IPv6 Maintenance S. Krishnan Internet-Draft Ericsson Updates: 4861 (if approved) J. Korhonen Intended status: Standards Track Broadcom Expires: January 5, 2015 July 4, 2014 Support for adjustable maximum router lifetimes per-link draft-krishnan-6man-maxra-00 Abstract The neighbor discovery protocol specifies the maximum time allowed between sending unsolicited multicast Router Advertisements from a router interface as well as the maximum router lifetime. It also allows the limits to be overridden by link-layer specific documents. This document specifies a mechanism for overriding these values on a per-link basis. Status of this Memo This Internet-Draft is submitted in full conformance with the provisions of BCP 78 and BCP 79. 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 January 5, 2015. Copyright Notice Copyright (c) 2014 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 carefully, as they describe your rights and restrictions with respect to this document. Code Components extracted from this document must include Simplified BSD License text as described in Section 4.e of Krishnan & Korhonen Expires January 5, 2015 [Page 1]
Internet-Draft Adjustable Router Lifetimes July 2014 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 3. Maximum Advertisement Interval option . . . . . . . . . . . . . 3 4. Updates to RFC4861 . . . . . . . . . . . . . . . . . . . . . . 4 5. Host Behavior . . . . . . . . . . . . . . . . . . . . . . . . . 4 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 5 7. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 5 8. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 5 9. References . . . . . . . . . . . . . . . . . . . . . . . . . . 5 9.1. Normative References . . . . . . . . . . . . . . . . . . . 5 9.2. Informative References . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 6 Krishnan & Korhonen Expires January 5, 2015 [Page 2]
Internet-Draft Adjustable Router Lifetimes July 2014 1. Introduction IPv6 Neighbor Discovery relies on IP multicast with the expectation to be efficient with respect to available bandwidth and to avoid generating interrupts in the network nodes. On some datalink-layer network, for example IEEE 802.11 WiFi, this is not the case because of limitations in the services offered by the datalink-layer network [draft-vyncke-6man-mcast-not-efficient-01]. On such links any possible reduction of multicast traffic will be highly beneficial. Unfortunately, due to the fixed protocol constants specified in [RFC4861] it is difficult to relax the multicast timers for neighbor discovery. There are already link technology specific clarifications how to tune protocol constants for certain system with the expectation to reduce excess Neighbor Discovery Protocol (NDP) traffic. 3GPP cellular links are one existing example [RFC6459][RFC7066]. This document describes an IPv6 NDP [RFC4861] mechanism for specifying the the maximum time allowed between sending unsolicited multicast Router Advertisements (RA) from a router interface as well as the maximum router lifetime. 2. Terminology The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in [RFC2119]. 3. Maximum Advertisement Interval option This option is to be carried in RA messages sent out by a router on a given link. It specifies the value that the router uses for the MaxRtrAdvInterval configuration variable as specified in section 6.2.1 of [RFC4861] or an indication to the hosts on the links that there would be no periodic multicast RAs on the link. Krishnan & Korhonen Expires January 5, 2015 [Page 3]
Internet-Draft Adjustable Router Lifetimes July 2014 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 +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | Type | Length | MaxAdvInterval | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ | reserved (set to 0) | +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+ Type 8-bit identifier of the type of option. The option identifier for the MAI option will be allocated by the IANA. Length 8-bit unsigned integer. The length of the option (including the type and length fields) in units of 8 octets. It MUST be set to 1. MaxAdvInterval The value in seconds that the router is using for the MaxRtrAdvInterval configuration variable. If there are no periodic unsolicited RAs on the link this MUST be set to 0. Figure 1: Maximum Advertisement Interval Option Layout 4. Updates to RFC4861 This document updates Section 6.2.1. of [RFC4861] to update the following router configuration variables. MaxRtrAdvInterval MUST be no greater than 21845. AdvDefaultLifetime MUST be between MaxRtrAdvInterval and 3 * MaxRtrAdvInterval. This document also updates Sections 6.2.1., 6.2.2., 6.2.4. and 6.2.5. of [RFC4861] so that AdvSendAdvertisements can be set "FALSE" but the router would still continue be a router and respond to unsolicited RAs (this is indicated by advertising MaxRtrAdvInterval 0 in the Maximum Advertisement Interval Option). 5. Host Behavior The value of Maximum Advertisement Interval provided in this option is purely informational. It helps the hosts to determine how long they need to wait for an unsolicited RA before assuming that the router no longer exists. Since there is no timestamp in the received Krishnan & Korhonen Expires January 5, 2015 [Page 4]
Internet-Draft Adjustable Router Lifetimes July 2014 RA, the moment the host receives the RA the router lifetime calculated based on the indicated interval is a rough estimate. 6. Security Considerations An attacker may attempt to modify the information provided inside this option to make hosts lose their default routers unintentionally. These attacks can easily be prevented by using SeND [RFC3971] 7. IANA Considerations This document defines a new IPv6 neighbor discovery option for carrying the maximum advertisement interval. IANA is requested to assign the a new neighbor discovery option type in the registry maintained at http://www.iana.org/assignments/icmpv6-parameters <TBA> Maximum Advertisement Interval [RFC-krishnan-6man-maxra-00.txt] 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. 9. References 9.1. Normative References [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate Requirement Levels", BCP 14, RFC 2119, March 1997. [RFC3971] Arkko, J., Kempf, J., Zill, B., and P. Nikander, "SEcure Neighbor Discovery (SEND)", RFC 3971, March 2005. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. 9.2. Informative References [RFC6459] Korhonen, J., Soininen, J., Patil, B., Savolainen, T., Bajko, G., and K. Iisakkila, "IPv6 in 3rd Generation Krishnan & Korhonen Expires January 5, 2015 [Page 5]
Internet-Draft Adjustable Router Lifetimes July 2014 Partnership Project (3GPP) Evolved Packet System (EPS)", RFC 6459, January 2012. [RFC7066] Korhonen, J., Arkko, J., Savolainen, T., and S. Krishnan, "IPv6 for Third Generation Partnership Project (3GPP) Cellular Hosts", RFC 7066, November 2013. Authors' Addresses Suresh Krishnan Ericsson 8400 Decarie Blvd. Town of Mount Royal, QC Canada Phone: +1 514 345 7900 x42871 Email: suresh.krishnan@ericsson.com Jouni Korhonen Broadcom Porkkalankatu 24 FIN-00180 Helsinki Finland Email: jouni.nospam@gmail.com Krishnan & Korhonen Expires January 5, 2015 [Page 6]