--- 1/draft-ietf-idr-bgp-open-policy-11.txt 2020-07-03 07:13:15.841226752 -0700 +++ 2/draft-ietf-idr-bgp-open-policy-12.txt 2020-07-03 07:13:15.877227669 -0700 @@ -1,41 +1,42 @@ Network Working Group A. Azimov -Internet-Draft E. Bogomazov -Intended status: Standards Track Qrator Labs -Expires: December 18, 2020 R. Bush +Internet-Draft Qrator Labs & Yandex +Intended status: Standards Track E. Bogomazov +Expires: January 4, 2021 Qrator Labs + R. Bush Internet Initiative Japan & Arrcus, Inc. K. Patel Arrcus K. Sriram USA NIST - June 16, 2020 + July 3, 2020 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 Route leaks are the propagation of BGP prefixes which violate assumptions of BGP topology relationships; e.g. passing a route learned from one lateral peer to another lateral peer or a transit provider, passing a route learned from one transit provider to another transit provider or a lateral peer. Existing approaches to leak prevention rely on marking routes by operator configuration, with no check that the configuration corresponds to that of the eBGP neighbor, or enforcement that the two eBGP speakers agree on the relationship. This document enhances BGP OPEN to establish agreement of the (peer, customer, provider, Route Server, Route Server client) relationship of two neighboring eBGP speakers to enforce appropriate configuration on both sides. Propagated routes are then marked with - an OTC attribute according to the agreed relationship, allowing both - prevention and detection of route leaks. + an Only to Customer (OTC) attribute according to the agreed + relationship, allowing both prevention and detection of route leaks. Requirements Language The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT", "SHOULD", "SHOULD NOT", "RECOMMENDED", "NOT RECOMMENDED", "MAY", and "OPTIONAL" in this document are to be interpreted as described in BCP 14 [RFC2119] [RFC8174] when, and only when, they appear in all capitals, as shown here. Status of This Memo @@ -46,21 +47,21 @@ 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 December 18, 2020. + This Internet-Draft will expire on January 4, 2021. Copyright Notice Copyright (c) 2020 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 @@ -68,61 +69,61 @@ 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 described in the Simplified BSD License. Table of Contents 1. Introduction . . . . . . . . . . . . . . . . . . . . . . . . 3 2. Peering Relationships . . . . . . . . . . . . . . . . . . . . 3 3. BGP Role . . . . . . . . . . . . . . . . . . . . . . . . . . 4 - 4. BGP Role Capability . . . . . . . . . . . . . . . . . . . . . 4 + 4. BGP Role Capability . . . . . . . . . . . . . . . . . . . . . 5 5. Role correctness . . . . . . . . . . . . . . . . . . . . . . 5 5.1. Strict mode . . . . . . . . . . . . . . . . . . . . . . . 6 6. BGP Only to Customer (OTC) Attribute . . . . . . . . . . . . 6 7. Enforcement . . . . . . . . . . . . . . . . . . . . . . . . . 7 8. Additional Considerations . . . . . . . . . . . . . . . . . . 7 9. IANA Considerations . . . . . . . . . . . . . . . . . . . . . 8 10. Security Considerations . . . . . . . . . . . . . . . . . . . 8 - 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 8 - 11.1. Normative References . . . . . . . . . . . . . . . . . . 8 + 11. References . . . . . . . . . . . . . . . . . . . . . . . . . 9 + 11.1. Normative References . . . . . . . . . . . . . . . . . . 9 11.2. Informative References . . . . . . . . . . . . . . . . . 9 Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . . 10 Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . 10 Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . 10 1. Introduction A BGP route leak occurs when a route is learned from a transit provider or lateral peer and then announced to another provider or lateral peer. See [RFC7908]. These are usually the result of misconfigured or absent BGP route filtering or lack of coordination between two eBGP speakers. The mechanism proposed in [I-D.ietf-grow-route-leak-detection-mitigation] uses large- communities to perform detection and mitigation of route leaks. While signaling using communities is easy to implement and deploy quickly, it normally relies on operator-maintained policy - configuration, which is often vulnerable to misconfiguration and even - attack [Streibelt]. There is also the vulnerability that the - community signal may be stripped, accidentally or maliciously. + configuration, which is vulnerable to misconfiguration [Streibelt]. + The community signal can also be stripped at the ISP boundaries. This document provides configuration automation using 'BGP roles', which are negotiated using a new BGP Capability Code in OPEN message (see Section 4 in [RFC5492]). Either or both BGP speakers MAY be configured to require that this capability be agreed for the BGP OPEN to succeed. - A new BGP Path Attribute is specified that SHOULD be automatically - configured using BGP roles. This attribute prevents networks from - creating leaks, and detects leaks created by third parties. + A new optional, transitive BGP Path Attribute Only to Customer (OTC) + is specified that SHOULD be automatically configured using BGP roles. + 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 "lateral peer" for simplicity. 2. Peering Relationships Despite the use of terms such as "customer", "peer", etc. in this document, these are not necessarily business relationships based on payment agreements. These terms are used to represent restrictions on BGP route propagation, sometimes known as the Gao-Rexford model @@ -154,24 +155,25 @@ routes they accept. Violation of the above rules may result in route leaks and MUST not be allowed. Automatic enforcement of these rules should significantly reduce route leaks that may otherwise occur due to manual configuration mistakes. While enforcing the above rules will address most BGP peering scenarios, their configuration is not part of BGP itself; therefore, configuration of ingress and egress prefix filters is still strongly advised. 3. BGP Role - BGP Role is a new configuration option that SHOULD be configured on - each eBGP session between ISPs that carry IPv4 and(or) IPv6 unicast - prefixes. It reflects the real-world agreement between two BGP - speakers about their relationship. + BGP Role is a new configuration option that can be configured on any + BGP session. BGP Roles reflect the agreement between two BGP + speakers about their relationship. One of the Roles described below + 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: o Provider - sender is a transit provider to neighbor; o Customer - sender is a transit customer of neighbor; o RS - sender is a Route Server, usually at an Internet exchange point (IX); @@ -209,21 +212,21 @@ eBGP speakers. But the mere presence of BGP Role doesn't automatically guarantee role agreement between two BGP peers. To enforce correctness, the BGP Role check is applied with a set of constraints on how speakers' BGP Roles MUST correspond. Of course, each speaker MUST announce and accept the BGP Role capability in the BGP OPEN message exchange. 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 - Role. The allowed pairings are as follow: + Role. The allowed pairings are as follows: +---------------+-----------------+ | Sender's Role | Receiver's Role | +---------------+-----------------+ | Provider | Customer | | Customer | Provider | | RS | RS-client | | RS-client | RS | | Peer | Peer | +---------------+-----------------+ @@ -236,31 +239,32 @@ eBGP connection, send a Role Mismatch Notification (code 2, subcode ), and also send a Connection Rejected Notification [RFC4486] (Notification with error code 6, subcode 5). 5.1. Strict mode 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 establish a BGP session with a neighbor which does not announce the BGP Role capability in the OPEN message. If a speaker rejects a - connection, it MUST send a Connection Rejected Notification [RFC4486] - (Notification with error code 6, subcode 5). By default, strict mode - SHOULD be set to false for backward compatibility with BGP speakers - that do not yet support this mechanism. + connection, it MUST send a send a Role Mismatch Notification (code 2, + subcode ), and also send a Connection Rejected Notification + [RFC4486] (Notification with error code 6, subcode 5). By default, + 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 Newly defined here, the Only to Customer (OTC) is an optional, 4 bytes long, transitive BGP Path attribute with the Type Code . - The purpose of this attribute is to guarantee that once route is sent - to customer, peer, or RS-client, it will subsequently go only to + The purpose of this attribute is to guarantee that once a route is + 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 described below. The semantics and usage of the OTC attribute are made clear by the ingress and egress policies described below. The following ingress policy applies to the OTC attribute: 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. 2. If a route with OTC attribute is received from a Peer and its @@ -283,25 +287,25 @@ Once the OTC attribute has been set, it MUST be preserved unchanged. 7. Enforcement Having the relationship unequivocally agreed between the two peers in BGP OPEN is critical; BGP implementations MUST enforce the relationship/role establishment rules (see Section 5) in order to ameliorate operator policy configuration errors (if any). 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. 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 marking. Hence, this document specifies OTC as an attribute. 8. Additional Considerations There are peering relationships that are 'complex', i.e., both parties are intentionally sending prefixes received from each other to their non-transit peers and/or transit providers. If multiple BGP peerings can segregate the 'complex' parts of the relationship, the complex peering roles can be segregated into different normal BGP @@ -402,22 +406,22 @@ [Gao] Gao, L. and J. Rexford, "Stable Internet routing without global coordination", IEEE/ACM Transactions on Networking, Volume 9, Issue 6, pp 689-692, DOI 10.1109/90.974523, December 2001, . [I-D.ietf-grow-route-leak-detection-mitigation] Sriram, K. and A. Azimov, "Methods for Detection and Mitigation of BGP Route Leaks", draft-ietf-grow-route- - leak-detection-mitigation-01 (work in progress), July - 2019. + leak-detection-mitigation-02 (work in progress), January + 2020. [RFC5226] Narten, T. and H. Alvestrand, "Guidelines for Writing an IANA Considerations Section in RFCs", RFC 5226, DOI 10.17487/RFC5226, May 2008, . [RFC7908] Sriram, K., Montgomery, D., McPherson, D., Osterweil, E., and B. Dickson, "Problem Definition and Classification of BGP Route Leaks", RFC 7908, DOI 10.17487/RFC7908, June 2016, . @@ -446,34 +450,34 @@ Independent Email: brian.peter.dickson@gmail.com Doug Montgomery USA National Institute of Standards and Technology Email: dougm@nist.gov Authors' Addresses Alexander Azimov - Qrator Labs - 1-y Magistralnyy tupik 5A - Moscow 123290 + Qrator Labs & Yandex + Ulitsa Lva Tolstogo 16 + Moscow 119021 Russian Federation Email: a.e.azimov@gmail.com - Eugene Bogomazov Qrator Labs 1-y Magistralnyy tupik 5A Moscow 123290 Russian Federation Email: eb@qrator.net + Randy Bush Internet Initiative Japan & Arrcus, Inc. 5147 Crystal Springs Bainbridge Island, Washington 98110 United States of America Email: randy@psg.com Keyur Patel Arrcus