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
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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
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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.
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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
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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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