Standards Track Intended status: Standards Track
Expires: June 16, 2013 Expires: December 05, 2013
Modification to Default Value of SOL_MAX_RT Modification to Default Value of SOL_MAX_RT
draft-ietf-dhc-dhcpv6-solmaxrt-update-00 draft-ietf-dhc-dhcpv6-solmaxrt-update-01
Abstract Abstract
This document updates RFC 3315 by redefining the default value for This document updates RFC 3315 by redefining the default values for
SOL_MAX_RT and defining an option through which a DHCPv6 server can SOL_MAX_RT and INF_MAX_RT, and defining options through which a
override the client's default value for SOL_MAX_RT with a new value. DHCPv6 server can override the client's default value for SOL_MAX_RT
and INF_MAX_RT with a new value.
Status of this Memo Status of This Memo
This Internet-Draft is submitted in full conformance with the This Internet-Draft is submitted in full conformance with the
provisions of BCP 78 and BCP 79. provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering Internet-Drafts are working documents of the Internet Engineering
Task Force (IETF). Note that other groups may also distribute Task Force (IETF). Note that other groups may also distribute
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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
and may be updated, replaced, or obsoleted by other documents at any and may be updated, replaced, or obsoleted by other documents at any
time. It is inappropriate to use Internet-Drafts as reference time. It is inappropriate to use Internet-Drafts as reference
material or to cite them other than as "work in progress." material or to cite them other than as "work in progress."
This Internet-Draft will expire on June 16, 2013. This Internet-Draft will expire on December 05, 2013.
Copyright Notice Copyright Notice
Copyright (c) 2012 IETF Trust and the persons identified as the Copyright (c) 2013 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
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include Simplified BSD License text as described in Section 4.e of include Simplified BSD License text as described in Section 4.e of
the Trust Legal Provisions and are provided without warranty as the Trust Legal Provisions and are provided without warranty as
described in the Simplified BSD License. described in the Simplified BSD License.
1. Introduction 1. Introduction
Section 5.5 of the DHCPv6 specification [RFC3315] defines the default Section 5.5 of the DHCPv6 specification [RFC3315] defines the default
value of SOL_MAX_RT to be 120 seconds. In some circumstances, this values of SOL_MAX_RT and INF_MAX_RT to be 120 seconds. In some
default will lead to an unacceptably high volume of aggregated circumstances, these defaults will lead to an unacceptably high
traffic at a DHCPv6 server. volume of aggregated traffic at a DHCPv6 server.
The change to SOL_MAX_RT is in response to DHCPv6 message rates The change to SOL_MAX_RT is in response to DHCPv6 message rates
observed at a DHCPv6 server in a deployment in which many DHCPv6 observed at a DHCPv6 server in a deployment in which many DHCPv6
clients are sending Solicit messages but the DHCPv6 server has been clients are sending Solicit messages but the DHCPv6 server has been
configured not to respond to those Solicit messages. configured not to respond to those Solicit messages. While no
explicit observations of traffic due to INF_MAX_RT have been
conducted, this document updates INF_MAX_RT for consistency with
SOL_MAX_RT.
1.1. Requirements Language 2. Requirements Language
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
document are to be interpreted as described in RFC 2119 [RFC2119]. document are to be interpreted as described in RFC 2119 [RFC2119].
2. Update to RFC 3315 3. Updates to SOL_MAX_RT and INF_MAX_RT in RFC 3315
This document changes section 5.5 of RFC 3315 [RFC3315] as follows: This document changes section 5.5 of RFC 3315 [RFC3315] as follows:
OLD: OLD:
SOL_MAX_RT 120 secs Max Solicit timeout value SOL_MAX_RT 120 secs Max Solicit timeout value
NEW: NEW:
SOL_MAX_RT 3600 secs Max Solicit timeout value SOL_MAX_RT 3600 secs Max Solicit timeout value
OLD:
INF_MAX_RT 120 secs Max Information-request timeout value
NEW:
SOL_MAX_RT 3600 secs Max Information-request timeout value
With this change, a DHCPv6 client that does not receive a With this change, a DHCPv6 client that does not receive a
satisfactory response will send Solicit messages with the same satisfactory response will send Solicit or Information-request
initial frequency and exponential backoff as specified in section messages with the same initial frequency and exponential backoff as
17.1.2 of RFC 3315 [RFC3315]. However, the long term behavior of specified in sections 17.1.2 and 18.1.5 of RFC 3315 [RFC3315].
these DHCPv6 clients will be to send a Solicit message every 3600 However, the long term behavior of these DHCPv6 clients will be to
seconds rather than every 120 seconds, significantly reducing the send a Solicit or Information-request message every 3600 seconds
aggregated traffic at the DHCPv6 server. rather than every 120 seconds, significantly reducing the aggregated
traffic at the DHCPv6 server.
3. SOL_MAX_RT option 4. SOL_MAX_RT option
A DHCPv6 server sends the SOL_MAX_RT option to a client to override A DHCPv6 server sends the SOL_MAX_RT option to a client to override
the default value of SOL_MAX_RT. The value of SOL_MAX_RT in the the default value of SOL_MAX_RT. The value of SOL_MAX_RT in the
option replaces the default value defined in RFC 3315 [RFC3315]. One option replaces the default value defined in Section 3. One use for
use for the SOL_MAX_RT option is to set a longer value for the SOL_MAX_RT option is to set a longer value for SOL_MAX_RT, which
SOL_MAX_RT, which reduces the Solicit traffic from a client that has reduces the Solicit traffic from a client that has not received a
not received a response to its Solicit messages. response to its Solicit messages.
The format of the SOL_MAX_RT option is: The format of the SOL_MAX_RT option is:
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 | option-len | | option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| SOL_MAX_RT value | | SOL_MAX_RT value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
option-code OPTION_SOL_MAX_RT (TBD). option-code OPTION_SOL_MAX_RT (TBD).
option-len 4. option-len 4.
SOL_MAX_RT value Overriding value for SOL_MAX_RT in seconds. SOL_MAX_RT value Overriding value for SOL_MAX_RT
in seconds.
Figure 1 Figure 1
A DHCPv6 client MUST include the SOL_MAX_RT option code in an Option A DHCPv6 client MUST include the SOL_MAX_RT option code in an Option
Request option [RFC3315] in any message it sends. Request option [RFC3315] in any message it sends.
The DHCPv6 server MAY include the SOL_MAX_RT option in any response The DHCPv6 server MAY include the SOL_MAX_RT option in any response
it sends to a client that has included the SOL_MAX_RT option code in it sends to a client that has included the SOL_MAX_RT option code in
an Option Request option. The SOL_MAX_RT option is sent in the main an Option Request option. The SOL_MAX_RT option is sent in the main
body of the message to client, not as a sub-option in, e.g., an body of the message to client, not as a sub-option in, e.g., an
IA_NA, IA_TA [RFC3315] or IA_PD [RFC3633] option. IA_NA, IA_TA [RFC3315] or IA_PD [RFC3633] option.
If a DHCPv6 client receives a message containing a SOL_MAX_RT option, If a DHCPv6 client receives a message containing a SOL_MAX_RT option,
the client MUST set its internal SOL_MAX_RT parameter to the value the client MUST set its internal SOL_MAX_RT parameter to the value
contained in the SOL_MAX_RT option. As a result of receiving this contained in the SOL_MAX_RT option. As a result of receiving this
option, the DHCPv6 client MUST NOT send any Solicit messages more option, the DHCPv6 client MUST NOT send any Solicit messages more
frequently than allowed by the retransmission mechanism defined in frequently than allowed by the retransmission mechanism defined in
sections 17.1.2 and 14 of RFC 3315 [RFC3315]. sections 17.1.2 and 14 of RFC 3315 [RFC3315].
4. Updates to RFC 3315 5. INF_MAX_RT option
RFC 3315 [RFC3315], section 17.1.3: A DHCPv6 server sends the INF_MAX_RT option to a client to override
the default value of INF_MAX_RT. The value of INF_MAX_RT in the
option replaces the default value defined in Section 3. One use for
the INF_MAX_RT option is to set a longer value for INF_MAX_RT, which
reduces the Solicit traffic from a client that has not received a
response to its Solicit messages.
OLD: The format of the INF_MAX_RT option is:
The client MUST ignore any Advertise message that includes a Status 0 1 2 3
Code option containing the value NoAddrsAvail, with the exception 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
that the client MAY display the associated status message to the +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
user. | option-code | option-len |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| INF_MAX_RT value |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
NEW: option-code OPTION_INF_MAX_RT (TBD).
The client MUST ignore any Advertise message that includes a Status option-len 4.
Code option containing the value NoAddrsAvail, with the exception
that the client MUST process an included SOL_MAX_RT option and MAY
display the associated status message to the user.
Figure 2 INF_MAX_RT value Overriding value for INF_MAX_RT
in seconds.
RFC 3315 [RFC3315], section 17.2.2: Figure 2: INF_MAX_RT option format
OLD: A DHCPv6 client MUST include the INF_MAX_RT option code in an Option
Request option [RFC3315] in any message it sends.
If the server will not assign any addresses to any IAs in a The DHCPv6 server MAY include the INF_MAX_RT option in any response
subsequent Request from the client, the server MUST send an it sends to a client that has included the INF_MAX_RT option code in
Advertise message to the client that includes only a Status Code an Option Request option. The INF_MAX_RT option is sent in the main
option with code NoAddrsAvail and a status message for the user, a body of the message to client, not as a sub-option in, e.g., an
Server Identifier option with the server's DUID, and a Client IA_NA, IA_TA [RFC3315] or IA_PD [RFC3633] option.
Identifier option with the client's DUID.
NEW: If a DHCPv6 client receives a message containing a INF_MAX_RT option,
the client MUST set its internal INF_MAX_RT parameter to the value
contained in the INF_MAX_RT option. As a result of receiving this
option, the DHCPv6 client MUST NOT send any Information-request
messages more frequently than allowed by the retransmission mechanism
defined in sections 18.1.5 and 14 of RFC 3315 [RFC3315].
If the server will not assign any addresses to any IAs in a 6. Updates for SOL_MAX_RT and INF_MAX_RT options to RFC 3315
subsequent Request from the client, the server MUST send an
Advertise message to the client that includes only a Status Code
option with code NoAddrsAvail and a status message for the user, a
Server Identifier option with the server's DUID, a Client
Identifier option with the client's DUID and (optionally) a
SOL_MAX_RT option.
Figure 3 Update to RFC 3315 [RFC3315], section 17.1.3:
5. Security Considerations OLD:
The client MUST ignore any Advertise message that includes a Status
Code option containing the value NoAddrsAvail, with the exception
that the client MAY display the associated status message to the
user.
NEW:
The client MUST ignore any Advertise message that includes a Status
Code option containing the value NoAddrsAvail, with the exception
that the client MUST process an included SOL_MAX_RT option and/or an
included INF_MAX_RT option and MAY display the associated status
message to the user.
Update to RFC 3315 [RFC3315], section 17.2.2:
OLD:
If the server will not assign any addresses to any IAs in a
subsequent Request from the client, the server MUST send an
Advertise message to the client that includes only a Status Code
option with code NoAddrsAvail and a status message for the user, a
Server Identifier option with the server's DUID, and a Client
Identifier option with the client's DUID.
NEW:
If the server will not assign any addresses to any IAs in a
subsequent Request from the client, the server MUST send an
Advertise message to the client that includes only a Status Code
option with code NoAddrsAvail and a status message for the user, a
Server Identifier option with the server's DUID, a Client
Identifier option with the client's DUID and (optionally)
SOL_MAX_RT and/or INF_MAX_RT options.
Add text to the end of section 14, clarifying client behavior while
waiting for a response from a server:
NEW:
A client is not expected to listen for a response during the entire
period between transmission of Solicit or Information-Request
messages.
7. Security Considerations
This document introduces one security consideration beyond those This document introduces one security consideration beyond those
described in RFC 3315 [RFC3315]. A malicious DHCPv6 server might described in RFC 3315 [RFC3315]. A malicious DHCPv6 server might
cause a client to set its SOL_MAX_RT parameter to an arbitrarily high cause a client to set its SOL_MAX_RT and INF_MAX_RT parameters to an
value with the SOL_MAX_RT option. Assuming the client also receives arbitrarily high value with the SOL_MAX_RT and INF_MAX_RT options.
a response from a valid DHCPv6 server, the large value for SOL_MAX_RT Assuming the client also receives a response from a valid DHCPv6
will not have any effect. server, large values for SOL_MAX_RT and INF_MAX_RT will not have any
effect.
6. IANA Considerations 8. IANA Considerations
IANA is requested to assign an option code from the "DHCP Option IANA is requested to assign an option code from the "DHCP Option
Codes" Registry for OPTION_SOL_MAX_RT. Codes" Registry for OPTION_SOL_MAX_RT.
7. Normative References 9. 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.
[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.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
September 2007.
Author's Address Author's Address
Ralph Droms Ralph Droms
Cisco Systems Cisco Systems
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
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