--- 1/draft-ietf-v6ops-reducing-ra-energy-consumption-02.txt 2015-11-05 19:15:24.627558858 -0800 +++ 2/draft-ietf-v6ops-reducing-ra-energy-consumption-03.txt 2015-11-05 19:15:24.647559342 -0800 @@ -1,19 +1,19 @@ IPv6 Operations A. Yourtchenko Internet-Draft Cisco Intended status: Best Current Practice L. Colitti -Expires: April 4, 2016 Google - October 2, 2015 +Expires: May 8, 2016 Google + November 5, 2015 Reducing energy consumption of Router Advertisements - draft-ietf-v6ops-reducing-ra-energy-consumption-02 + draft-ietf-v6ops-reducing-ra-energy-consumption-03 Abstract Frequent Router Advertisement messages can severely impact host power consumption. This document recommends operational practices to avoid such impact. Status of This Memo This Internet-Draft is submitted in full conformance with the @@ -22,21 +22,21 @@ Internet-Drafts are working documents of the Internet Engineering Task Force (IETF). Note that other groups may also distribute working documents as Internet-Drafts. The list of current Internet- Drafts is at http://datatracker.ietf.org/drafts/current/. Internet-Drafts are draft documents valid for a maximum of six months and may be updated, replaced, or obsoleted by other documents at any time. It is inappropriate to use Internet-Drafts as reference material or to cite them other than as "work in progress." - This Internet-Draft will expire on April 4, 2016. + This Internet-Draft will expire on May 8, 2016. Copyright Notice Copyright (c) 2015 IETF Trust and the persons identified as the document authors. All rights reserved. This document is subject to BCP 78 and the IETF Trust's Legal Provisions Relating to IETF Documents (http://trustee.ietf.org/license-info) in effect on the date of publication of this document. Please review these documents @@ -44,32 +44,30 @@ to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 2. Problem scenarios . . . . . . . . . . . . . . . . . . . . . . 2 2.1. Solicited multicast RAs on large networks . . . . . . . . 2 - 2.2. Frequent periodic Router Advertisements . . . . . . . . . 3 + 2.2. Frequent periodic Router Advertisements . . . . . . . . . 2 3. Consequences . . . . . . . . . . . . . . . . . . . . . . . . 3 4. Router Advertisement frequency . . . . . . . . . . . . . . . 3 5. Recommendations . . . . . . . . . . . . . . . . . . . . . . . 4 5.1. Network-side recommendations . . . . . . . . . . . . . . 4 5.2. Device-side recommendations . . . . . . . . . . . . . . . 5 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 8. Security Considerations . . . . . . . . . . . . . . . . . . . 5 - 9. References . . . . . . . . . . . . . . . . . . . . . . . . . 5 - 9.1. Normative References . . . . . . . . . . . . . . . . . . 5 - 9.2. URIs . . . . . . . . . . . . . . . . . . . . . . . . . . 6 + 9. Normative References . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction Routing information is communicated to IPv6 hosts by Router Advertisement (RA) messages [RFC4861]. If these messages are too frequent, they can severely impact power consumption on battery- powered hosts. The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", @@ -87,41 +85,49 @@ Advertisement. In the worst case, if devices are continually joining and leaving the network, and the network is large enough, then all devices on the network will receive solicited Router Advertisements at the maximum rate specified by section 6.2.6 of [RFC4861], which is one every 3 seconds. 2.2. Frequent periodic Router Advertisements Some networks send periodic multicast Router Advertisements very frequently (e.g., once every few seconds). This may be due to a - desire to ensure that hosts always have access to up-to-date router - information. This has severe impact on battery life. + desire to minimize customer impact of network renumbering events, + which in some large residential networks occur relatively frequently. + + In the presence of hosts that ignore RAs or even all IPv6 packets + when in sleep mode, such networks may see a need to send RAs + frequently in order to avoid leaving devices with non-functional IPv6 + configurations for extended periods of time. Unfortunately, this has + severe impact on battery life. 3. Consequences Observed reactions to frequent Router Advertisement messages by battery-powered devices include: o Some hosts simply experience bad battery life on these networks and otherwise operate normally. This is frustrating for users of these networks. o Some hosts react by dropping all Router Advertisement messages - when in power saving mode on any network, e.g., [1]. This causes - devices to lose connectivity when in power-saving mode, + when in power saving mode on any network, e.g., + . This + causes devices to lose connectivity when in power-saving mode, potentially disrupting background network communications, because the device is no longer able to send packets or acknowledge received traffic. o Some hosts react by dropping *all* IPv6 packets when in power - saving mode, [2]. This disrupts network communications. + saving mode, . This disrupts network communications. Compounding the problem, when dealing with devices that drop Router Advertisements when in power saving mode, some network administrators work around the problem by sending RAs even more frequently. This causes devices to engage in even more aggressive filtering. 4. Router Advertisement frequency The appropriate frequency of periodic RAs depends on how constrained the network devices are. @@ -182,70 +188,69 @@ for a limited period of time (e.g., not more than one minute) immediately after a configuration change. No protocol changes are required. Responding to Router Solicitations with unicast Router Advertisements is already allowed by section 6.2.6 of [RFC4861], and Router Advertisement intervals are already configurable by the administrator to a wide range of values. 5.2. Device-side recommendations - 1. Mobile devices that intend to maintain IPv6 connectivity while - asleep MUST NOT ignore RAs while asleep. + 1. Maintaining IPv6 connectivity requires that hosts be able to + receive periodic multicast RAs [RFC4861] Therefore, hosts that + process unicast packets sent while they are asleep MUST also + process multicast RAs sent while they are asleep. Battery- + powered hosts MAY rate-limit identical RAs if they are sent too + frequently. - 2. Mobile devices that do not intend to maintain IPv6 connectivity - while asleep SHOULD disconnect from the IPv6 network and SHOULD - reconnect to the network (including performing any DNAv6 - procedures [RFC6059], sending Router Solicitations and performing - Duplicate Address Detection) when waking up. + 2. Battery-powered devices that do not intend to maintain IPv6 + connectivity while asleep SHOULD either disconnect from the + network, abandoning all IPv6 configuration on that network, or + perform DNAv6 procedures [RFC6059] when waking up. 6. Acknowledgements - The authors wish to thank Steven Barth, Frank Bulk, David Farmer, Ray - Hunter, Erik Kline, Erik Nordmark, Alexandru Petrescu, Libor Polcak, - Mark Smith, and Jinmei Tatuya for feedback and helpful suggestions. + The authors wish to thank Steven Barth, Frank Bulk, David Farmer, + Igor Gashinsky, Ray Hunter, Erik Kline, Erik Nordmark, Alexandru + Petrescu, Libor Polcak, Mark Smith, Jinmei Tatuya and James Woodyatt + for feedback and helpful suggestions. 7. IANA Considerations None. 8. Security Considerations Misconfigured or malicious hosts sending rogue Router Advertisements [RFC6104] can also severely impact power consumption on battery- powered hosts if they send a significant number of such messages. Any IPv6 network where there is potential for misconfigured or malicious hosts should take appropriate countermeasures to mitigate the problem. -9. References - -9.1. Normative References +9. Normative References [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, DOI 10.17487/ + RFC2119, March 1997, + . [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, - September 2007. + DOI 10.17487/RFC4861, September 2007, + . [RFC6059] Krishnan, S. and G. Daley, "Simple Procedures for - Detecting Network Attachment in IPv6", RFC 6059, DOI 10 - .17487/RFC6059, November 2010, + Detecting Network Attachment in IPv6", RFC 6059, DOI + 10.17487/RFC6059, November 2010, . -9.2. URIs - - [1] https://code.google.com/p/android/issues/detail?id=32662 - - [2] http://www.gossamer-threads.com/lists/nsp/ipv6/54641 - Authors' Addresses Andrew Yourtchenko Cisco 7a de Kleetlaan Diegem, 1831 Belgium Phone: +32 2 704 5494 Email: ayourtch@cisco.com