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IDR                                                      G. Van de Velde
Internet-Draft                                                  K. Patel
Intended status: Standards Track                           Cisco Systems
Expires: December 31, 2012                                     R. Raszuk
                                                            NTT MCL Inc.
                                                                 R. Bush
                                               Internet Initiative Japan
                                                               July 2012


                          BGP Remote-Next-Hop
                draft-vandevelde-idr-remote-next-hop-01

Abstract

   The BGP Remote-Next-Hop is a new optional transitive attribute
   intended to facilitate automatic tunneling within an AS on a per
   address family basis.  The attribute carries one or more tunnel end-
   points for a NLRI.  Additionally tunnel encapsulation information is
   communicated to successfully setup these tunnels.

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
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   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 31, 2012.

Copyright Notice

   Copyright (c) 2012 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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   Provisions Relating to IETF Documents (http://trustee.ietf.org/
   license-info) in effect on the date of publication of this document.
   Please review these documents carefully, as they describe your rights
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   provided without warranty as described in the Simplified BSD License.

Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  2
   2.  Requirements Language  . . . . . . . . . . . . . . . . . . . .  2
   3.  Tunnel Encapsulation attribute versus BGP Remote-Next-Hop
       attribute  . . . . . . . . . . . . . . . . . . . . . . . . . .  3
   4.   BGP Remote-Next-Hop attribute TLV Format  . . . . . . . . . .  3
   5.  Use Case scenarios . . . . . . . . . . . . . . . . . . . . . .  4
     5.1.  Multi-homing for IPv6  . . . . . . . . . . . . . . . . . .  4
     5.2.  Dynamic Network Overlay Infrastructure . . . . . . . . . .  5
     5.3.  The Tunnel end-point is NOT the originating BGP speaker  .  5
     5.4.  Networks that do not support BGP Remote-Next-Hop attribute  5
     5.5.  Networks that do NOT support BGP Remote-Next-Hop attribute  5
   6.  BGP Remote-Next-Hop Community  . . . . . . . . . . . . . . . .  5
   7.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  5
   8.  Security Considerations  . . . . . . . . . . . . . . . . . . .  6
     8.1.  Protecting the validity of the BGP Remote-Next-Hop attribut 6
   9.  Privacy Considerations . . . . . . . . . . . . . . . . . . . .  6
   10. Change Log . . . . . . . . . . . . . . . . . . . . . . . . . .  6
   11. References . . . . . . . . . . . . . . . . . . . . . . . . . .  6
     11.1.  Normative References  . . . . . . . . . . . . . . . . . .  6
     11.2.  Informative References  . . . . . . . . . . . . . . . . .  7
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . .  7

1.  Introduction

   [RFC5512] defines an attribute attached to an NLRI to signal tunnel
   end-point addresses and encapsulation information between two BGP
   speakers.  It assumes that the exchanged tunnel endpoint is the NLRI.

   This note defines a Remote-Next-Hop BGP attribute for Intra-AS and
   Inter-AS usage which removes that assumption.

   The Address Family (AF) of the NLRI exchanged is decoupled from the
   address-family of the BGP Remote-Next-Hop address-family.  For each
   NLRI, multiple BGP Remote-Next-Hop attributes of various address-
   families could be inserted.

2.  Requirements Language

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   "SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" are to
   be interpreted as described in [RFC2119] only when they appear in all
   upper case.  They may also appear in lower or mixed case as English
   words, without any normative meaning.


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3.  Tunnel Encapsulation attribute versus BGP Remote-Next-Hop attribute

   The Tunnel Encapsulation attribute [RFC5512] is based on the
   principle that the tunnel end-point is the BGP speaker originating
   the update and is inserted as the NLRI in the exchange, with the
   consequence that it is impossible to set the endpoint it to an
   arbitrary IP address.

   There are use cases where it is desired that the tunnel end-point
   address should be a different address, or set of addresses, than the
   originating BGP speaker.  The BGP Remote-Next-Hop attribute provides
   the ability to have one or more different tunnel end-point addresses
   from either the IPv4 and/or the IPv6 address-families.

   The sub-TLVs from the Tunnel Encapsulation Attribute [RFC5512] are
   reused for the BGP Next-Hop-Attribute.

   Due to the intrinsic nature of both attributes, that the tunnel
   encapsulation end-point assumes that the tunnel end-point is both the
   NLRI exchanged and the originating router, while the BGP Remote-Next-
   Hop attribute is inserted for an exchanged NLRI by adding a set of
   tunnel end-points, these two attributes are mutually exclusive.

4.  BGP Remote-Next-Hop attribute TLV Format

   This attribute is an optional transitive attribute [RFC1771].

   The BGP Remote-Next-Hop attribute is is composed of a set of Type-
   Length-Value (TLV) encodings.  The type code of the attribute is
   (IANA to assign). Each TLV contains information corresponding to a
   particular tunnel technology and tunnel end-point Address.  The TLV
   is structured as follows:






















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      0                   1                   2                   3
      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
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |   Tunnel Type (2 Octets)    |              Length             |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | Addr len    |     Tunnel Address (IPv4 or IPv6)               |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                          AS Number                            |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

      |                   Tunnel Parameters                           |
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


      Tunnel Type (2 octets): identifies the type of tunneling technology
      being signaled.  This document defines the following types:

      - L2TPv3 over IP [RFC3931]: Tunnel Type = 1
      - GRE [RFC2784]: Tunnel Type = 2
      - IP in IP [RFC2003] [RFC4213]: Tunnel Type = 7

      Unknown types MUST be ignored and skipped upon receipt.

      Length (2 octets): the total number of octets of the value field.

      Tunnel Address Length - Addr len (1 octet): Length of Tunnel
      Address. Set to 4 bytes for an IPv4 address and 16 bytes for an
      IPv6 address.

      AS Number - The AS number originating the BGP Remote-Next-Hop
      attribute  and is either a 2-byte AS or 4-Byte AS number

      Value (variable): comprised of multiple sub-TLVs.  Each sub-TLV
      consists of three fields: a 1-octet type, 1-octet length, and zero
      or more octets of value.  The sub-TLV definitions and the sub-TLV
      data are described in depth in [RFC5512].

5.  Use Case scenarios

   This section provides a short overview of some use-cases for the BGP
   Remote-Next-Hop attribute.  Use of the BGP Remote-Next-Hop is not
   limited to the examples in this section.

5.1.  Multi-homing for IPv6

   When an end-user IPv6 network is multi-homed to the Internet, it may
   be assigned more than a single prefix originated by various upstream
   ASs.  Each AS prefers to only announce a supernet of all its assigned
   IPv6 prefixes, unlike IPv4 where the AS announced the end-users
   assigned prefix.  The goal of this BGP policy behaviour is to keep



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   the number of entries in the IPv6 global BGP table to a minimum, it
   also it also results in well known resiliency improvements.

   For example, if an end-user IPv6 is peering with 2 different Service
   providers AS1 and AS2.  In this case the IPv6 end-user will have at
   least one prefix assigned from each of these service providers.  The
   devices at the IPv6 end-user will each receive an address from these
   prefixes.  The devices will in most cases, when building IPv6
   sessions (TCP, etc...), do so with only a single IPv6 address.  The
   decision which IPv6 address the device will use is documented in
   [RFC3484].

   If one if the links between the end-user and one of the neighboring
   AS's breaks, a consequence will be that a set of sessions need to be
   reset, or that a section of the end-user network becomes unreachable.

   With usage of the BGP-remote-Next-Hop attribute the service provider
   can tunnel that packet towards an alternate BGP Remote-Next-Hop at
   the end-users alternate provider and restore the network connectivity
   even though the local link towards the end-user is broken.

5.2.  Dynamic Network Overlay Infrastructure

   With the BGP Remote-Next-Hop feature it is possible to build and
   dynamically create an overlay tunneled network with privacy, traffic
   isolation, and virtual private networks.

5.3.  The Tunnel end-point is NOT the originating BGP speaker

   Note that, in each network environment, the originating router is the
   preferred tunnel end-point server.  It may be that the network
   administrator has deployed an independent set of tunnel end-point
   servers across their network, which may or may not speak BGP. The BGP
   Remote-Next-Hop attribute provides the ability to signal this via
   BGP.

5.4.  Networks that do not support BGP Remote-Next-Hop attribute

   If a device does not support this attribute, and receives this
   attribute, then normal NLRI BGP forwarding is used as the attribute
   is optional and transitive.

5.5.  Networks that do NOT support BGP Remote-Next-Hop attribute

   If a BGP speaker does understand this attribute, and receives this
   attribute, then the BGP speaker MAY, by configuration, skip use or
   not use the information within this attribute.

6.  BGP Remote-Next-Hop Community

   place-holder for an BGP extension to signal valid prefixes allowed to
   be considered as tunnel end-points.  To be completed.

7.  IANA Considerations

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   This memo asks the IANA for a new BGP attribute assignment.

8.  Security Considerations

   This technology could be used as technology as man in the middle
   attack, however with existing RPKI validation for BGP that risk is
   reduced.

   The distribution of Tunnel end-point address information can result
   in potential DoS attacks if the information is sent by malicious
   organisations.  Therefore is it strongly recommended to install
   traffic filters, IDSs and IPSs at the perimeter of the tunneled
   network infrastructure.

8.1.  Protecting the validity of the BGP Remote-Next-Hop attribute

   It is possible to inject a rogue BGP Remote-Next-Hop attribute to an
   NLRI resulting in Monkey-In-The-Middle attack (MITM).  To avoid this
   type of MITM attack, it is strongly recommended to use a technology a
   mechanism to verify that for NLRI it is the expected BGP Remote-Next-
   Hop.  We anticipate that this can be done with an expansion of RPKI-
   Based origin validation, see [I-D.ietf-sidr-pfx-validate].

   This does not avoid the fact that rogue AS numbers may be inserted or
   injected into the AS-Path.  To achieve protection against that threat
   BGP Path Validation should be used, see [I-D.ietf-sidr-bgpsec-
   overview].

9.  Privacy Considerations

   This proposal may introduce privacy issues, however with BGP security
   mechanisms in place they should be prevented.

10.  Change Log

   Initial Version: 16 May 2012

   Hacked for -01: 17 July 2012

11.  References

11.1.  Normative References

   [RFC1771]  Rekhter, Y. and T. Li, "A Border Gateway Protocol 4
              (BGP-4)", RFC 1771, March 1995.

   [RFC2119]  Bradner, S., "Key words for use in RFCs to Indicate
              Requirement Levels", BCP 14, RFC 2119, March 1997.

   [RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D. and P. Traina,
              "Generic Routing Encapsulation (GRE)", RFC 2784, March
              2000.


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   [RFC3484]  Draves, R., "Default Address Selection for Internet
              Protocol version 6 (IPv6)", RFC 3484, February 2003.

   [RFC3931]  Lau, J., Townsley, M. and I. Goyret, "Layer Two Tunneling
              Protocol - Version 3 (L2TPv3)", RFC 3931, March 2005.

   [RFC4213]  Nordmark, E. and R. Gilligan, "Basic Transition Mechanisms
              for IPv6 Hosts and Routers", RFC 4213, October 2005.

   [RFC5512]  Mohapatra, P. and E. Rosen, "The BGP Encapsulation
              Subsequent Address Family Identifier (SAFI) and the BGP
              Tunnel Encapsulation Attribute", RFC 5512, April 2009.

11.2.  Informative References

   [I-D.ietf-sidr-bgpsec-overview]
              Lepinski, M. and S. Turner, "An Overview of BGPSEC",
              Internet-Draft draft-ietf-sidr-bgpsec-overview-02, May
              2012.

   [I-D.ietf-sidr-pfx-validate]
              Mohapatra, P., Scudder, J., Ward, D., Bush, R. and R.
              Austein, "BGP Prefix Origin Validation", Internet-Draft
              draft-ietf-sidr-pfx-validate-08, July 2012.

Authors' Addresses

   Gunter Van de Velde
   Cisco Systems
   De Kleetlaan 6a
   Diegem 1831
   Belgium

   Phone: +32 2704 5473
   Email: gvandeve@cisco.com


   Keyur Patel
   Cisco Systems
   170 W. Tasman Drive
   San Jose, CA 95124 95134
   USA

   Email: keyupate@cisco.com


   Robert Raszuk
   NTT MCL Inc.
   101 S Ellsworth Avenue Suite 350
   San Mateo, CA  94401
   US

   Email: robert@raszuk.net

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   Randy Bush
   Internet Initiative Japan
   5147 Crystal Springs
   Bainbridge Island, Washington 98110
   US

   Email: randy@psg.com













































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