Enhanced AS-Loop Detection for BGP
draft-chen-grow-enhanced-as-loop-detection-00

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Network Working Group                                            H. Chen
Internet-Draft                                             China Telecom
Intended status: Best Current Practice                             Y. Gu
Expires: September 13, 2019                                    S. Zhuang
                                                                 H. Wang
                                                                  Huawei
                                                          March 12, 2019

                   Enhanced AS-Loop Detection for BGP
             draft-chen-grow-enhanced-as-loop-detection-00

Abstract

   This document proposes to enhance AS-Loop Detection for BGP Inbound/
   Outbound Route Processing.

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
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   Drafts is at https://datatracker.ietf.org/drafts/current/.

   Internet-Drafts are draft documents valid for a maximum of six months
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   This Internet-Draft will expire on September 13, 2019.

Copyright Notice

   Copyright (c) 2019 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

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   publication of this document.  Please review these documents
   carefully, as they describe your rights and restrictions with respect
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   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  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Terminology . . . . . . . . . . . . . . . . . . . . . . . . .   4
   3.  Enhanced AS-Loop Detection for BGP Inbound Route Processing .   5
   4.  Enhanced AS-Loop Detection for BGP Outbound Route Processing    7
   5.  Benefits  . . . . . . . . . . . . . . . . . . . . . . . . . .   7
   6.  Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .   7
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   8
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .   8
   9.  Normative References  . . . . . . . . . . . . . . . . . . . .   8
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .   8

1.  Introduction

   The Border Gateway Protocol (BGP) [RFC4271], as an inter-Autonomous
   (AS) routing protocol, is used to exchange network reachability
   information between BGP systems.  BGP is widely used by Internet
   Service Providers (ISPs) and large organizations.

   BGP is used to exchange reachable inter-AS routes, establish inter-AS
   paths, avoid routing loops, and apply routing policies between ASs.
   BGP loop detection mechanism is defined in section 9.1.2. of RFC4271:

      ...

      If the AS_PATH attribute of a BGP route contains an AS loop, the
      BGP route should be excluded from the Phase 2 decision function.
      AS loop detection is done by scanning the full AS path (as
      specified in the AS_PATH attribute), and checking that the
      autonomous system number of the local system does not appear in
      the AS path.  Operations of a BGP speaker that is configured to
      accept routes with its own autonomous system number in the AS path
      are outside the scope of this document.

      ...

   In ordinary BGP, every AS announces its route information with
   different prefixes.  However, its neighboring ASes cannot validate
   this route information, but rather directly propagate it across the
   Internet or simply discard AS-Loop routes directly.  Obviously, this

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   weak trust model allows forged route announcement propagations and
   rarely been found, which is a fundamental security weakness of BGP.
   Forged routes, which can be generated by configuration errors or
   malicious attacks, can cause large-scale network connectivity