idnits 2.17.1 draft-ietf-idr-deprecate-as-sets-01.txt: Checking boilerplate required by RFC 5378 and the IETF Trust (see https://trustee.ietf.org/license-info): ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/1id-guidelines.txt: ---------------------------------------------------------------------------- No issues found here. Checking nits according to https://www.ietf.org/id-info/checklist : ---------------------------------------------------------------------------- No issues found here. Miscellaneous warnings: ---------------------------------------------------------------------------- == The copyright year in the IETF Trust and authors Copyright Line does not match the current year -- The document date (December 29, 2010) is 4866 days in the past. Is this intentional? Checking references for intended status: Informational ---------------------------------------------------------------------------- No issues found here. Summary: 0 errors (**), 0 flaws (~~), 1 warning (==), 1 comment (--). Run idnits with the --verbose option for more detailed information about the items above. -------------------------------------------------------------------------------- 2 Network Working Group W. Kumari 3 Internet-Draft Google, Inc. 4 Intended status: Informational December 29, 2010 5 Expires: July 2, 2011 7 Deprecation of BGP AS_SET, AS_CONFED_SET. 8 draft-ietf-idr-deprecate-as-sets-01.txt 10 Abstract 12 This document deprecates the use of the AS_SET and AS_CONFED_SET 13 types of the AS_PATH in BGPv4. This is done to simplify the design 14 and implementation of the BGP protocol and to make the semantics of 15 the originator of a route more clear. This will also simpify the 16 design, implementation and deployment of onging work in the Secure 17 Inter-Domain Routing Working Group. 19 Status of this Memo 21 This Internet-Draft is submitted in full conformance with the 22 provisions of BCP 78 and BCP 79. 24 Internet-Drafts are working documents of the Internet Engineering 25 Task Force (IETF). Note that other groups may also distribute 26 working documents as Internet-Drafts. The list of current Internet- 27 Drafts is at http://datatracker.ietf.org/drafts/current/. 29 Internet-Drafts are draft documents valid for a maximum of six months 30 and may be updated, replaced, or obsoleted by other documents at any 31 time. It is inappropriate to use Internet-Drafts as reference 32 material or to cite them other than as "work in progress." 34 This Internet-Draft will expire on July 2, 2011. 36 Copyright Notice 38 Copyright (c) 2010 IETF Trust and the persons identified as the 39 document authors. All rights reserved. 41 This document is subject to BCP 78 and the IETF Trust's Legal 42 Provisions Relating to IETF Documents 43 (http://trustee.ietf.org/license-info) in effect on the date of 44 publication of this document. Please review these documents 45 carefully, as they describe your rights and restrictions with respect 46 to this document. Code Components extracted from this document must 47 include Simplified BSD License text as described in Section 4.e of 48 the Trust Legal Provisions and are provided without warranty as 49 described in the Simplified BSD License. 51 Table of Contents 53 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . . 3 54 2. Requirements notation . . . . . . . . . . . . . . . . . . . . . 3 55 3. Terminology . . . . . . . . . . . . . . . . . . . . . . . . . . 3 56 4. Deployment and modification of behavior . . . . . . . . . . . . 3 57 5. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 4 58 6. Security Considerations . . . . . . . . . . . . . . . . . . . . 4 59 7. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 4 60 8. Normative References . . . . . . . . . . . . . . . . . . . . . 4 61 Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 5 63 1. Introduction 65 The AS_SET path segment type of the AS_PATH attribute ([RFC4271], 66 Section 4.3) is created by a router that is performing route 67 aggregation and contains an unordered set of ASs that the update has 68 traversed. The AS_CONFED_SET path segment type ([RFC5065]) of the 69 AS_PATH attribute is created by a router that is performing route 70 aggregation and contains an unordered set of Member AS Numbers in the 71 local confederation that the update has traversed (AS_CONFED_SETs are 72 very similar to AS_SETs, but are used within a confederation). 74 By performing aggregation, a router is, in essence, combining 75 multiple routes into a new route. This type of aggregation blurs the 76 semantics of what it means to originate a route. These can cause 77 operational issues that include reachability problems and traffic 78 engineering issues. 80 From analysis of past Internet routing data it is apparent that 81 aggregation that involves AS_SETs is very seldom used in practice on 82 the public network and, when it is, often contains reserved AS 83 numbers ([RFC1930]) and / or only a single AS in the AS_SET. The 84 reduction in table size provided by the aggregation is outweighed by 85 additional complexity in the BGP protocol and confusion regarding 86 what exactly is meant by originating a route. 88 2. Requirements notation 90 The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", 91 "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this 92 document are to be interpreted as described in [RFC2119]. 94 3. Terminology 96 Deprecate: To advise against the use of a feature or function. 97 Typically done before the removal of the feature or function 98 from a product. 100 4. Deployment and modification of behavior 102 Operators who are currently announcing routes containing AS_SETs or 103 AS_CONFED_SETs are advised to investigate why they are doing so and 104 withdraw these announcements (and possibly reannounce the network 105 without the aggregation). As with any change, the operator should 106 understand the full implications of the change. 108 It is worth noting that new technologies (such as those that take 109 advantage of the "X.509 Extensions for IP Addresses and AS 110 Identifiers" ([RFC3779]) MAY not support routes with AS_SETs / 111 AS_CONFED_SETs in them, and MAY treat as infeasible routes containing 112 them. 114 It is expected that, even before the deployment of these 115 technologies, operators may begin filtering routers that contain 116 AS_SETs or AS_CONFED_SETs. 118 5. IANA Considerations 120 This document contains no IANA considerations. 122 6. Security Considerations 124 By removing support for the AS_SET path segment type of the AS_PATH 125 attribute future BGP implementations can be simplified. This will 126 also simplify the design and implementation of the RPKI and systems 127 that will rely on it. By removing corner cases we remove complexity 128 and code that is not exercised very often, which decreases the attack 129 surface. 131 7. Acknowledgements 133 The author would like to thank Tony Li, Randy Bush, John Scudder, 134 Chris Morrow, Danny McPherson, Douglas Montgomery, Enke Chen, Florian 135 Weimer, Ilya Varlashkin, Jakob Heitz, John Leslie, Keyur Patel, Paul 136 Jakma, Rob Austein, Russ Housley, Sandra Murphy, Sriram Kotikalapudi, 137 Steve Bellovin, Steve Kent, Steve Padgett, Alfred Hones, Tom Petch, 138 everyone in IDR and everyone else who provided input. 140 Apologies to those who I may have missed, it was not intentional. 142 8. Normative References 144 [RFC1930] Hawkinson, J. and T. Bates, "Guidelines for creation, 145 selection, and registration of an Autonomous System (AS)", 146 BCP 6, RFC 1930, March 1996. 148 [RFC2119] Bradner, S., "Key words for use in RFCs to Indicate 149 Requirement Levels", BCP 14, RFC 2119, March 1997. 151 [RFC3779] Lynn, C., Kent, S., and K. Seo, "X.509 Extensions for IP 152 Addresses and AS Identifiers", RFC 3779, June 2004. 154 [RFC4271] Rekhter, Y., Li, T., and S. Hares, "A Border Gateway 155 Protocol 4 (BGP-4)", RFC 4271, January 2006. 157 [RFC5065] Traina, P., McPherson, D., and J. Scudder, "Autonomous 158 System Confederations for BGP", RFC 5065, August 2007. 160 Author's Address 162 Warren Kumari 163 Google, Inc. 164 1600 Amphitheatre Parkway 165 Mountain View, CA 94043 166 US 168 Phone: +1 571 748 4373 169 Email: warren@kumari.net