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Versions: 00                                                            
Internet Engineering Task Force                      R. Jaufeerally, Ed.
Internet-Draft                                                       TBD
Intended status: Standards Track                           30 March 2021
Expires: 1 October 2021


      An in-band BGP mechanism for looking-glass address discovery
                    draft-jaufeerally-bgp-lg-cap-00

Abstract

   This document specifies a mechanism by which eBGP speakers can
   propagate a BGP looking glass API endpoint address, in-band within a
   BGP session.  The looking glass API is defined by RFC 8522

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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   This Internet-Draft will expire on 1 October 2021.

Copyright Notice

   Copyright (c) 2021 IETF Trust and the persons identified as the
   document authors.  All rights reserved.

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   provided without warranty as described in the Simplified BSD License.






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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
     1.1.  Requirements Language . . . . . . . . . . . . . . . . . .   2
   2.  Capability wire format  . . . . . . . . . . . . . . . . . . .   2
   3.  Usage examples  . . . . . . . . . . . . . . . . . . . . . . .   3
   4.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .   4
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .   4
   6.  Normative References  . . . . . . . . . . . . . . . . . . . .   4
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .   5

1.  Introduction

   Autonomous systems that peer with one another using the Border
   Gateway Protocol (RFC 4271 [RFC4271]) do not have an automated way to
   tell if the prefixes announced over a particular peering link are
   acceped by the peer.  One way in which an AS operator can verify
   acceptance of routes by a peer is using a looking glass which may be
   provided by the peer, however this introduces manual toil in the
   operation and turnup of peering links.

   This document proposes a mechanism building on the looking glass API
   defined in RFC 8522 [RFC8522] to enable the automatic discovery of
   the looking glass endpoint, and therefore enable the automated
   probing of announcement acceptance by a peer, for instance.

   The mechanism by which this is achieved is to intoduce a new BGP
   capability which is sent in an OPEN message at session establishment
   time.

1.1.  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].

2.  Capability wire format

   The capability is composed of two parts, the header and payload.

   The following shows the wire format of the capability payload header:

    0 1 2 3 4 5 6 7
   +-+-+-+-+-+-+-+-+
   |Version| Type  | ... varies based on type ...
   +-+-+-+-+-+-+-+-+

                                  Figure 1



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   This document defines version 1 of the capability, and as such the
   Version field MUST be set to 1.  Implementations MUST discard the
   capability if the version number is not recognized.

   Type can be set to one of two values:

                      +-------+--------------------+
                      | Value | Description        |
                      +=======+====================+
                      | 1     | On router endpoint |
                      +-------+--------------------+
                      | 2     | URL endpoint       |
                      +-------+--------------------+

                      Table 1: Type field in header

   When the type field is set to 1, the capability MUST contain the
   following two bytes after the header which represent the TCP port:

    0             7 8             15
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
   |            tcp_port           |
   +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

                                  Figure 2

   The tcp_port field is a 16-bit unsigned integer encoded in network
   byte order, which represents the TCP port on the peer BGP speaker
   (i.e. the BGP peer IP address) that the looking glass is available
   at.

   When the type field is set to two the rest of the capability contains
   an ASCII encoded string representing a URL where the looking glass
   endpoint can be found.  This URL MUST conform to RFC 3986 [RFC3986]

   In both cases, the looking glass endpoint advertised MUST conform to
   RFC 8522 [RFC8522].

3.  Usage examples

   Between peers who have a direct BGP peering connection this capabilty
   will allow for direct probing of the routing state of the peer AS to
   determine if advertised routes were accepted.








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   On an internet exchange, the route server can advertise this
   capability to expose the route server looking glass, which whilest
   not providing information on if peers have accepted the routes,
   provides a way to check that routes are being propagated to peers on
   the route server.

4.  IANA Considerations

   This memo requests a BGP capability code from IANA in the 64 through
   127 range using the first come first served policy defined by RFC
   5492 [RFC5492].

5.  Security Considerations

   This draft proposes a mechanism for providing more easily automatable
   access to a looking glass interface operated by a network.  The scope
   of the dissemination of these looking glass adresses is to direct
   peers which are presumed to have an interest in querying the network
   reachability information, for example as part of debugging.

   Many network operators already provide looking glass services to the
   general public, however these are usually not standardized in their
   interfaces, and moreover, are not discoverable in an automated way
   which makes scalability difficult, and thus this draft
   programatically propagates that information.

   Operators MUST treat connections to the looking glass as untrusted.
   Operators SHOULD perform apppropriate rate-limiting and MAY deny
   abusive clients as per their own policy

   Operators may operate the looking glass with an IP access control
   list in cases where access is intended only for the peer, however
   this is discouraged as running a public facing looking glass brings
   the benefit that anyone can use it to debug network issues.

6.  Normative References

   [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>.

   [RFC8522]  Stubbig, M., "Looking Glass Command Set", RFC 8522,
              DOI 10.17487/RFC8522, February 2019,
              <https://www.rfc-editor.org/info/rfc8522>.






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   [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>.

   [RFC3986]  Berners-Lee, T., Fielding, R., and L. Masinter, "Uniform
              Resource Identifier (URI): Generic Syntax", STD 66,
              RFC 3986, DOI 10.17487/RFC3986, January 2005,
              <https://www.rfc-editor.org/info/rfc3986>.

   [RFC5492]  Scudder, J. and R. Chandra, "Capabilities Advertisement
              with BGP-4", RFC 5492, DOI 10.17487/RFC5492, February
              2009, <https://www.rfc-editor.org/info/rfc5492>.

Author's Address

   Rayhaan Jaufeerally (editor)
   TBD
   CH- Zurich
   Swiss Confederation

   Email: rayhaan+ietf@rayhaan.ch





























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