draft-ietf-6man-maxra-03.txt   draft-ietf-6man-maxra-04.txt 
IPv6 Maintenance S. Krishnan IPv6 Maintenance S. Krishnan
Internet-Draft Kaloom Internet-Draft Kaloom
Updates: 4861 (if approved) J. Korhonen Updates: 4861 (if approved) J. Korhonen
Intended status: Standards Track Broadcom Intended status: Standards Track Broadcom
Expires: January 4, 2018 S. Chakrabarti Expires: June 1, 2018 S. Chakrabarti
Ericsson Ericsson
E. Nordmark E. Nordmark
Arista Networks Arista Networks
A. Yourtchenko A. Yourtchenko
cisco cisco
July 3, 2017 November 28, 2017
Support for adjustable maximum router lifetimes per-link Support for adjustable maximum router lifetimes per-link
draft-ietf-6man-maxra-03 draft-ietf-6man-maxra-04
Abstract Abstract
The neighbor discovery protocol specifies the maximum time allowed The IPv6 Neighbor Discovery protocol specifies the maximum time
between sending unsolicited multicast Router Advertisements from a allowed between sending unsolicited multicast Router Advertisements
router interface as well as the maximum router lifetime. It also from a router interface as well as the maximum router lifetime. It
allows the limits to be overridden by link-layer specific documents. also allows the limits to be overridden by link-layer specific
This document allows for overriding these values on a per-link basis. documents. This document allows for overriding these values on a
per-link basis.
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
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 https://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 January 4, 2018. This Internet-Draft will expire on June 1, 2018.
Copyright Notice Copyright Notice
Copyright (c) 2017 IETF Trust and the persons identified as the Copyright (c) 2017 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 (https://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
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
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.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2
2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . 2 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 RFC4861 . . . . . . . . . . . . . . . . . . . . . 4
5. Host Behavior . . . . . . . . . . . . . . . . . . . . . . . . 4 5. Host Behavior . . . . . . . . . . . . . . . . . . . . . . . . 4
6. Security Considerations . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . 4
7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 4
8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 4
9. References . . . . . . . . . . . . . . . . . . . . . . . . . 4 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5
9.1. Normative References . . . . . . . . . . . . . . . . . . 5 9.1. Normative References . . . . . . . . . . . . . . . . . . 5
9.2. Informative References . . . . . . . . . . . . . . . . . 5 9.2. Informative References . . . . . . . . . . . . . . . . . 5
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 5
1. Introduction 1. Introduction
IPv6 Neighbor Discovery relies on IP multicast with the expectation IPv6 Neighbor Discovery relies on IP multicast based on the
to be efficient with respect to available bandwidth and to avoid expectation that multicast makes efficient use of available bandwidth
generating interrupts in the network nodes. On some datalink layers and avoids generating interrupts in the network nodes. On some
multicast may not be natively supported. On such links any possible datalink layers multicast may not be natively supported. On such
reduction of multicast traffic will be highly beneficial. links, any possible reduction of multicast traffic will be highly
Unfortunately, due to the fixed protocol constants specified in beneficial. Unfortunately, due to the fixed protocol constants
[RFC4861] it is difficult to relax the multicast timers for neighbor specified in [RFC4861], it is difficult to relax the multicast timers
discovery. There are already link technology specific clarifications for neighbor discovery. There are already link technology specific
how to tune protocol constants for certain system with the clarifications describing how to tune the Neighbor Discovery Protocol
expectation to reduce excess Neighbor Discovery Protocol (NDP) (NDP) constants for certain systems with in order to reduce excess
traffic. 3GPP cellular links are one existing example NDP traffic. e.g. [RFC6459][RFC7066] contain such clarifications for
[RFC6459][RFC7066]. 3GPP cellular links.
This document specifies updates to the IPv6 Neighbor Discovery This document specifies updates to the IPv6 Neighbor Discovery
Protocol [RFC4861] for relaxing the the maximum time allowed between Protocol [RFC4861] for increasing the the maximum time allowed
sending unsolicited multicast Router Advertisements (RA) from a between sending unsolicited multicast Router Advertisements (RA) from
router interface as well as for the maximum router lifetime. a router interface as well as for the maximum router lifetime.
2. Terminology 2. Terminology
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 [RFC2119]. document are to be interpreted as described in [RFC2119].
3. Relationship between AdvDefaultLifetime and MaxRtrAdvInterval 3. Relationship between AdvDefaultLifetime and MaxRtrAdvInterval
MaxRtrAdvInterval is an upper bound on the time between the 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 the ratio K=AdvDefaultLifetime/MaxRtrAdvInterval, which expresses of a ratio K=AdvDefaultLifetime/MaxRtrAdvInterval, which expresses
how many Router Advertisements will be guaranteed to be sent before how many Router Advertisements will be guaranteed to be sent before
the router lifetime expiry. 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 have been sufficient to have K just above 1 - so that the sent
Router Advertisement refreshes the router entry just before it Router Advertisement refreshes the router entry just before it
expires. On the real links which allow for some loss, one would need expires. On the real links which allow for some loss, one would need
to use K>2 in order to minimize the chances of a single router to use K>2 in order to minimize the chances of a single router
advertisement loss causing a loss of the router entry. advertisement 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% percent chance of an outage due to a
packet loss, K=3 will give 0.0001% chance of an outage, and so forth. packet loss, K=3 will give 0.0001% chance of an outage, and so forth.
To reverse the numbers, with these parameters, K~=1 gives 99% To 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 99.9999%
reliability - the latter should be good enough for a lot of reliability - the latter should be good enough for a lot of
scenarios. scenarios.
In a network with higher packet loss or if the higher reliability is In a network with higher packet loss probabilities or if the higher
desired, the K might be chosen to be even higher. On the other hand, reliability is desired, the K might be chosen to be even higher. On
some of the data link layers provide reliable delivery at layer 2 - the other hand, some of the data link layers provide reliable
so there one might even consider using the "theoretical" value of K delivery at layer 2 - so there one might even consider using the
just above 1. Since the choice of these two parameters does not "theoretical" value of K just above 1. Since the choice of these two
impact the interoperability per se, this document does not impose any parameters does not impact interoperability per se, this document
specific constraints on their values other than providing the does not impose any specific constraints on their values other than
guidelines in this section, therefore each individual link can providing the guidelines in this section, therefore each individual
optimize accordingly to its use case. link can optimize accordingly 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 RFC4861
This document updates Section 6.2.1. of [RFC4861] to update the This document updates Section 4.2 and Section 6.2.1. of [RFC4861] to
following router configuration variables. update the following router configuration variables.
MaxRtrAdvInterval MUST be no greater than 65535. AdvDefaultLifetime In Section 4.2, inside the paragraph that defines Router Lifetime,
MUST either be zero (the router is not to be used as a default change 9000 to 65535 seconds.
router) or be a value between MaxRtrAdvInterval and 65535.
In Section 6.2.1, inside the paragraph that defines
MaxRtrAdvInterval, change 1800 to 65535 seconds.
In Section 6.2.1, inside the paragraph that defines
AdvDefaultLifetime, change 9000 to 65535 seconds.
As explained in Section 3, the relationship between MaxRtrAdvInterval As explained in Section 3, the relationship between MaxRtrAdvInterval
and AdvDefaultLifetime must be chosen to take into account the and AdvDefaultLifetime must be chosen to take into account the
probability of packet loss. probability of packet loss.
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
skipping to change at page 4, line 44 skipping to change at page 4, line 49
7. IANA Considerations 7. IANA Considerations
This document does not require any IANA action. This document does not require any IANA action.
8. Acknowledgements 8. Acknowledgements
The authors would like to thank the members of the 6man efficient ND 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 design team for their comments that led to the creation of this
draft. The authors would also like to thank Lorenzo Colitti, Erik draft. The authors would also like to thank Lorenzo Colitti, Erik
Kline, Jeena Rachel John, Brian Carpenter, Tim Chown and Fernando Kline, Jeena Rachel John, Brian Carpenter, Tim Chown, Fernando Gont,
Gont for their comments and suggestions that improved this document. Warren Kumari and Adam Roach for their comments and suggestions that
improved this document.
9. References 9. References
9.1. Normative References 9.1. 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,
<http://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,
<http://www.rfc-editor.org/info/rfc4861>. <https://www.rfc-editor.org/info/rfc4861>.
9.2. Informative References 9.2. 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,
<http://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,
<http://www.rfc-editor.org/info/rfc6105>. <https://www.rfc-editor.org/info/rfc6105>.
[RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen, [RFC6459] Korhonen, J., Ed., Soininen, J., Patil, B., Savolainen,
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,
<http://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, <http://www.rfc-editor.org/info/rfc7066>. November 2013, <https://www.rfc-editor.org/info/rfc7066>.
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
 End of changes. 25 change blocks. 
54 lines changed or deleted 62 lines changed or added

This html diff was produced by rfcdiff 1.46. The latest version is available from http://tools.ietf.org/tools/rfcdiff/