Internet DRAFT - draft-gu-grow-bmp-route-leak-detection

draft-gu-grow-bmp-route-leak-detection







Network Working Group                                              Y. Gu
Internet-Draft                                                    Huawei
Intended status: Standards Track                                 H. Chen
Expires: 4 September 2024                        China Telecom Co., Ltd.
                                                                   D. Ma
                                                                    ZDNS
                                                                 N. Geng
                                                               S. Zhuang
                                                                  Huawei
                                                            3 March 2024


                    BMP for BGP Route Leak Detection
               draft-gu-grow-bmp-route-leak-detection-06

Abstract

   According to Route-Leak Problem Definition [RFC7908], Route leaks
   refer to the case that the delivery range of route advertisements is
   beyond the expected range.  For many current security protection
   solutions, the ISPs (Internet Service Providers) are focusing on
   finding ways to prevent the happening of BGP [RFC4271] route leaks.
   However, the real-time route leak detection if any occurs is
   important as well, and serves as the basis for leak mitigation.  This
   document extends the BGP Monitoring Protocol (BMP) [RFC7854] to
   provide a routing security scheme suitable for ISPs to detect BGP
   route leaks at the prefix level.


Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in this
   document are to be interpreted as described in RFC 2119 [RFC2119].

Status of This Memo

   This Internet-Draft is submitted in full conformance with the
   provisions of BCP 78 and BCP 79.

   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/.







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   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 4 September 2024.

Copyright Notice

   Copyright (c) 2024 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
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   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Revised BSD License.

Table of Contents

   1.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   3
     2.1.  Actions Against Route Leaks . . . . . . . . . . . . . . .   3
     2.2.  Challenges of the Current Actions against Route Leaks . .   4
   3.  Route Leak Detection (RLD) Design Considerations  . . . . . .   5
   4.  BMP Support for RLD . . . . . . . . . . . . . . . . . . . . .   5
     4.1.  RLD TLV Format  . . . . . . . . . . . . . . . . . . . . .   6
     4.2.  RLD TLV Usage . . . . . . . . . . . . . . . . . . . . . .   7
     4.3.  Coordination with iOTC and RLP  . . . . . . . . . . . . .   8
   5.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   8
   6.  Contributors  . . . . . . . . . . . . . . . . . . . . . . . .   8
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   9
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   9
   9.  References  . . . . . . . . . . . . . . . . . . . . . . . . .   9
     9.1.  Normative References  . . . . . . . . . . . . . . . . . .   9
     9.2.  Informative References  . . . . . . . . . . . . . . . . .  10
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  10

1.  Terminology

   BMP: BGP Monitoring Protocol

   BMS: BGP Monitoring Station

   C2P: Customer to Provider



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   ISP: Internet Service Provider

   P2C: Provider to Customer

   P2P: Peer to Peer

   RIB: Routing Information Base

   RLP: Route Leak Protection

   RLD: Route Leak Detection

2.  Introduction

   RFC7908 [RFC7908] defines "Route Leak" as: A route leak is the
   propagation of routing announcement(s) beyond their intended scope,
   which can result in possible situations such as eavesdropping, device
   overload, routing black hole and so on.  More specifically, the
   intended scope of route announcements is usually defined by local
   route filtering/distribution policies within devices.  These policies
   are designed to realise the pair-wise peering business relationships
   between ASes (autonomous systems), which include Customer to Provider
   (C2P), Peer to Peer (Peer to Peer), and Provider to Customer (P2C).
   In a C2P relationship, the customer pays the transit provider for
   traffic sent between the two ASes.  In return, the customer gains
   access to the ASes that the transit provider can reach, including
   those which the transit provider reaches through its own transit
   providers.  In a P2P relationship, the peering ASes gain access to
   each other's customers, typically without either AS paying the other
   AS Relationships, Customer Cones, and Validation [Luckie].

   More precisely, the route leaks we discuss in this draft, referring
   to Type 1, 2, 3, and 4 Route Leaks defined in RFC7908 [RFC7908], can
   be summarized as: a route leak occurs when a route received from a
   transit provider or a lateral peer is propagated to another transit
   provider or a lateral peer.

2.1.  Actions Against Route Leaks

   There are several types of approaches against route leak from
   different perspectives.  In this draft, we mainly discuss the
   following three types:

   *  Route leak prevention: The approach to prevent route leak from
      happening.  Commonly used methods include inbound/outbound
      prefix/peer/AS filtering policies configured at the ingress/egress
      nodes of ASes per the propagation of BGP routes.




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   *  Route leak detection: The approach to detect the existence of
      route leaks that happen at either the local AS, or upstream AS per
      the propagation of BGP routes.  An intuitive way of detecting
      route leak is by checking the business relationship information at
      both the ingress and egress nodes of the local AS along the BGP
      route propagation path with the route leak violation rules defined
      in RFC7908 [RFC7908].  Thus, it requires the knowledge of the
      actual route propagation trace, as well as the resulting business
      relationship information at the ingress and egress nodes.  With
      the above information collected, the analysis can be done by the
      routing device or a centralized server.  This draft specifies one
      such method.

   *  Route leak mitigation: The approach to mitigate route leaks that
      already happened at either the local AS, or upstream AS per the
      propagation of BGP routes.  Commonly used methods include reject,
      drop or stop propagating the invalid routes once detected the
      existence of leaks.

   The above mentioned actions can be used alone or in combination,
   depending on the entities (routing devices, network manager) that
   execute the actions, and the relative positions of the executing
   entities from the leaking point (local or downstream).

2.2.  Challenges of the Current Actions against Route Leaks

   Route Leak Prevention [I-D.ietf-idr-bgp-open-policy] updates the BGP
   Open negotiation process with a new BGP capability to exchange the
   BGP Roles between two BGP speakers, and also proposes to use a new
   BGP attribute, called the iOTC (Internal Only To Customer) Path
   attribute to mark routes according to the BGP Roles established in
   Open Message.  The iOTC attribute of the incoming route is set at the
   ingress node of the local AS, and is conveyed with the BGP Update to
   the egress node of the local AS for outbound filtering to prevent
   route leaks in the local AS.  This attribute is removed at the egress
   node before the BGP Update is sent to eBGP neighbors.  For
   representation simplification, we use iOTC to refer to the method
   specified in Route Leak Prevention [I-D.ietf-idr-bgp-open-policy].













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   Route-Leak Detection and Mitigation
   [I-D.ietf-grow-route-leak-detection-mitigation] describes a route
   leak detection and mitigation solution based on conveying route-leak
   protection (RLP) information in a well-known transitive BGP
   community, called the RLP community.  The RLP community helps with
   detection and mitigation of route leaks that happen at the upstream
   AS (per the BGP routes propagation), as an Inter-AS solution.  For
   representation simplification, we use RLP to refer to the method
   specified in Route-Leak Detection and Mitigation
   [I-D.ietf-grow-route-leak-detection-mitigation].

   The above two drafts provide solutions for route leak prevention,
   detection and mitigation.  To summarize:

   *  iOTC is used for route leak prevention of the local AS.  It does
      not provide the detection or mitigation of route leaks of either
      local As or upstream AS per the BGP routes propagation.

   *  iOTC is peer/AS-level route leak prevention, due to the fact the
      BGP Role negotiation is peer-level.  It does not provide prefix-
      level route leak prevention.

   *  RLP is used for route leak detection and mitigation of route leak
      that happens in the upstream AS (per the BGP Update distribution).
      It is prefix-level detection and mitigation.

   Thus, there lacks method for local AS route leak detection.

3.  Route Leak Detection (RLD) Design Considerations

   Considering the challenges facing the existing approaches, this draft
   proposes a method called Route Leak Detection (RLD).  It utilizes the
   BGP Monitoring Protocol (BMP) to convey the RLD information from to
   the BMP server to realize centralized leak detection.  BMP is
   currently deployed by OTT and carriers to monitor the BGP routes,
   such as monitoring BGP Adj-RIB-In using the process defined in
   RFC7854 [RFC7854], and monitoring BGP Adj-RIB-Out using the process
   defined in RFC8671 [RFC8671].  On the other hand, the RLD information
   is in fact a representation of the business relationships between the
   local AS and its neighboring AS.  It does not involve any information
   disclosure issue regarding third parties.  Thus, a single ISP can
   deploy RLD without relying on any information from either other ISPs
   or other third parties.


4.  BMP Support for RLD





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4.1.  RLD TLV Format

   A RLD TLV is defined for the BMP Route Monitoring Message.
   Considering that the AS relationships are sometimes per route based
   instead of per peer/AS based, this TLV is appended to each route,
   following the BGP Update Message.  The order of placing the RLD TLV
   among other BMP supported TLVs is out of the scope of this draft.
   The TLV format is defined as follows:

    0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |      Type (2 octets)          |     Length (2 octets)         |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   | Value(1 octet)|
   +-+-+-+-+-+-+-+-+

                          Figure 1: RLD TLV

   *  Type (2 octets) = TBD1, the RLD TLV represents the prefix-level
      business relationship between the transmitter AS and the receiver
      AS.  The local AS is a transmitter or a receiver, depending on if
      the route is an incoming route from a neighbor AS or an outgoing
      route to a neighbor AS.

   *  Length (2 octets): Defines the length of the Value filed.  It
      SHOULD be set to 0x01, considering the Value field is of 1 octet
      fixed length.

   *  Value (1 octet): Currently 4 values are defined to represent the
      business relationships, which are specified in Table 1.

   +-------+-------------+
   | Value | Business    |
   |       | Relationship|
   +---------------------+
   |   0   |  P2C        |
   |   1   |  C2P        |
   |   2   |  P2P        |
   |   3   |  I2I        |
   +-------+-------------+

   Table 1: Business relationship value









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4.2.  RLD TLV Usage

   The RLD TLV, presenting the business relationship between the
   neighbor AS and the local AS of the incoming route, SHOULD be
   prepended to the Adj-RIB-In at the ingress node of the local AS.  The
   RLD TLV, representing the business relationship between the local AS
   and the neighbor AS of the outgoing route, SHOULD also be prepended
   to the Adj-RIB-Out at the egress node of the local AS.  The BMP
   server, by analyzing the above two RLD TLVs of the same route, can
   use the rules defined in RFC7908 [RFC7908] to detect the existence of
   any route leak.  As example is shown in Figure 2.

                               +------------+
                               | BMP server |
                        +------>      +     +<-------+
                        |      | RLD server |        |
                        +      +------------+        +
                BMP Adj_RIB_In:                 BMP Adj_RIB_Out:
                (AS2 --> AS1)                   (AS1 --> AS4)
                 P2C                            C2P
                        |                            +
                     ***|*********************       |
                     *  |                    *     "Send Route
      Route A        *  |       AS1         +*+---> A to AS3"
      +-->           *  |                  + *       |  +-----+
      +-----+        *  +---+         +---+  *+P2C+-----+ AS3 +----+ ...
   +--+ AS2 +---+P2C+*+-+ R1+---------+ R2|  *       |  +-----+
      +-----+        *  +-+-+\        +---+  *       |
                     *    |   \\    //  |\   *       |
                     *    |     \\//    | \  *     "Do not send
                     *    |     //\     |  \+-----> Route A to AS4"
                     *    |   //   \\   |    *       |  +-----+
                     *    |  /       \  |    *+C2P+-----+ AS4 +----+ ...
                     *  +-+-+         +-+-+  *       |  +-----+
                     +--+ R3+---------+ R4+----------+
                     *  +---+         +---+  *
                     *                       *
                     *************************

               Figure 2: RLD depolyment by a single ISP











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   As shown in Figure 2, with the RLD TLV attached to each Route
   Monitoring Message, the RLD server (also working as the BMP server)
   combines the BMP Adj_RIB_In message collected from R1 and the BMP
   Adj_RIB_Out message collected from R4 to decide if there's a route
   leak.  For example, if the RLD TLV in R1's Adj_RIB_In message
   indicates a value of "0", and the RLD TLV in R4's Adj_RIB_Out message
   indicates a value of "1", then the RLD server knows there exists a
   route leak.

4.3.  Coordination with iOTC and RLP

   RLD can be used as a complementary method to the existing methods
   against route leaks.  More specifically, RLD can coordination with
   both iOTC and RLP.

   *  With the settlement of the iOTC draft, the iOTC attribute is
      naturally included in the BGP Update and can be collected to the
      BMP server without BMP extension.  With the RLD TLV collected also
      by BMP (more specifically, the iBGP Adj-RIB-In of the ingress
      node), the BMP server can do validate the consistency of the iOTC
      attribute with the RLD.  If contradiction detected, the BMP server
      may further check the bussiness contract for the actual business
      relationship.

   *  For special prefixes that does not obey the peer/AS level business
      relationship negotiated through BGP Open Message, the BMP server
      can use the RLD TLV to detect such routes since the RLD TLV is set
      at prefix level.

   *  For devices that do not support RLP, using RLD to collect the BGP
      routes, which conveys the RLD information from upstream ASes,
      allows the BMP server to detect and mitigate the route leaks that
      happen in the upstream AS.  In other words, the detection and
      mitigation process can be also done in the BMP server, should the
      BMP server collects the BGP Update messages at the ingress or
      egress nodes.

5.  Acknowledgements


6.  Contributors

   Haibo Wang

   Huawei

   Email: rainsword.wang@huawei.com




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7.  IANA Considerations

   This document defines the following new BMP Route Monitoring message
   TLV type (Section 4.1):

   *  Type = TBD1, the RLD TLV represents the prefix-level business
      relationship between the transmitter AS and the receiver AS.  The
      local AS is a transmitter or a receiver, depending on if the route
      is an incoming route from a neighbor AS or an outgoing route to a
      neighbor AS.

8.  Security Considerations

   It is not believed that this document adds any additional security
   considerations.

9.  References

9.1.  Normative References

   [I-D.ietf-grow-route-leak-detection-mitigation]
              Sriram, K. and A. Azimov, "Methods for Detection and
              Mitigation of BGP Route Leaks", Work in Progress,
              Internet-Draft, draft-ietf-grow-route-leak-detection-
              mitigation-10, 8 January 2024,
              <https://datatracker.ietf.org/doc/html/draft-ietf-grow-
              route-leak-detection-mitigation-10>.

   [I-D.ietf-idr-bgp-open-policy]
              Azimov, A., Bogomazov, E., Bush, R., Patel, K., and K.
              Sriram, "Route Leak Prevention and Detection Using Roles
              in UPDATE and OPEN Messages", Work in Progress, Internet-
              Draft, draft-ietf-idr-bgp-open-policy-24, 1 April 2022,
              <https://datatracker.ietf.org/doc/html/draft-ietf-idr-bgp-
              open-policy-24>.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119,
              DOI 10.17487/RFC2119, March 1997,
              <https://www.rfc-editor.org/info/rfc2119>.

   [RFC4271]  Rekhter, Y., Ed., Li, T., Ed., and S. Hares, Ed., "A
              Border Gateway Protocol 4 (BGP-4)", RFC 4271,
              DOI 10.17487/RFC4271, January 2006,
              <https://www.rfc-editor.org/info/rfc4271>.






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   [RFC7854]  Scudder, J., Ed., Fernando, R., and S. Stuart, "BGP
              Monitoring Protocol (BMP)", RFC 7854,
              DOI 10.17487/RFC7854, June 2016,
              <https://www.rfc-editor.org/info/rfc7854>.

   [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, <https://www.rfc-editor.org/info/rfc7908>.

   [RFC8671]  Evens, T., Bayraktar, S., Lucente, P., Mi, P., and S.
              Zhuang, "Support for Adj-RIB-Out in the BGP Monitoring
              Protocol (BMP)", RFC 8671, DOI 10.17487/RFC8671, November
              2019, <https://www.rfc-editor.org/info/rfc8671>.

9.2.  Informative References

   [Luckie]   claffy, M. L. M. L. A. D. V. G. K., "AS Relationships,
              Customer Cones, and Validation", 23 October 2013.

   [Siddiqui] Ramirez, M. S. S. D. M. M. Y. R. S. X. M. W., "Route Leak
              Detection Using Real-Time Analytics on local BGP
              Information", 2014.

Authors' Addresses

   Yunan Gu
   Huawei
   Huawei Bld., No.156 Beiqing Rd.
   Beijing
   100095
   China
   Email: guyunan@huawei.com


   Huanan Chen
   China Telecom Co., Ltd.
   109 Zhongshan W Ave
   Guangzhou
   510630
   China
   Email: chenhn8.gd@chinatelecom.cn









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   Di Ma
   ZDNS
   4 South 4th St. Zhongguancun
   Beijing
   Haidian,
   China
   Email: madi@zdns.cn


   Nan Geng
   Huawei
   Huawei Bld., No.156 Beiqing Rd.
   Beijing
   100095
   China
   Email: gengnan@huawei.com


   Shunwan Zhuang
   Huawei
   Huawei Bld., No.156 Beiqing Rd.
   Beijing
   100095
   China
   Email: zhuangshunwan@huawei.com


























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