draft-ietf-6man-maxra-04.txt   rfc8319.txt 
IPv6 Maintenance S. Krishnan Internet Engineering Task Force (IETF) S. Krishnan
Internet-Draft Kaloom Request for Comments: 8319 Kaloom
Updates: 4861 (if approved) J. Korhonen Updates: 4861 J. Korhonen
Intended status: Standards Track Broadcom Category: Standards Track Nordic Semiconductor ASA
Expires: June 1, 2018 S. Chakrabarti ISSN: 2070-1721 S. Chakrabarti
Ericsson Verizon
E. Nordmark E. Nordmark
Arista Networks Zededa
A. Yourtchenko A. Yourtchenko
cisco Cisco
November 28, 2017 February 2018
Support for adjustable maximum router lifetimes per-link Support for Adjustable Maximum Router Lifetimes per Link
draft-ietf-6man-maxra-04
Abstract Abstract
The IPv6 Neighbor Discovery protocol specifies the maximum time The IPv6 Neighbor Discovery protocol specifies the maximum time
allowed between sending unsolicited multicast Router Advertisements allowed between sending unsolicited multicast Router Advertisements
from a router interface as well as the maximum router lifetime. It (RAs) from a router interface as well as the maximum router lifetime.
also allows the limits to be overridden by link-layer specific It also allows the limits to be overridden by documents that are
documents. This document allows for overriding these values on a specific to the link layer. This document allows for overriding
per-link basis. these values on a per-link basis.
Status of This Memo This document specifies updates to the IPv6 Neighbor Discovery
Protocol (RFC 4861) to increase the maximum time allowed between
sending unsolicited multicast RAs from a router interface as well as
to increase the maximum router lifetime.
This Internet-Draft is submitted in full conformance with the Status of This Memo
provisions of BCP 78 and BCP 79.
Internet-Drafts are working documents of the Internet Engineering This is an Internet Standards Track document.
Task Force (IETF). Note that other groups may also distribute
working documents as Internet-Drafts. The list of current Internet-
Drafts is at https://datatracker.ietf.org/drafts/current/.
Internet-Drafts are draft documents valid for a maximum of six months This document is a product of the Internet Engineering Task Force
and may be updated, replaced, or obsoleted by other documents at any (IETF). It represents the consensus of the IETF community. It has
time. It is inappropriate to use Internet-Drafts as reference received public review and has been approved for publication by the
material or to cite them other than as "work in progress." Internet Engineering Steering Group (IESG). Further information on
Internet Standards is available in Section 2 of RFC 7841.
This Internet-Draft will expire on June 1, 2018. Information about the current status of this document, any errata,
and how to provide feedback on it may be obtained at
https://www.rfc-editor.org/info/rfc8319.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2018 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
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publication of this document. Please review these documents publication of this document. Please review these documents
carefully, as they describe your rights and restrictions with respect carefully, as they describe your rights and restrictions with respect
to this document. Code Components extracted from this document must to this document. Code Components extracted from this document must
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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.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 3
3. Relationship between AdvDefaultLifetime and MaxRtrAdvInterval 3 3. Relationship between AdvDefaultLifetime and MaxRtrAdvInterval 3
4. Updates to RFC4861 . . . . . . . . . . . . . . . . . . . . . 4 4. Updates to RFC 4861 . . . . . . . . . . . . . . . . . . . . . 4
5. Host Behavior . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Host Behavior . . . . . . . . . . . . . . . . . . . . . . . . 5
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . 5
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 8. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 8.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5 8.2. Informative References . . . . . . . . . . . . . . . . . 6
9.2. Informative References . . . . . . . . . . . . . . . . . 5 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 6
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 7
1. Introduction 1. Introduction
IPv6 Neighbor Discovery relies on IP multicast based on the IPv6 Neighbor Discovery relies on IP multicast based on the
expectation that multicast makes efficient use of available bandwidth expectation that multicast makes efficient use of available bandwidth
and avoids generating interrupts in the network nodes. On some and avoids generating interrupts in the network nodes. On some data
datalink layers multicast may not be natively supported. On such link layers, multicast may not be natively supported. On such links,
links, any possible reduction of multicast traffic will be highly any possible reduction of multicast traffic will be highly
beneficial. Unfortunately, due to the fixed protocol constants beneficial. Unfortunately, due to the fixed protocol constants
specified in [RFC4861], it is difficult to relax the multicast timers specified in [RFC4861], it is difficult to relax the multicast timers
for neighbor discovery. There are already link technology specific for Neighbor Discovery. There are already clarifications specific to
clarifications describing how to tune the Neighbor Discovery Protocol the link technology about how to tune the Neighbor Discovery Protocol
(NDP) constants for certain systems with in order to reduce excess (NDP) constants for certain systems in order to reduce excess NDP
NDP traffic. e.g. [RFC6459][RFC7066] contain such clarifications for traffic. For example, [RFC6459] and [RFC7066] contain such
3GPP cellular links. clarifications for 3GPP cellular links.
This document specifies updates to the IPv6 Neighbor Discovery This document specifies updates to the IPv6 Neighbor Discovery
Protocol [RFC4861] for increasing the the maximum time allowed Protocol [RFC4861] to increase the maximum time allowed between
between sending unsolicited multicast Router Advertisements (RA) from sending unsolicited multicast RAs from a router interface as well as
a router interface as well as for the maximum router lifetime. to increase the maximum router lifetime.
2. Terminology 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", "NOT RECOMMENDED", "MAY", and
document are to be interpreted as described in [RFC2119]. "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here.
3. Relationship between AdvDefaultLifetime and MaxRtrAdvInterval 3. Relationship between AdvDefaultLifetime and MaxRtrAdvInterval
MaxRtrAdvInterval is an upper bound on the time between which two MaxRtrAdvInterval is an upper bound on the time between which two
successive Router Advertisement messages are sent. Therefore one successive Router Advertisement messages are sent. Therefore, one
might reason about the relationship between these two values in terms might reason about the relationship between these two values in terms
of a ratio K=AdvDefaultLifetime/MaxRtrAdvInterval, which expresses of a ratio K = AdvDefaultLifetime / MaxRtrAdvInterval, which
how many Router Advertisements will be guaranteed to be sent before expresses how many Router Advertisements are guaranteed to be sent
the router lifetime expires. before the router lifetime expires.
Assuming unicast Solicited Router Advertisements or a perfectly Assuming unicast Solicited Router Advertisements or a perfectly
stable network, on a theoretically perfect link with no losses, it stable network, on a theoretically perfect link with no losses, it
would have been sufficient to have K just above 1 - so that the sent would be sufficient to have K just above 1, so that the sent Router
Router Advertisement refreshes the router entry just before it Advertisement refreshes the router entry just before it expires. On
expires. On the real links which allow for some loss, one would need the real links that allow for some loss, one would need to use K > 2
to use K>2 in order to minimize the chances of a single router in order to minimize the chances of a single Router Advertisement
advertisement loss causing a loss of the router entry. loss causing a loss of the router entry.
The exact calculation will depend on the packet loss probability. An The exact calculation will depend on the packet loss probability. An
example: if we take a ballpark value of 1% probability of a packet example: if we take a ballpark value of 1% probability of a packet
loss, then K=2 will give 0.01% percent chance of an outage due to a loss, then K = 2 will give 0.01% chance of an outage due to a packet
packet loss, K=3 will give 0.0001% chance of an outage, and so forth. loss, K = 3 will give 0.0001% chance of an outage, and so forth. To
To reverse the numbers, with these parameters, K~=1 gives 99% reverse the numbers, with these parameters, K ~= 1 gives 99%
reliability, K~=2 gives 99.99% reliability, and K~=3 gives 99.9999% reliability, K ~= 2 gives 99.99% reliability, and K ~= 3 gives
reliability - the latter should be good enough for a lot of 99.9999% reliability -- which should be good enough for a lot of
scenarios. scenarios.
In a network with higher packet loss probabilities or if the higher In a network with higher packet loss probabilities or if higher
reliability is desired, the K might be chosen to be even higher. On reliability is desired, the K might be chosen to be even higher. On
the other hand, some of the data link layers provide reliable the other hand, some of the data link layers provide reliable
delivery at layer 2 - so there one might even consider using the delivery at Layer 2, so there one might even consider using the
"theoretical" value of K just above 1. Since the choice of these two "theoretical" value of K just above 1. Since the choice of these two
parameters does not impact interoperability per se, this document parameters does not impact interoperability per se, this document
does not impose any specific constraints on their values other than does not impose any specific constraints on their values other than
providing the guidelines in this section, therefore each individual providing the guidelines in this section. Therefore, each individual
link can optimize accordingly to its use case. link can optimize according to its use case.
Also AdvDefaultLifetime MUST be set to a value greater than or equal Also, AdvDefaultLifetime MUST be set to a value greater than or equal
to the selected MaxRtrAdvInterval. Otherwise, a router lifetime is to the selected MaxRtrAdvInterval. Otherwise, a router lifetime is
guaranteed to expire before the new Router Advertisement has a chance guaranteed to expire before the new Router Advertisement has a chance
to be sent, thereby creating an outage. to be sent, thereby creating an outage.
4. Updates to RFC4861 4. Updates to RFC 4861
This document updates Section 4.2 and Section 6.2.1. of [RFC4861] to This document updates Sections 4.2 and 6.2.1 of [RFC4861] to change
update the following router configuration variables. the following router configuration variables.
In Section 4.2, inside the paragraph that defines Router Lifetime, In Section 4.2, inside the paragraph that defines Router Lifetime,
change 9000 to 65535 seconds. change 9000 to 65535 seconds.
In Section 6.2.1, inside the paragraph that defines In Section 6.2.1, inside the paragraph that defines
MaxRtrAdvInterval, change 1800 to 65535 seconds. MaxRtrAdvInterval, change 1800 to 65535 seconds.
In Section 6.2.1, inside the paragraph that defines In Section 6.2.1, inside the paragraph that defines
AdvDefaultLifetime, change 9000 to 65535 seconds. AdvDefaultLifetime, change 9000 to 65535 seconds.
As explained in Section 3, the relationship between MaxRtrAdvInterval As explained in Section 3, the probability of packet loss must be
and AdvDefaultLifetime must be chosen to take into account the considered when choosing the relationship between MaxRtrAdvInterval
probability of packet loss. and AdvDefaultLifetime.
5. Host Behavior 5. Host Behavior
Legacy hosts on a link with updated routers may have issues with a Legacy hosts on a link with updated routers may have issues with a
Router Lifetime of more than 9000 seconds. In the few Router Lifetime of more than 9000 seconds. In the few
implementations we have tested with general purpose operating implementations we have tested with general-purpose operating
systems, there does not seem to be any issues with setting this field systems, there does not seem to be any issue with setting this field
to more than 9000, but there might be implementations that to more than 9000, but there might be implementations that
incorrectly (since RFC4861 requires receivers to handle any value) incorrectly reject such RAs (since RFC 4861 requires receivers to
reject such RAs. handle any value).
6. Security Considerations 6. Security Considerations
On a link where router advertisements are few and far between, the On a link where Router Advertisements are few and far between, the
detrimental effects of a rogue router that sends an unsolicited RA detrimental effects of a rogue router that sends an unsolicited RA
are greatly increased. These rogue RAs can be prevented by using are greatly increased. These rogue RAs can be prevented by using
approaches like RA-Guard [RFC6105] and SeND [RFC3971] approaches like RA-Guard [RFC6105] and SEcure Neighbor Discovery
(SEND) [RFC3971].
7. IANA Considerations 7. IANA Considerations
This document does not require any IANA action. This document has no IANA actions.
8. Acknowledgements
The authors would like to thank the members of the 6man efficient ND
design team for their comments that led to the creation of this
draft. The authors would also like to thank Lorenzo Colitti, Erik
Kline, Jeena Rachel John, Brian Carpenter, Tim Chown, Fernando Gont,
Warren Kumari and Adam Roach for their comments and suggestions that
improved this document.
9. References 8. References
9.1. Normative 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, Requirement Levels", BCP 14, RFC 2119,
DOI 10.17487/RFC2119, March 1997, DOI 10.17487/RFC2119, March 1997,
<https://www.rfc-editor.org/info/rfc2119>. <https://www.rfc-editor.org/info/rfc2119>.
[RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
"Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
DOI 10.17487/RFC4861, September 2007, DOI 10.17487/RFC4861, September 2007,
<https://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
9.2. Informative References [RFC8174] Leiba, B., "Ambiguity of Uppercase vs Lowercase in
RFC 2119 Key Words", BCP 14, RFC 8174,
DOI 10.17487/RFC8174, May 2017,
<https://www.rfc-editor.org/info/rfc8174>.
8.2. Informative References
[RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander, [RFC3971] Arkko, J., Ed., Kempf, J., Zill, B., and P. Nikander,
"SEcure Neighbor Discovery (SEND)", RFC 3971, "SEcure Neighbor Discovery (SEND)", RFC 3971,
DOI 10.17487/RFC3971, March 2005, DOI 10.17487/RFC3971, March 2005,
<https://www.rfc-editor.org/info/rfc3971>. <https://www.rfc-editor.org/info/rfc3971>.
[RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J. [RFC6105] Levy-Abegnoli, E., Van de Velde, G., Popoviciu, C., and J.
Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105, Mohacsi, "IPv6 Router Advertisement Guard", RFC 6105,
DOI 10.17487/RFC6105, February 2011, DOI 10.17487/RFC6105, February 2011,
<https://www.rfc-editor.org/info/rfc6105>. <https://www.rfc-editor.org/info/rfc6105>.
skipping to change at page 5, line 42 skipping to change at page 6, line 28
T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation
Partnership Project (3GPP) Evolved Packet System (EPS)", Partnership Project (3GPP) Evolved Packet System (EPS)",
RFC 6459, DOI 10.17487/RFC6459, January 2012, RFC 6459, DOI 10.17487/RFC6459, January 2012,
<https://www.rfc-editor.org/info/rfc6459>. <https://www.rfc-editor.org/info/rfc6459>.
[RFC7066] Korhonen, J., Ed., Arkko, J., Ed., Savolainen, T., and S. [RFC7066] Korhonen, J., Ed., Arkko, J., Ed., Savolainen, T., and S.
Krishnan, "IPv6 for Third Generation Partnership Project Krishnan, "IPv6 for Third Generation Partnership Project
(3GPP) Cellular Hosts", RFC 7066, DOI 10.17487/RFC7066, (3GPP) Cellular Hosts", RFC 7066, DOI 10.17487/RFC7066,
November 2013, <https://www.rfc-editor.org/info/rfc7066>. November 2013, <https://www.rfc-editor.org/info/rfc7066>.
Acknowledgements
The authors would like to thank the members of the 6MAN efficient ND
design team for their comments that led to the creation of this
document. The authors would also like to thank Lorenzo Colitti, Erik
Kline, Jeena Rachel John, Brian Carpenter, Tim Chown, Fernando Gont,
Warren Kumari, and Adam Roach for their comments and suggestions that
improved this document.
Authors' Addresses Authors' Addresses
Suresh Krishnan Suresh Krishnan
Kaloom Kaloom
335 Rue Peel 335 Rue Peel
Montreal, QC Montreal, QC
Canada Canada
Email: suresh@kaloom.com Email: suresh@kaloom.com
Jouni Korhonen Jouni Korhonen
Broadcom Nordic Semiconductor ASA
Porkkalankatu 24 Metsanneidonkuja 10
FIN-00180 Helsinki 02130 Espoo
Finland Finland
Email: jouni.nospam@gmail.com Email: jouni.nospam@gmail.com
Samita Chakrabarti Samita Chakrabarti
Ericsson Verizon
USA United States of America
Email: samita.chakrabarti@ericsson.com Email: samita.chakrabarti@verizon.com
Erik Nordmark Erik Nordmark
Arista Networks Zededa
Santa Clara, CA Santa Clara, CA
USA United States of America
Email: nordmark@acm.org Email: nordmark@acm.org
Andrew Yourtchenko Andrew Yourtchenko
cisco Cisco
6b de Kleetlaan 6b de Kleetlaan
Diegem 1831 Diegem 1831
Belgium Belgium
Email: ayourtch@cisco.com Email: ayourtch@cisco.com
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