--- 1/draft-ietf-v6ops-design-choices-00.txt 2014-03-06 11:14:39.520354373 -0800 +++ 2/draft-ietf-v6ops-design-choices-01.txt 2014-03-06 11:14:39.548355059 -0800 @@ -1,76 +1,78 @@ V6OPS Working Group P. Matthews Internet-Draft Alcatel-Lucent -Intended status: Informational February 14, 2013 -Expires: August 18, 2013 +Intended status: Informational V. Kuarsingh +Expires: September 7, 2014 Dyn + March 6, 2014 Design Choices for IPv6 Networks - draft-ietf-v6ops-design-choices-00 + draft-ietf-v6ops-design-choices-01 Abstract This document presents advice on the design choices that arise when designing IPv6 networks (both dual-stack and IPv6-only). The intended audience is someone designing an IPv6 network who is knowledgeable about best current practices around IPv4 network design, and wishes to learn the corresponding practices for IPv6. -Status of this Memo +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 August 18, 2013. + This Internet-Draft will expire on September 7, 2014. Copyright Notice - Copyright (c) 2013 IETF Trust and the persons identified as the + 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 the Trust Legal Provisions and are provided without warranty as described in the Simplified BSD License. Table of Contents - 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 - 2. Design Choices . . . . . . . . . . . . . . . . . . . . . . . . 3 + 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 2 + 2. Design Choices . . . . . . . . . . . . . . . . . . . . . . . 3 2.1. Mix IPv4 and IPv6 on the Same Link? . . . . . . . . . . . 3 2.2. Links with Only Link-Local Addresses? . . . . . . . . . . 4 - 2.3. Link-Local Next-Hop in a Static Route? . . . . . . . . . . 5 + 2.3. Link-Local Next-Hop in a Static Route? . . . . . . . . . 5 2.4. Separate or Combined eBGP Sessions? . . . . . . . . . . . 6 2.5. eBGP Endpoints: Global or Link-Local Addresses? . . . . . 7 - 3. General Observations . . . . . . . . . . . . . . . . . . . . . 8 + 2.6. IGP Choice . . . . . . . . . . . . . . . . . . . . . . . 8 + 3. General Observations . . . . . . . . . . . . . . . . . . . . 9 3.1. Use of Link-Local Addresses . . . . . . . . . . . . . . . 9 - 3.2. Separation of IPv4 and IPv6 . . . . . . . . . . . . . . . 9 + 3.2. Separation of IPv4 and IPv6 . . . . . . . . . . . . . . . 10 4. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 10 5. Security Considerations . . . . . . . . . . . . . . . . . . . 10 - 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10 - 7. Informative References . . . . . . . . . . . . . . . . . . . . 10 - Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 12 + 6. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 10 + 7. Informative References . . . . . . . . . . . . . . . . . . . 11 + Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 12 1. Introduction This document presents advice on the design choices that arise when designing IPv6 networks (both dual-stack and IPv6-only). The intended audience is someone designing an IPv6 network who is knowledgeable about best current practices around IPv4 network design, and wishes to learn the corresponding practices for IPv6. The focus of the document is on design choices where there are @@ -82,22 +84,23 @@ documented; otherwise the document simply summarizes the current state of the discussion. Thus this document serves to both to document the reasoning behind best current practices for IPv6, and to allow a designer to make an intelligent choice where no such consensus exists. This document does not present advice on strategies for adding IPv6 to a network, nor does it discuss transition mechanisms. For advice in these areas, see [RFC6180] for general advice, [RFC6782] for wireline service providers, [RFC6342] for mobile network providers, - [RFC5963] for exchange point operators, [I-D.ietf-v6ops-icp-guidance] - for content providers, and both [RFC4852] and + [RFC5963] for exchange point operators, [RFC6883] for content + providers, and both [RFC4852] and + [I-D.ietf-v6ops-enterprise-incremental-ipv6] for enterprises. Nor does the document cover the ins and outs of creating an IPv6 addressing plan; for advice in this area, see [RFC5375]. This document focuses on unicast network design only. It does not cover multicast, nor supporting infrastructure such as DNS. The current version is still work in progress, and it is expected that the presentation and discussion of additional design choices will be added as the document matures. @@ -338,20 +343,69 @@ local end, and no reconfiguration is required at the remote end). o Finally, a strict interpretation of RFC 2545 can be seen as forbidding running eBGP between link-local addresses, as RFC 2545 requires the BGP next-hop field to contain at least a global address. For these reasons, most operators today choose to have their eBGP sessions use global addresses. +2.6. IGP Choice + + One of the main decisions for an IPv6 implementor is the choice of + IGP (Interior Gateway Protocol) within the network. The primary + choices are the IETF protocols of RIP [RFC2080], OSPF [RFC2328] + [RFC5340] and IS-IS [RFC5120] [RFC5308], though some operators may + consider non-IETF protocols. Here we limit our discussion to the + pros and cons of OSPF vs. IS-IS. + + Considering just OSPF vs. IS-IS, the options are: + + a. Use OSPFv2 for IPv4 and OSPFv3 for IPv6, OR + + b. Use OSPFv3 for both IPv4 and IPv6, OR + + c. Use OSPFv2 for IPv4, and IS-IS for IPv6, OR + + d. Use IS-IS for IPv4 and IPv6, OR + + e. Use IS-IS for IPv4 and OSPFv3 for IPv6. + + Note that options (a), (c), and (e) involve running two different + routing protocols, while options (b) and (d) involve running just one + routing protocol. + + o A big factor in the choice is the protocol the operator is + currently using for routing IPv4. Option (e) is unlikely to be a + good choice for an operator currently using OSPF for IPv4 routing, + and similarly option (a) is unlikely to be a good choice for an + operator currently using IS-IS. + + o A pro for options (a), (c), and (e), which use two routing + protocols, is that they give a hard separation between IPv4 and + IPv6 routing. Thus a problem with one protocol or one set of + routes is unlikely to affect the other. + + o There are two cons for options (a), (c), and (e). One con is that + two sets of all the protocol mechanisms need to be maintained. On + a larger modern router, this is unlikely to be a problem, but on + some edge devices this might be an issue. The second con is that + some operational staff must be familiar with both protocols. For + many routing problems, the protocols are sufficiently similar that + they can be considered identical, but some problems require a + detailed knowledge of the differences. + + o Option (b) requires the use of new protocol extensions that allow + OSPFv3 to also route IPv4. At the time of writing, these + extensions are still quite new. + 3. General Observations There are two themes that run though many of the design choices in this document. This section presents some general discussion on these two themes. 3.1. Use of Link-Local Addresses The proper use of link-local addresses is a common theme in the IPv6 network design choices. Link-layer addresses are, of course, always @@ -417,68 +471,70 @@ Many, many people in the V6OPS working group provided comments and suggestions that made their way into this document. A partial list includes: Rajiv Asati, Fred Baker, Michael Behringer, Marc Blanchet, Ron Bonica, Randy Bush, Cameron Byrne, Brian Carpenter, KK Chittimaneni, Tim Chown, Lorenzo Colitti, Gert Doering, Bill Fenner, Kedar K Gaonkar, Chris Grundemann, Steinar Haug, Ray Hunter, Joel Jaeggli, Victor Kuarsingh, Ivan Pepelnjak, Alexandru Petrescu, Rob Shakir, Mark Smith, Jean-Francois Tremblay, Tina Tsou, Dan York, and Xuxiaohu. - I would also like to thank Pradeep Jain and Alastair Johnson for - helpful comments on a very preliminary version of this document. + The authors would also like to thank Pradeep Jain and Alastair + Johnson for helpful comments on a very preliminary version of this + document. 7. Informative References [I-D.ietf-idr-bgp-multisession] Scudder, J., Appanna, C., and I. Varlashkin, "Multisession BGP", draft-ietf-idr-bgp-multisession-07 (work in progress), September 2012. [I-D.ietf-idr-dynamic-cap] Ramachandra, S. and E. Chen, "Dynamic Capability for BGP-4", draft-ietf-idr-dynamic-cap-14 (work in progress), December 2011. [I-D.ietf-opsec-lla-only] Behringer, M. and E. Vyncke, "Using Only Link-Local - Addressing Inside an IPv6 Network", - draft-ietf-opsec-lla-only-02 (work in progress), - October 2012. + Addressing Inside an IPv6 Network", draft-ietf-opsec-lla- + only-07 (work in progress), February 2014. [I-D.ietf-v6ops-enterprise-incremental-ipv6] Chittimaneni, K., Chown, T., Howard, L., Kuarsingh, V., Pouffary, Y., and E. Vyncke, "Enterprise IPv6 Deployment - Guidelines", - draft-ietf-v6ops-enterprise-incremental-ipv6-01 (work in - progress), September 2012. + Guidelines", draft-ietf-v6ops-enterprise-incremental- + ipv6-05 (work in progress), January 2014. - [I-D.ietf-v6ops-icp-guidance] - Carpenter, B. and S. Jiang, "IPv6 Guidance for Internet - Content and Application Service Providers", - draft-ietf-v6ops-icp-guidance-05 (work in progress), - January 2013. + [RFC2080] Malkin, G. and R. Minnear, "RIPng for IPv6", RFC 2080, + January 1997. + + [RFC2328] Moy, J., "OSPF Version 2", STD 54, RFC 2328, April 1998. [RFC4852] Bound, J., Pouffary, Y., Klynsma, S., Chown, T., and D. Green, "IPv6 Enterprise Network Analysis - IP Layer 3 Focus", RFC 4852, April 2007. [RFC4861] Narten, T., Nordmark, E., Simpson, W., and H. Soliman, "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861, September 2007. [RFC5082] Gill, V., Heasley, J., Meyer, D., Savola, P., and C. Pignataro, "The Generalized TTL Security Mechanism (GTSM)", RFC 5082, October 2007. - [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, - October 2008. + [RFC5120] Przygienda, T., Shen, N., and N. Sheth, "M-ISIS: Multi + Topology (MT) Routing in Intermediate System to + Intermediate Systems (IS-ISs)", RFC 5120, February 2008. + + [RFC5308] Hopps, C., "Routing IPv6 with IS-IS", RFC 5308, October + 2008. [RFC5340] Coltun, R., Ferguson, D., Moy, J., and A. Lindem, "OSPF for IPv6", RFC 5340, July 2008. [RFC5375] Van de Velde, G., Popoviciu, C., Chown, T., Bonness, O., and C. Hahn, "IPv6 Unicast Address Assignment Considerations", RFC 5375, December 2008. [RFC5925] Touch, J., Mankin, A., and R. Bonica, "The TCP Authentication Option", RFC 5925, June 2010. @@ -489,20 +545,31 @@ [RFC6180] Arkko, J. and F. Baker, "Guidelines for Using IPv6 Transition Mechanisms during IPv6 Deployment", RFC 6180, May 2011. [RFC6342] Koodli, R., "Mobile Networks Considerations for IPv6 Deployment", RFC 6342, August 2011. [RFC6782] Kuarsingh, V. and L. Howard, "Wireline Incremental IPv6", RFC 6782, November 2012. -Author's Address + [RFC6883] Carpenter, B. and S. Jiang, "IPv6 Guidance for Internet + Content Providers and Application Service Providers", RFC + 6883, March 2013. + +Authors' Addresses Philip Matthews Alcatel-Lucent 600 March Road Ottawa, Ontario K2K 2E6 Canada Phone: +1 613-784-3139 Email: philip_matthews@magma.ca + Victor Kuarsingh + Dyn + 150 Dow Street + Manchester, NH 03101 + USA + + Email: victor@jvknet.com