draft-ietf-grow-wkc-behavior-00.txt		draft-ietf-grow-wkc-behavior-01.txt
	Network Working Group J. Borkenhagen		Network Working Group J. Borkenhagen
	Internet-Draft AT&T		Internet-Draft AT&T
	Intended status: Standards Track R. Bush		Intended status: Standards Track R. Bush
	Expires: January 19, 2019 Internet Initiative Japan		Expires: July 11, 2019 Internet Initiative Japan
	R. Bonica		R. Bonica
	Juniper Networks		Juniper Networks
	S. Bayraktar		S. Bayraktar
	Cisco Systems		Cisco Systems
	July 18, 2018		January 7, 2019
	Well-Known Community Policy Behavior		Well-Known Community Policy Behavior
	draft-ietf-grow-wkc-behavior-00		draft-ietf-grow-wkc-behavior-01
	Abstract		Abstract
	Well-Known BGP Communities are manipulated inconsistently by current		Well-Known BGP Communities are manipulated inconsistently by current
	implementations. This results in difficulties for operators. It is		implementations. This results in difficulties for operators.
	recommended that removal policies be applied consistently to Well-		Network operators are encouraged to deploy consistent community
	Known Communities.		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		Requirements Language
	The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",		The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
	"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to		"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
	be interpreted as described in RFC 2119 [RFC2119] only when they		be interpreted as described in RFC 2119 [RFC2119] only when they
	appear in all upper case. They may also appear in lower or mixed		appear in all upper case. They may also appear in lower or mixed
	case as English words, without normative meaning.		case as English words, without normative meaning.
	Status of This Memo		Status of This Memo
	skipping to change at page 1, line 46 ¶		skipping to change at page 1, line 49 ¶
	Internet-Drafts are working documents of the Internet Engineering		Internet-Drafts are working documents of the Internet Engineering
	Task Force (IETF). Note that other groups may also distribute		Task Force (IETF). Note that other groups may also distribute
	working documents as Internet-Drafts. The list of current Internet-		working documents as Internet-Drafts. The list of current Internet-
	Drafts is at https://datatracker.ietf.org/drafts/current/.		Drafts is at https://datatracker.ietf.org/drafts/current/.
	Internet-Drafts are draft documents valid for a maximum of six months		Internet-Drafts are draft documents valid for a maximum of six months
	and may be updated, replaced, or obsoleted by other documents at any		and may be updated, replaced, or obsoleted by other documents at any
	time. It is inappropriate to use Internet-Drafts as reference		time. It is inappropriate to use Internet-Drafts as reference
	material or to cite them other than as "work in progress."		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 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.		document authors. All rights reserved.
	This document is subject to BCP 78 and the IETF Trust's Legal		This document is subject to BCP 78 and the IETF Trust's Legal
	Provisions Relating to IETF Documents		Provisions Relating to IETF Documents
	(https://trustee.ietf.org/license-info) in effect on the date of		(https://trustee.ietf.org/license-info) in effect on the date of
	publication of this document. Please review these documents		publication of this document. Please review these documents
	carefully, as they describe your rights and restrictions with respect		carefully, as they describe your rights and restrictions with respect
	to this document. Code Components extracted from this document must		to this document. Code Components extracted from this document must
	include Simplified BSD License text as described in Section 4.e of		include Simplified BSD License text as described in Section 4.e of
	the Trust Legal Provisions and are provided without warranty as		the Trust Legal Provisions and are provided without warranty as
	skipping to change at page 2, line 39 ¶		skipping to change at page 2, line 39 ¶
	6. Action Items . . . . . . . . . . . . . . . . . . . . . . . . 5		6. Action Items . . . . . . . . . . . . . . . . . . . . . . . . 5
	7. Security Considerations . . . . . . . . . . . . . . . . . . . 5		7. Security Considerations . . . . . . . . . . . . . . . . . . . 5
	8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5		8. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 5
	9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5		9. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . 5
	10. Normative References . . . . . . . . . . . . . . . . . . . . 5		10. Normative References . . . . . . . . . . . . . . . . . . . . 5
	Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6		Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 6
	1. Introduction		1. Introduction
	The BGP Communities Attribute was specified in [RFC1997] which		The BGP Communities Attribute was specified in [RFC1997] which
	introduced the concept of Well-Known Communities. In hindsight, it		introduced the concept of Well-Known Communities. In hindsight,
	did not prescribe as fully as it should have how Well-Known		[RFC1997] did not prescribe as fully as it should have how Well-Known
	Communities may be manipulated by policies applied by operators.		Communities may be manipulated by policies applied by operators.
	Currently, implementations differ in this regard, and these		Currently, implementations differ in this regard, and these
	differences can result in inconsistent behaviors that operators find		differences can result in inconsistent behaviors that operators find
	difficult to identify and resolve.		difficult to identify and resolve.
	This document describes the current behavioral differences in order		This document describes the current behavioral differences in order
	to assist operators in generating consistent community-manipulation		to assist operators in generating consistent community-manipulation
	policies in a multi-vendor environment, and to prevent the		policies in a multi-vendor environment, and to prevent the
	introduction of additional divergence in implementations.		introduction of additional divergence in implementations.
	skipping to change at page 4, line 32 ¶		skipping to change at page 4, line 32 ¶
	Operators are advised to consult IOS-XR documentation and/or Cisco		Operators are advised to consult IOS-XR documentation and/or Cisco
	Systems support for full details.		Systems support for full details.
	On Brocade NetIron: "set community X" removes all communities and		On Brocade NetIron: "set community X" removes all communities and
	sets X.		sets X.
	In Huawei's VRP product, "community set" removes all received		In Huawei's VRP product, "community set" removes all received
	communities, well-Known or otherwise.		communities, well-Known or otherwise.
	In OpenBSD's OpenBGPD, "set community" does not remove any		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		4.1. Note on an Inconsistency
	The IANA publishes a list of Well-Known Communities [IANA-WKS].		The IANA publishes a list of Well-Known Communities [IANA-WKS].
	IOS-XR's set of well-known communities that "set community" will not		IOS-XR's set of well-known communities that "set community" will not
	overwrite diverges from IANA's list. Quite a few well-known		overwrite diverges from IANA's list. Quite a few well-known
	communities from IANA's list do not receive special treatment in IOS-		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		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		list (internet == 0:0) is not really on IANA's list -- it's taken
	skipping to change at page 5, line 14 ¶		skipping to change at page 5, line 14 ¶
	6. Action Items		6. Action Items
	Unfortunately, it would be operationally disruptive for vendors to		Unfortunately, it would be operationally disruptive for vendors to
	change their current implementations.		change their current implementations.
	Vendors SHOULD share the behavior of their implementations for		Vendors SHOULD share the behavior of their implementations for
	inclusion in this document, especially if their behavior differs from		inclusion in this document, especially if their behavior differs from
	the examples described.		the examples described.
	For new well-known communities specified (after this draft), vendors		Vendors MUST ensure that any well-known communities specified after
	MUST treat "community set" command to mean "remove all other		this document's publication are removed by the "community set"
	communities, Well-Known or otherwise."		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		7. Security Considerations
	Surprising defaults and/or undocumented behaviors are not good for		Surprising defaults and/or undocumented behaviors are not good for
	security. This document attempts to remedy that.		security. This document attempts to remedy that.
	8. IANA Considerations		8. IANA Considerations
	This document has no IANA Considerations other than to be aware that		This document has no IANA Considerations other than to be aware that
	any future Well-Known Communities will be subject to the policy		any future Well-Known Communities will be subject to the policy
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