draft-ietf-dhc-dhcpv6-solmaxrt-update-04.txt   draft-ietf-dhc-dhcpv6-solmaxrt-update-05.txt 
dhc R. Droms dhc R. Droms
Internet-Draft Cisco Systems Internet-Draft Cisco Systems
Updates: 3315 (if approved) September 13, 2013 Updates: 3315 (if approved) September 14, 2013
Intended status: Standards Track Intended status: Standards Track
Expires: March 17, 2014 Expires: March 18, 2014
Modification to Default Values of SOL_MAX_RT and INF_MAX_RT Modification to Default Values of SOL_MAX_RT and INF_MAX_RT
draft-ietf-dhc-dhcpv6-solmaxrt-update-04 draft-ietf-dhc-dhcpv6-solmaxrt-update-05
Abstract Abstract
This document updates RFC 3315 by redefining the default values for This document updates RFC 3315 by redefining the default values for
SOL_MAX_RT and INF_MAX_RT, and defining options through which a SOL_MAX_RT and INF_MAX_RT, and defining options through which a
DHCPv6 server can override the client's default value for SOL_MAX_RT DHCPv6 server can override the client's default value for SOL_MAX_RT
and INF_MAX_RT with new values. and INF_MAX_RT with new values.
Status of This Memo Status of This Memo
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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
working documents as Internet-Drafts. The list of current Internet- working documents as Internet-Drafts. The list of current Internet-
Drafts is at http://datatracker.ietf.org/drafts/current/. Drafts is at http://datatracker.ietf.org/drafts/current/.
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 March 17, 2014. This Internet-Draft will expire on March 18, 2014.
Copyright Notice Copyright Notice
Copyright (c) 2013 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
Provisions Relating to IETF Documents Provisions Relating to IETF Documents
(http://trustee.ietf.org/license-info) in effect on the date of (http://trustee.ietf.org/license-info) in effect on the date of
publication of this document. Please review these documents publication of this document. Please review these documents
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SOL_MAX_RT. SOL_MAX_RT.
2. 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].
3. Updates to SOL_MAX_RT and INF_MAX_RT in 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 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: OLD:
INF_MAX_RT 120 secs Max Information-request timeout value INF_MAX_RT 120 secs Max Information-request timeout value
NEW: NEW:
SOL_MAX_RT 3600 secs Max Information-request timeout value 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 or Information-request satisfactory response will send Solicit or Information-request
messages with the same initial frequency and exponential backoff as messages with the same initial frequency and exponential backoff as
specified in sections 17.1.2 and 18.1.5 of RFC 3315 [RFC3315]. specified in sections 17.1.2 and 18.1.5 of RFC 3315. However, the
However, the long term behavior of these DHCPv6 clients will be to long term behavior of these DHCPv6 clients will be to send a Solicit
send a Solicit or Information-request message every 3600 seconds or Information-request message every 3600 seconds rather than every
rather than every 120 seconds, significantly reducing the aggregated 120 seconds, significantly reducing the aggregated traffic at the
traffic at the DHCPv6 server. DHCPv6 server.
4. 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 Section 3. One use for option replaces the default value defined in Section 3. One use for
the SOL_MAX_RT option is to set a longer value for SOL_MAX_RT, which the SOL_MAX_RT option is to set a longer value for SOL_MAX_RT, which
reduces the Solicit traffic from a client that has not received a reduces the Solicit traffic from a client that has not received a
response to its Solicit messages. response to its Solicit messages.
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option-len 4. option-len 4.
INF_MAX_RT value Overriding value for INF_MAX_RT INF_MAX_RT value Overriding value for INF_MAX_RT
in seconds; MUST be in range: in seconds; MUST be in range:
60 <= "value" <= 86400 (1 day) 60 <= "value" <= 86400 (1 day)
Figure 2: INF_MAX_RT option format Figure 2: INF_MAX_RT option format
6. Updates for SOL_MAX_RT and INF_MAX_RT options to RFC 3315 6. Updates for SOL_MAX_RT and INF_MAX_RT options to RFC 3315
Update to RFC 3315 [RFC3315], section 17.1.3: Update to RFC 3315, section 17.1.3:
OLD: OLD:
The client MUST ignore any Advertise message that includes a Status The client MUST ignore any Advertise message that includes a Status
Code option containing the value NoAddrsAvail, with the exception Code option containing the value NoAddrsAvail, with the exception
that the client MAY display the associated status message to the that the client MAY display the associated status message to the
user. user.
NEW: NEW:
The client MUST ignore any Advertise message that includes a Status The client MUST ignore any Advertise message that includes a Status
Code option containing the value NoAddrsAvail, with the exception Code option containing the value NoAddrsAvail, with the exception
that the client MUST process an included SOL_MAX_RT option and MUST that the client MUST process an included SOL_MAX_RT option and MUST
process an included INF_MAX_RT option and MAY display the associated process an included INF_MAX_RT option and MAY display the associated
status message to the user. status message to the user.
Update to RFC 3315 [RFC3315], section 17.2.2: Update to RFC 3315, section 17.2.2:
OLD: OLD:
If the server will not assign any addresses to any IAs in a If the server will not assign any addresses to any IAs in a
subsequent Request from the client, the server MUST send an subsequent Request from the client, the server MUST send an
Advertise message to the client that includes only a Status Code Advertise message to the client that includes only a Status Code
option with code NoAddrsAvail and a status message for the user, a option with code NoAddrsAvail and a status message for the user, a
Server Identifier option with the server's DUID, and a Client Server Identifier option with the server's DUID, and a Client
Identifier option with the client's DUID. Identifier option with the client's DUID.
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NEW: NEW:
A client is not expected to listen for a response during the entire A client is not expected to listen for a response during the entire
period between transmission of Solicit or Information-Request period between transmission of Solicit or Information-Request
messages. messages.
7. DHCPv6 Client Behavior 7. DHCPv6 Client Behavior
A DHCPv6 client MUST include the SOL_MAX_RT option code in any Option A DHCPv6 client MUST include the SOL_MAX_RT option code in any Option
Request option [RFC3315] it sends as required by RC 3315. Request option [RFC3315] it sends as required by RFC 3315.
A DHCPv6 client MUST include the INF_MAX_RT option code in any Option A DHCPv6 client MUST include the INF_MAX_RT option code in any Option
Request option [RFC3315] it sends as required by RFC 3315. Request option it sends as required by RFC 3315.
A DHCPv6 client MUST silently ignore any SOL_MAX_RT or INF_MAX_RT A DHCPv6 client MUST silently ignore any SOL_MAX_RT or INF_MAX_RT
option values that are less than 60 or more than 86400. option values that are less than 60 or more than 86400.
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
containing a valid value for SOL_MAX_RT, the client MUST set its containing a valid value for SOL_MAX_RT, the client MUST set its
internal SOL_MAX_RT parameter to the value contained in the internal SOL_MAX_RT parameter to the value contained in the
SOL_MAX_RT option. This value of SOL_MAX_RT is then used by the SOL_MAX_RT option. This value of SOL_MAX_RT is then used by the
retransmission mechanism defined in sections 17.1.2 and 14 of RFC retransmission mechanism defined in sections 17.1.2 and 14 of RFC
3315 [RFC3315]. 3315.
If a DHCPv6 client receives a message containing a INF_MAX_RT option If a DHCPv6 client receives a message containing a INF_MAX_RT option
containing a valid value for INF_MAX_RT, the client MUST set its containing a valid value for INF_MAX_RT, the client MUST set its
internal INF_MAX_RT parameter to the value contained in the internal INF_MAX_RT parameter to the value contained in the
INF_MAX_RT option. This value of INF_MAX_RT is then used by the INF_MAX_RT option. This value of INF_MAX_RT is then used by the
retransmission mechanism defined in sections 18.1.5 and 14 of RFC retransmission mechanism defined in sections 18.1.5 and 14 of RFC
3315 [RFC3315]. 3315.
8. DHCPv6 Server Behavior 8. DHCPv6 Server Behavior
Sections 17.2.2 and 18.2 of [RFC3315] govern server operation in Sections 17.2.2 and 18.2 of RFC 3315 govern server operation in
regards to option assignment. As a convenience to the reader, we regards to option assignment. As a convenience to the reader, we
mention here that the server will send option SOL_MAX_RT and mention here that the server will send option SOL_MAX_RT and
INF_MAX_RT only if configured with specific values for them and the INF_MAX_RT only if configured with specific values for them and the
client requested those options using Option Request Option. client requested those options using Option Request Option.
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 encapsulated option in, e.g., body of the message to client, not as a encapsulated option in, e.g.,
an IA_NA, IA_TA [RFC3315] or IA_PD [RFC3633] option. an IA_NA, IA_TA [RFC3315] or IA_PD [RFC3633] option.
The DHCPv6 server MAY include the INF_MAX_RT option in any response The DHCPv6 server MAY include the INF_MAX_RT option in any response
it sends to a client that has included the INF_MAX_RT option code in it sends to a client that has included the INF_MAX_RT option code in
an Option Request option. The INF_MAX_RT option is sent in the main an Option Request option. The INF_MAX_RT option is sent in the main
body of the message to client, not as a encapsulated option in, e.g., body of the message to client, not as a encapsulated option in, e.g.,
an IA_NA, IA_TA [RFC3315] or IA_PD [RFC3633] option. an IA_NA, IA_TA or IA_PD option.
9. DHCPv6 Relay Agent Behavior Text 9. DHCPv6 Relay Agent Behavior Text
There are no additional requirements for relays. There are no additional requirements for relays.
10. Security Considerations 10. 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. A malicious DHCPv6 server might cause a
cause a client to set its SOL_MAX_RT and INF_MAX_RT parameters to an client to set its SOL_MAX_RT and INF_MAX_RT parameters to an
arbitrarily high value with the SOL_MAX_RT and INF_MAX_RT options, arbitrarily high value with the SOL_MAX_RT and INF_MAX_RT options,
which may cause an undue delay in a client completing its DHCPv6 which may cause an undue delay in a client completing its DHCPv6
protocol transaction in the case no other valid response is protocol transaction in the case no other valid response is received.
received.. Assuming the client also receives a response from a valid Assuming the client also receives a response from a valid DHCPv6
DHCPv6 server, large values for SOL_MAX_RT and INF_MAX_RT will not server, large values for SOL_MAX_RT and INF_MAX_RT will not have any
have any effect. effect.
11. Acknowledgments 11. Acknowledgments
Tomek Mrugalski edited the text for compliance with draft-ietf-dhc- Tomek Mrugalski edited the text for compliance with draft-ietf-dhc-
option-guidelines [I-D.ietf-dhc-option-guidelines] and added option-guidelines [I-D.ietf-dhc-option-guidelines] and added
important details to the Security Considerations section. important details to the Security Considerations section.
12. IANA Considerations 12. IANA Considerations
IANA is requested to assign one option code each for IANA is requested to assign one option code each for
 End of changes. 16 change blocks. 
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