--- 1/draft-ietf-grow-wkc-behavior-00.txt 2019-01-07 08:13:36.699274423 -0800 +++ 2/draft-ietf-grow-wkc-behavior-01.txt 2019-01-07 08:13:36.719274905 -0800 @@ -1,30 +1,33 @@ Network Working Group J. Borkenhagen Internet-Draft AT&T Intended status: Standards Track R. Bush -Expires: January 19, 2019 Internet Initiative Japan +Expires: July 11, 2019 Internet Initiative Japan R. Bonica Juniper Networks S. Bayraktar Cisco Systems - July 18, 2018 + January 7, 2019 Well-Known Community Policy Behavior - draft-ietf-grow-wkc-behavior-00 + draft-ietf-grow-wkc-behavior-01 Abstract Well-Known BGP Communities are manipulated inconsistently by current - implementations. This results in difficulties for operators. It is - recommended that removal policies be applied consistently to Well- - Known Communities. + implementations. This results in difficulties for operators. + Network operators are encouraged to deploy consistent community + handling across their networks, taking the inconsistent behaviors + from the various bgp implementations they operate into consideration. + Also, bgp implementors are expected to not create any further + inconsistencies from this point forward. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to be interpreted as described in RFC 2119 [RFC2119] only when they appear in all upper case. They may also appear in lower or mixed case as English words, without normative meaning. Status of This Memo @@ -35,25 +38,25 @@ 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 https://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 19, 2019. + This Internet-Draft will expire on July 11, 2019. Copyright Notice - Copyright (c) 2018 IETF Trust and the persons identified as the + Copyright (c) 2019 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 (https://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 @@ -71,22 +74,22 @@ 6. Action Items . . . . . . . . . . . . . . . . . . . . . . . . 5 7. Security Considerations . . . . . . . . . . . . . . . . . . . 5 8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5 9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5 10. Normative References . . . . . . . . . . . . . . . . . . . . 5 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6 1. Introduction The BGP Communities Attribute was specified in [RFC1997] which - introduced the concept of Well-Known Communities. In hindsight, it - did not prescribe as fully as it should have how Well-Known + introduced the concept of Well-Known Communities. In hindsight, + [RFC1997] did not prescribe as fully as it should have how Well-Known Communities may be manipulated by policies applied by operators. Currently, implementations differ in this regard, and these differences can result in inconsistent behaviors that operators find difficult to identify and resolve. This document describes the current behavioral differences in order to assist operators in generating consistent community-manipulation policies in a multi-vendor environment, and to prevent the introduction of additional divergence in implementations. @@ -153,21 +156,21 @@ Operators are advised to consult IOS-XR documentation and/or Cisco Systems support for full details. On Brocade NetIron: "set community X" removes all communities and sets X. In Huawei's VRP product, "community set" removes all received communities, well-Known or otherwise. In OpenBSD's OpenBGPD, "set community" does not remove any - communities, well-Known or otherwise. + communities, Well-Known or otherwise. 4.1. Note on an Inconsistency The IANA publishes a list of Well-Known Communities [IANA-WKS]. IOS-XR's set of well-known communities that "set community" will not overwrite diverges from IANA's list. Quite a few well-known communities from IANA's list do not receive special treatment in IOS- XR, and at least one specific community on IOS-XR's special treatment list (internet == 0:0) is not really on IANA's list -- it's taken @@ -184,23 +187,30 @@ 6. Action Items Unfortunately, it would be operationally disruptive for vendors to change their current implementations. Vendors SHOULD share the behavior of their implementations for inclusion in this document, especially if their behavior differs from the examples described. - For new well-known communities specified (after this draft), vendors - MUST treat "community set" command to mean "remove all other - communities, Well-Known or otherwise." + Vendors MUST ensure that any well-known communities specified after + this document's publication are removed by the "community set" + action. + + Given the implementation inconsistencies described in this document, + network operators are urged never to rely on any implicit + understanding of a neighbor ASN's bgp community handling. I.e., + before announcing prefixes with NO_EXPORT or any other community to a + neighbor ASN, the operator should confirm with that neighbor how the + community will be treated. 7. Security Considerations Surprising defaults and/or undocumented behaviors are not good for security. This document attempts to remedy that. 8. IANA Considerations This document has no IANA Considerations other than to be aware that any future Well-Known Communities will be subject to the policy