draft-ietf-idr-bgp-open-policy-11.txt   draft-ietf-idr-bgp-open-policy-12.txt 
Network Working Group A. Azimov Network Working Group A. Azimov
Internet-Draft E. Bogomazov Internet-Draft Qrator Labs & Yandex
Intended status: Standards Track Qrator Labs Intended status: Standards Track E. Bogomazov
Expires: December 18, 2020 R. Bush Expires: January 4, 2021 Qrator Labs
R. Bush
Internet Initiative Japan & Arrcus, Inc. Internet Initiative Japan & Arrcus, Inc.
K. Patel K. Patel
Arrcus Arrcus
K. Sriram K. Sriram
USA NIST USA NIST
June 16, 2020 July 3, 2020
Route Leak Prevention using Roles in Update and Open messages Route Leak Prevention using Roles in Update and Open messages
draft-ietf-idr-bgp-open-policy-11 draft-ietf-idr-bgp-open-policy-12
Abstract Abstract
Route leaks are the propagation of BGP prefixes which violate Route leaks are the propagation of BGP prefixes which violate
assumptions of BGP topology relationships; e.g. passing a route assumptions of BGP topology relationships; e.g. passing a route
learned from one lateral peer to another lateral peer or a transit learned from one lateral peer to another lateral peer or a transit
provider, passing a route learned from one transit provider to provider, passing a route learned from one transit provider to
another transit provider or a lateral peer. Existing approaches to another transit provider or a lateral peer. Existing approaches to
leak prevention rely on marking routes by operator configuration, leak prevention rely on marking routes by operator configuration,
with no check that the configuration corresponds to that of the eBGP with no check that the configuration corresponds to that of the eBGP
neighbor, or enforcement that the two eBGP speakers agree on the neighbor, or enforcement that the two eBGP speakers agree on the
relationship. This document enhances BGP OPEN to establish agreement relationship. This document enhances BGP OPEN to establish agreement
of the (peer, customer, provider, Route Server, Route Server client) of the (peer, customer, provider, Route Server, Route Server client)
relationship of two neighboring eBGP speakers to enforce appropriate relationship of two neighboring eBGP speakers to enforce appropriate
configuration on both sides. Propagated routes are then marked with configuration on both sides. Propagated routes are then marked with
an OTC attribute according to the agreed relationship, allowing both an Only to Customer (OTC) attribute according to the agreed
prevention and detection of route leaks. relationship, allowing both prevention and detection of route leaks.
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", "NOT RECOMMENDED", "MAY", and "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and
"OPTIONAL" in this document are to be interpreted as described in "OPTIONAL" in this document are to be interpreted as described in
BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all
capitals, as shown here. capitals, as shown here.
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 December 18, 2020. This Internet-Draft will expire on January 4, 2021.
Copyright Notice Copyright Notice
Copyright (c) 2020 IETF Trust and the persons identified as the Copyright (c) 2020 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
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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
described in the Simplified BSD License. described in the Simplified BSD License.
Table of Contents Table of Contents
1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3
2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 3 2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 3
3. BGP Role . . . . . . . . . . . . . . . . . . . . . . . . . . 4 3. BGP Role . . . . . . . . . . . . . . . . . . . . . . . . . . 4
4. BGP Role Capability . . . . . . . . . . . . . . . . . . . . . 4 4. BGP Role Capability . . . . . . . . . . . . . . . . . . . . . 5
5. Role correctness . . . . . . . . . . . . . . . . . . . . . . 5 5. Role correctness . . . . . . . . . . . . . . . . . . . . . . 5
5.1. Strict mode . . . . . . . . . . . . . . . . . . . . . . . 6 5.1. Strict mode . . . . . . . . . . . . . . . . . . . . . . . 6
6. BGP Only to Customer (OTC) Attribute . . . . . . . . . . . . 6 6. BGP Only to Customer (OTC) Attribute . . . . . . . . . . . . 6
7. Enforcement . . . . . . . . . . . . . . . . . . . . . . . . . 7 7. Enforcement . . . . . . . . . . . . . . . . . . . . . . . . . 7
8. Additional Considerations . . . . . . . . . . . . . . . . . . 7 8. Additional Considerations . . . . . . . . . . . . . . . . . . 7
9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8
10. Security Considerations . . . . . . . . . . . . . . . . . . . 8 10. Security Considerations . . . . . . . . . . . . . . . . . . . 8
11. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 9
11.1. Normative References . . . . . . . . . . . . . . . . . . 8 11.1. Normative References . . . . . . . . . . . . . . . . . . 9
11.2. Informative References . . . . . . . . . . . . . . . . . 9 11.2. Informative References . . . . . . . . . . . . . . . . . 9
Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10
Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10
1. Introduction 1. Introduction
A BGP route leak occurs when a route is learned from a transit A BGP route leak occurs when a route is learned from a transit
provider or lateral peer and then announced to another provider or provider or lateral peer and then announced to another provider or
lateral peer. See [RFC7908]. These are usually the result of lateral peer. See [RFC7908]. These are usually the result of
misconfigured or absent BGP route filtering or lack of coordination misconfigured or absent BGP route filtering or lack of coordination
between two eBGP speakers. between two eBGP speakers.
The mechanism proposed in The mechanism proposed in
[I-D.ietf-grow-route-leak-detection-mitigation] uses large- [I-D.ietf-grow-route-leak-detection-mitigation] uses large-
communities to perform detection and mitigation of route leaks. communities to perform detection and mitigation of route leaks.
While signaling using communities is easy to implement and deploy While signaling using communities is easy to implement and deploy
quickly, it normally relies on operator-maintained policy quickly, it normally relies on operator-maintained policy
configuration, which is often vulnerable to misconfiguration and even configuration, which is vulnerable to misconfiguration [Streibelt].
attack [Streibelt]. There is also the vulnerability that the The community signal can also be stripped at the ISP boundaries.
community signal may be stripped, accidentally or maliciously.
This document provides configuration automation using 'BGP roles', This document provides configuration automation using 'BGP roles',
which are negotiated using a new BGP Capability Code in OPEN message which are negotiated using a new BGP Capability Code in OPEN message
(see Section 4 in [RFC5492]). Either or both BGP speakers MAY be (see Section 4 in [RFC5492]). Either or both BGP speakers MAY be
configured to require that this capability be agreed for the BGP OPEN configured to require that this capability be agreed for the BGP OPEN
to succeed. to succeed.
A new BGP Path Attribute is specified that SHOULD be automatically A new optional, transitive BGP Path Attribute Only to Customer (OTC)
configured using BGP roles. This attribute prevents networks from is specified that SHOULD be automatically configured using BGP roles.
creating leaks, and detects leaks created by third parties. This attribute prevents networks from creating leaks, and detects
leaks created by third parties.
In the rest of this document, we use the term "peer" to refer to In the rest of this document, we use the term "peer" to refer to
"lateral peer" for simplicity. "lateral peer" for simplicity.
2. Peering Relationships 2. Peering Relationships
Despite the use of terms such as "customer", "peer", etc. in this Despite the use of terms such as "customer", "peer", etc. in this
document, these are not necessarily business relationships based on document, these are not necessarily business relationships based on
payment agreements. These terms are used to represent restrictions payment agreements. These terms are used to represent restrictions
on BGP route propagation, sometimes known as the Gao-Rexford model on BGP route propagation, sometimes known as the Gao-Rexford model
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routes they accept. Violation of the above rules may result in route routes they accept. Violation of the above rules may result in route
leaks and MUST not be allowed. Automatic enforcement of these rules leaks and MUST not be allowed. Automatic enforcement of these rules
should significantly reduce route leaks that may otherwise occur due should significantly reduce route leaks that may otherwise occur due
to manual configuration mistakes. While enforcing the above rules to manual configuration mistakes. While enforcing the above rules
will address most BGP peering scenarios, their configuration is not will address most BGP peering scenarios, their configuration is not
part of BGP itself; therefore, configuration of ingress and egress part of BGP itself; therefore, configuration of ingress and egress
prefix filters is still strongly advised. prefix filters is still strongly advised.
3. BGP Role 3. BGP Role
BGP Role is a new configuration option that SHOULD be configured on BGP Role is a new configuration option that can be configured on any
each eBGP session between ISPs that carry IPv4 and(or) IPv6 unicast BGP session. BGP Roles reflect the agreement between two BGP
prefixes. It reflects the real-world agreement between two BGP speakers about their relationship. One of the Roles described below
speakers about their relationship. SHOULD be configured on each eBGP session between ISPs that carry
IPv4 and(or) IPv6 unicast prefixes.
Allowed Role values for eBGP sessions between ISPs are: Allowed Role values for eBGP sessions between ISPs are:
o Provider - sender is a transit provider to neighbor; o Provider - sender is a transit provider to neighbor;
o Customer - sender is a transit customer of neighbor; o Customer - sender is a transit customer of neighbor;
o RS - sender is a Route Server, usually at an Internet exchange o RS - sender is a Route Server, usually at an Internet exchange
point (IX); point (IX);
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eBGP speakers. But the mere presence of BGP Role doesn't eBGP speakers. But the mere presence of BGP Role doesn't
automatically guarantee role agreement between two BGP peers. automatically guarantee role agreement between two BGP peers.
To enforce correctness, the BGP Role check is applied with a set of To enforce correctness, the BGP Role check is applied with a set of
constraints on how speakers' BGP Roles MUST correspond. Of course, constraints on how speakers' BGP Roles MUST correspond. Of course,
each speaker MUST announce and accept the BGP Role capability in the each speaker MUST announce and accept the BGP Role capability in the
BGP OPEN message exchange. BGP OPEN message exchange.
If a speaker receives a BGP Role capability, it MUST check the value If a speaker receives a BGP Role capability, it MUST check the value
of the received capability (i.e., the sender's role) with its own BGP of the received capability (i.e., the sender's role) with its own BGP
Role. The allowed pairings are as follow: Role. The allowed pairings are as follows:
+---------------+-----------------+ +---------------+-----------------+
| Sender's Role | Receiver's Role | | Sender's Role | Receiver's Role |
+---------------+-----------------+ +---------------+-----------------+
| Provider | Customer | | Provider | Customer |
| Customer | Provider | | Customer | Provider |
| RS | RS-client | | RS | RS-client |
| RS-client | RS | | RS-client | RS |
| Peer | Peer | | Peer | Peer |
+---------------+-----------------+ +---------------+-----------------+
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eBGP connection, send a Role Mismatch Notification (code 2, subcode eBGP connection, send a Role Mismatch Notification (code 2, subcode
<TBD2>), and also send a Connection Rejected Notification [RFC4486] <TBD2>), and also send a Connection Rejected Notification [RFC4486]
(Notification with error code 6, subcode 5). (Notification with error code 6, subcode 5).
5.1. Strict mode 5.1. Strict mode
A new BGP configuration option "strict mode" is defined with values A new BGP configuration option "strict mode" is defined with values
of true or false. If set to true, then the speaker MUST refuse to of true or false. If set to true, then the speaker MUST refuse to
establish a BGP session with a neighbor which does not announce the establish a BGP session with a neighbor which does not announce the
BGP Role capability in the OPEN message. If a speaker rejects a BGP Role capability in the OPEN message. If a speaker rejects a
connection, it MUST send a Connection Rejected Notification [RFC4486] connection, it MUST send a send a Role Mismatch Notification (code 2,
(Notification with error code 6, subcode 5). By default, strict mode subcode <TBD2>), and also send a Connection Rejected Notification
SHOULD be set to false for backward compatibility with BGP speakers [RFC4486] (Notification with error code 6, subcode 5). By default,
that do not yet support this mechanism. strict mode SHOULD be set to false for backward compatibility with
BGP speakers that do not yet support this mechanism.
6. BGP Only to Customer (OTC) Attribute 6. BGP Only to Customer (OTC) Attribute
Newly defined here, the Only to Customer (OTC) is an optional, 4 Newly defined here, the Only to Customer (OTC) is an optional, 4
bytes long, transitive BGP Path attribute with the Type Code <TBD3>. bytes long, transitive BGP Path attribute with the Type Code <TBD3>.
The purpose of this attribute is to guarantee that once route is sent The purpose of this attribute is to guarantee that once a route is
to customer, peer, or RS-client, it will subsequently go only to sent to customer, peer, or RS-client, it will subsequently go only to
customers. The value of OTC is an AS number determined by policy as customers. The value of OTC is an AS number determined by policy as
described below. The semantics and usage of the OTC attribute are described below. The semantics and usage of the OTC attribute are
made clear by the ingress and egress policies described below. made clear by the ingress and egress policies described below.
The following ingress policy applies to the OTC attribute: The following ingress policy applies to the OTC attribute:
1. If a route with OTC attribute is received from a Customer or RS- 1. If a route with OTC attribute is received from a Customer or RS-
client, then it is a route leak and MUST be rejected. client, then it is a route leak and MUST be rejected.
2. If a route with OTC attribute is received from a Peer and its 2. If a route with OTC attribute is received from a Peer and its
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Once the OTC attribute has been set, it MUST be preserved unchanged. Once the OTC attribute has been set, it MUST be preserved unchanged.
7. Enforcement 7. Enforcement
Having the relationship unequivocally agreed between the two peers in Having the relationship unequivocally agreed between the two peers in
BGP OPEN is critical; BGP implementations MUST enforce the BGP OPEN is critical; BGP implementations MUST enforce the
relationship/role establishment rules (see Section 5) in order to relationship/role establishment rules (see Section 5) in order to
ameliorate operator policy configuration errors (if any). ameliorate operator policy configuration errors (if any).
Similarly, the application of that relationship on prefix propagation Similarly, the application of that relationship on prefix propagation
using OTC MUST BE enforced by the BGP implementations, and not using OTC MUST be enforced by the BGP implementations, and not
exposed to user misconfiguration. exposed to user misconfiguration.
As opposed to communities, BGP attributes may not be generally As opposed to communities, BGP attributes may not be generally
modified or filtered by the operator; BGP router implementations modified or stripped by the operator; BGP router implementations
enforce such treatment. This is the desired property for the OTC enforce such treatment. This is the desired property for the OTC
marking. Hence, this document specifies OTC as an attribute. marking. Hence, this document specifies OTC as an attribute.
8. Additional Considerations 8. Additional Considerations
There are peering relationships that are 'complex', i.e., both There are peering relationships that are 'complex', i.e., both
parties are intentionally sending prefixes received from each other parties are intentionally sending prefixes received from each other
to their non-transit peers and/or transit providers. If multiple BGP to their non-transit peers and/or transit providers. If multiple BGP
peerings can segregate the 'complex' parts of the relationship, the peerings can segregate the 'complex' parts of the relationship, the
complex peering roles can be segregated into different normal BGP complex peering roles can be segregated into different normal BGP
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[Gao] Gao, L. and J. Rexford, "Stable Internet routing without [Gao] Gao, L. and J. Rexford, "Stable Internet routing without
global coordination", IEEE/ACM Transactions on global coordination", IEEE/ACM Transactions on
Networking, Volume 9, Issue 6, pp 689-692, DOI Networking, Volume 9, Issue 6, pp 689-692, DOI
10.1109/90.974523, December 2001, 10.1109/90.974523, December 2001,
<https://ieeexplore.ieee.org/document/974523>. <https://ieeexplore.ieee.org/document/974523>.
[I-D.ietf-grow-route-leak-detection-mitigation] [I-D.ietf-grow-route-leak-detection-mitigation]
Sriram, K. and A. Azimov, "Methods for Detection and Sriram, K. and A. Azimov, "Methods for Detection and
Mitigation of BGP Route Leaks", draft-ietf-grow-route- Mitigation of BGP Route Leaks", draft-ietf-grow-route-
leak-detection-mitigation-01 (work in progress), July leak-detection-mitigation-02 (work in progress), January
2019. 2020.
[RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an
IANA Considerations Section in RFCs", RFC 5226, IANA Considerations Section in RFCs", RFC 5226,
DOI 10.17487/RFC5226, May 2008, DOI 10.17487/RFC5226, May 2008,
<https://www.rfc-editor.org/info/rfc5226>. <https://www.rfc-editor.org/info/rfc5226>.
[RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E., [RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E.,
and B. Dickson, "Problem Definition and Classification of and B. Dickson, "Problem Definition and Classification of
BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June
2016, <https://www.rfc-editor.org/info/rfc7908>. 2016, <https://www.rfc-editor.org/info/rfc7908>.
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Independent Independent
Email: brian.peter.dickson@gmail.com Email: brian.peter.dickson@gmail.com
Doug Montgomery Doug Montgomery
USA National Institute of Standards and Technology USA National Institute of Standards and Technology
Email: dougm@nist.gov Email: dougm@nist.gov
Authors' Addresses Authors' Addresses
Alexander Azimov Alexander Azimov
Qrator Labs Qrator Labs & Yandex
1-y Magistralnyy tupik 5A Ulitsa Lva Tolstogo 16
Moscow 123290 Moscow 119021
Russian Federation Russian Federation
Email: a.e.azimov@gmail.com Email: a.e.azimov@gmail.com
Eugene Bogomazov Eugene Bogomazov
Qrator Labs Qrator Labs
1-y Magistralnyy tupik 5A 1-y Magistralnyy tupik 5A
Moscow 123290 Moscow 123290
Russian Federation Russian Federation
Email: eb@qrator.net Email: eb@qrator.net
Randy Bush Randy Bush
Internet Initiative Japan & Arrcus, Inc. Internet Initiative Japan & Arrcus, Inc.
5147 Crystal Springs 5147 Crystal Springs
Bainbridge Island, Washington 98110 Bainbridge Island, Washington 98110
United States of America United States of America
Email: randy@psg.com Email: randy@psg.com
Keyur Patel Keyur Patel
Arrcus Arrcus
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