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Versions: 00 01 02

idr                                                            W. Kumari
Internet-Draft                                                    Google
Intended status: Informational                                  K. Patel
Expires: April 21, 2013                                    Cisco Systems
                                                              J. Scudder
                                                        Juniper Networks
                                                        October 18, 2012


                       Automagic peering at IXPs.
                     draft-wkumari-idr-socialite-02

Abstract

   This document describes a method for automatically establishing BGP
   peering sessions at an Internet exchange point.  Creation of these
   peering sessions is facilitated by a host.

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 http://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 April 21, 2013.

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
   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 and restrictions with respect
   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



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   described in the Simplified BSD License.


Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Requirements notation  . . . . . . . . . . . . . . . . . .  3
   2.  Terminology  . . . . . . . . . . . . . . . . . . . . . . . . .  4
   3.  Overview . . . . . . . . . . . . . . . . . . . . . . . . . . .  4
   4.  Protocol Extensions  . . . . . . . . . . . . . . . . . . . . .  4
     4.1.  Debut Capability . . . . . . . . . . . . . . . . . . . . .  4
   5.  Packet Formats . . . . . . . . . . . . . . . . . . . . . . . .  4
     5.1.  Message Header . . . . . . . . . . . . . . . . . . . . . .  5
     5.2.  INTRODUCTION Record  . . . . . . . . . . . . . . . . . . .  6
     5.3.  WITHDRAW Record  . . . . . . . . . . . . . . . . . . . . .  7
   6.  Protocol operation . . . . . . . . . . . . . . . . . . . . . .  7
   7.  Operational overview / implications  . . . . . . . . . . . . .  8
     7.1.  Additional eBGP sessions.  . . . . . . . . . . . . . . . .  8
     7.2.  Simplified debugging.  . . . . . . . . . . . . . . . . . .  8
     7.3.  BGP PATH / SIDR implications . . . . . . . . . . . . . . .  8
   8.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
     8.1.  Debut TYPE registry  . . . . . . . . . . . . . . . . . . .  9
   9.  Security considerations  . . . . . . . . . . . . . . . . . . .  9
     9.1.  Privacy  . . . . . . . . . . . . . . . . . . . . . . . . . 10
   10. Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 10
   11. Author Notes . . . . . . . . . . . . . . . . . . . . . . . . . 10
     11.1. Changelog. . . . . . . . . . . . . . . . . . . . . . . . . 10
     11.2. Changes from -00 to -01  . . . . . . . . . . . . . . . . . 10
     11.3. Changes from -01 to -02  . . . . . . . . . . . . . . . . . 11
   12. References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     12.1. Normative References . . . . . . . . . . . . . . . . . . . 11
     12.2. Informative References . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 11


















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1.  Introduction

   A large amount of Internet traffic is exchanged at Internet Exchange
   Points (IXP).  These are networks that are specifically built and
   operated as locations for networks to peer and exchange traffic.

   Public peering refers to peering across the (IXP provided) switch
   fabric.  In order to avoid having each participant at the IXP having
   to contact all of the other participants to enter into peering
   relationships, the IXP often provides a Route Server (RS).  The Route
   Server is a BGP speaker that participants peer with and announce
   routes to.  The Route Server takes these announcements and serves
   them to all of the other participants who peer with it (so far this
   is just like any other BGP router!).  The Route Server differs from a
   standard eBGP speaker in that it neither updates the Next Hop, nor
   prepends its own AS to the AS Path attribute.  By not changing the
   Next Hop attribute, traffic between participants flows directly
   between those participants (and does not pass through the Route
   Server), as the traffic doesn't flow though it, it is appropriate
   that it doesn't appear in the AS Path - this is known as a
   transparent Route Server (by not showing up in the AS Path, the fact
   that the peering between the participants occurs over a public
   peering session is hidden, and participants are not penalized by
   having longer AS Paths).

   This document describes an alternate solution for peering at an IXP.
   Instead of having a server that re-announces the routes from each
   participant to all of the others, we introduce a "socialite", a
   device that is responsible to making introductions between all of the
   participants and facilitating connections between them.  This
   socialite can be thought of like a host at a dinner party.  The
   guests arrive and the socialite introduces them to each other, and
   then steps out of the way to allow them to communicate (and peer!) on
   their own.

   This solution is aimed at operators who are currently peering with
   route-servers (and operators of those route-servers), and it is not
   expected to be a good alternative to "private peerings".

1.1.  Requirements notation

   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 [RFC2119].







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2.  Terminology

   Internet Exchange Point  A network for exchanging BGP routing
      information and traffic.
   Route Server  A BGP speaker at an IXP that "reflects" routes from one
      participant to all the other participants.  See
      [I-D.jasinska-ix-bgp-route-server]
   Socialite  A device running the Introduction protocol, responsible
      for making introductions between Guests.
   Guests  Participants of the IXP that speak the Debut protocol with
      the Socialite, and are introduced by the Socialite to other
      Guests.
   Debut  The protocol spoken between the Socialite and the Guests.


3.  Overview

   The Guests at the IXP form a BGP peering relationship with the
   Socialite, announcing support for the Debut protocol.  The Socialite
   sends the Guests a set of Debut updates, containing informations
   about the other participants.  The Guests use this information to
   form direct BGP peerings between themselves.  Policy can be
   configured on the Socialite to only make introductions between
   subsets of participants if so desired.


4.  Protocol Extensions

   The BGP protocol extensions introduced in this document include the
   definition of a new BGP capability, named "'Debut Capability", and
   the specification of the message subtypes for the Debut messages.

4.1.  Debut Capability

   The "Debut Capability" is a new BGP capability [RFC5492].  The
   Capability Code for this capability is specified in the IANA
   Considerations section of this document.  The Capability Length field
   of this capability is zero.  By advertising this capability to a
   peer, a BGP speaker conveys to the peer that the speaker supports the
   message subtypes for the Debut protocol and the related procedures
   described in this document.


5.  Packet Formats

   The Debut protocol is implemented using TLV structures, and fields
   are in network byte order.  These TLV records are carried as payload
   in a standard BGP Message packet (RFC 4271, Section 4.1. Message



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   Header Format ) [RFC4271]

5.1.  Message Header

   The Debut protocol is implemented using the standard Type-Length-
   Value paradigm.

   All Debut messages are carried as payload in a standard BGP Message
   of Type [TBD_BGP] and are preceded by a standard header that specific
   the type and length of the message.

       0 1 2 3 4 5 6 7              15                              31
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      | VER   |  RES  |          TYPE             |       LENGTH      |
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
      |                   VALUE (Variable Length)                     |
      ~                                                               ~
      ~                                                               ~
      +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+


   o  VER (4 bits): The VER (version) field specifies the version of the
      Debut protocol.  For the initial (this) version of the protocol it
      will be set to 0.
   o  RES (4 bits): The RES (reserved) field is reserved in the initial
      (this) version of the protocol.  It SHOULD be initialized to 0 on
      transmit and should be ignored on reception.
   o  TYPE (2 octets): The TYPE field species the TYPE of the TLV
      record, and allows an implementation to determine what type of
      information is carried in the record.  If the highest bit of the
      TYPE field is set (the TYPE value is >= 32786), understanding /
      implementation of the TYPE is optional - if an implementation does
      not implement this type it may ignore this message (this
      capability is included to allow for possible future logging,
      diagnostics, etc).  If the highest bit is not set, and the
      implementation receives a TYPE that it does not implement, it
      should send a BGP NOTIFY and tear down the session.  The TYPE
      codes are defined in the
   o  LENGTH (2 octets): The number of octets in the VALUE field of the
      TLV record.  The total length of the TLV record in octets can be
      calculated by adding 4 (the number of octets in the TYPE and
      LENGTH fields) to the value of this field.  This allows
      implementations to skip over TLV records that it cannot handle.
   o  VALUE (Variable length): The actual data.  The meaning of this
      data is given by the TYPE filed, and the length by the LENGTH
      field.  Parsing of the data field is performed according to the
      value of the TYPE field.




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5.2.  INTRODUCTION Record

   INTRODUCTION (TYPE 0) TLV records are used to "make introductions"
   between the Guests speaking the Debut protocol.  They carry the
   information needed by Guests to contact the other Guests and
   establish a BGP peering session.

        0 1 2 3 4 5 6 7                15                24           32
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    0: |                          NEIGHBOR AS                          |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    4: |          AFI                  |   SAFI          |     LEN     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
       |                             ADDRESS                           |
       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
       /                                                               /
       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+
    x: |                              Auth                             |
       +---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+---+

   o  NEIGHBOR AS (4 octets): This specifies the Autonomous System of
      the Guest being introduced.  In "Four-octet AS Number" format as
      specified in RFC4893 [RFC4893]
   o  AFI (2 octets): Address Family Identifier [RFC4760] [RFC4760]
   o  SAFI (1 octet): Subsequent Address Family Identifier [RFC4760]
      [RFC4760]
   o  LEN (1 octet): The length of the address in the ADDRESS field (32
      for IPv4, 128 for IPv6).
   o  ADDRESS (Variable length) This contains the IP Address of the
      Guest being introduced.
   o  Auth (optional, variable length): The existence of this field is
      determined from LENGTH of the TLV.  If the LENGTH is greater than
      the length of NEIGHBOR AS, FAMILY and ADDRESS, there is Auth
      data).

   The AFI and SAFI are included in the INTRODUCTION message to allow
   the Socialite to introduce Guests with multiple address families.

   On reception of an INTRODUCTION message a Guest should store the
   information and then consult local policy (if any) to determine if it
   is willing to peer with the newly introduced Guest.  If so, it should
   proceed as though this were a manually configured peer.  This peering
   SHOULD be annotated to note that this is a Socialite created peering.
   It is recommended that the peering show up in the configuration, but
   not persist across reboots -- this is to allow operators to more
   easily see all neighbors while looking through the config.





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5.3.  WITHDRAW Record

   WITHDRAW (TYPE 1) TLV records are used to inform a Guest that another
   previously introduced Guest is no longer participating.  A Guest can
   use this information to abort in progress connection attempts,
   invalidate information from a cache, for informational logging or in
   any other way is sees fit, but it SHOULD NOT use this information to
   tear down peering sessions to other Guests in ESTABLISHED state.
   Debut is intended to make initial introductions between participants
   and does not provide any mechanisms to invalidate / abort sessions
   once the introductions have been made.

   If a Socialite attempts to unintroduce an unknown Guest, this
   information should be logged and then ignored.

        0 1 2 3 4 5 6 7                15                24           32
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    0: |          AFI                  |   SAFI          |     LEN     |
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
    4: |                            ADDRESS                            \
       +-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+

   o  AFI (2 octets): Address Family Identifier [RFC4760] [RFC4760]
   o  SAFI (1 octet): Subsequent Address Family Identifier [RFC4760]
      [RFC4760]
   o  LEN (1 octet): The length of the address in the ADDRESS field (32
      for IPv4, 128 for IPv6).
   o  ADDRESS (Variable length): This contains the IP address of the
      Guest that is no longer participating.

   The AFI and SAFI are included so that the Socialite can inform Guests
   that only one of the AFI / SAFIs is being removed.


6.  Protocol operation

   Debut BGP sessions behave just like any other BGP sessions, just the
   information carried is different - Guests should use the standard BGP
   peering process to contact Socialites (or Socialites, Guests).  Once
   the peering is ESTABLISHED, Guests will begin receiving INTRODUCTION
   messages in UPDATES, and will store them in something resembling Adj-
   RIB-IN.  Standard BGP logic applied for things like error handling,
   invalidation of previously received information, etc.

   As Debut is only intended to make initial introductions between
   Guests (and not to manage sessions between those Guests), if the BGP
   session between Guest and Socialite goes down, established BGP
   peerings between Guests will continue to remain active.



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7.  Operational overview / implications

   There are many reasons why participants peer with route-servers at
   IXPs (see [I-D.jasinska-ix-bgp-route-server]) including
   o  reducing the administrative burden of arranging and configuring
      BGP sessions with all the other participants,
   o  not wanting (or being able) to carry views from all the
      participants,
   o  relying on the IXP operator to implement routing policy decisions
      (see [I-D.jasinska-ix-bgp-route-server], section 2.3)

   This solution only attempts to address the first reason for using a
   route-server, and the implications of deploying this are described
   below.

7.1.  Additional eBGP sessions.

   Debut is used to make introductions between all (or a subset of)
   participants at an IXP, and then the participants peer over "regular"
   BGP peerings.  This means that each participating router will build a
   separate BGP peering session with every other participating router.
   As participants at IXPs (usually) only advertise a small subset of
   the full Internet routing table (such as internal or customer routes)
   and there is (usually) not a huge overlap of this routing
   information, the additional memory requirements are expected to not
   be too onerous (especially with the capacity of modern routers).  As
   with all operational matters though, "Your network, your rules"
   applies -- it is up to each operator to determine the applicability /
   utility of the solution and how it fits (or doesn't) into their
   network (see what I did there?  If this ends poorly, it's your own
   fault!)

7.2.  Simplified debugging.

   As "normal" eBGP peering sessions are setup between the participants
   (and there is no third party performing route-selection, etc),
   operators have more visibility into the system and can more easily
   leverage their existing troubleshooting / debugging skills to debug
   issues.  Debut also more closely aligns the data and control plane,
   etc.

7.3.  BGP PATH / SIDR implications

   Part of the justification for this work is to simplify the design and
   implementation of path security in SIDR.  As a Route-Server passes
   routing information between peers, but does not show up in the BGP
   AS-PATH it is indistinguishable from a BGP path shortening attack.
   By using Debut, eBGP speakers peer directly with each other and this



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   problem is avoided.


8.  IANA Considerations

   IANA is requested to assign an AFI and SAFI for the Debut protocol.
   The text TBD1 should be replaced with the allocated AFI and the text
   TBD2 should be replaced with the allocated SAFI (and then this
   sentence should be removed).

   The IANA is requested to assign a value from the "BGP Message Types"
   registry and replace the text [TBD_BGP] with this value.  The
   definition should be "Debut protocol".

8.1.  Debut TYPE registry

   This document creates a new registry, "Debut Message Types".

   The registry policy is ""Specification Required".

   The initial entries in the registry are:

   Value        Short description    Reference
   -------------------------------------------------
   0            INTRODUCTION         [This]
   1            WITHDRAW             [This]
   2-3200       Unassigned
   3200-32767   Private Use
   32768-65480  Unassigned
   65481-65535  Private Use

   Applications to the registry can request specific values that have
   yet to be assigned.


9.  Security considerations

   This protocol is designed to facilitate direct BGP peerings between
   participants at an IXP, which eliminates the need for transparent
   route servers (which do not show up in the AS_PATH).  This will
   facilitate the deployment of SIDR.

   As participants peer with each other directly (and not through a
   third party) there is less opportunity for malicious tampering with
   the control plane (for example, by the IXP).

   Debut currently does not provide a means to securely distribute
   Authentication information (there is a field, but it's not really



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   defined).  Depending on if needed this may be addressed.

   An attacker who manages to subvert the Socialite (or inject UPDATES
   that into the Socialite to Guest communication) will be able to make
   Guests peer with a device under his control -- the impact of this
   seems to be no worse than in the routeserver model.

   Currently routeserver operators perform some base level checking /
   sanitization of routing information (such as enforcing max-paths) -
   in the socialte model each operator is expected to perform thier own
   checks.

9.1.  Privacy

   By having participants peer directly (as opposed to having their
   routing information pass through a route-server) the routing
   information is hidden from the IXP / route-server operator.  Please
   note that this doesn't protect the data-plane, and the routing
   information could still be sniffed off the wire.

   The biggest concern with regards to privacy on a route server is
   towards propagating your policy to a third party, rather than
   propagating your routing information.


10.  Acknowledgements

   The authors wish to thank Elisa Jasinska, Masataka MAWATARI, Robert
   Raszuk, Martin Hannigan, Simon Leinen.


11.  Author Notes

   [ RFC Editor -- Please remove this section before publication! ]

   1.  Choose a better name than "Debut"

11.1.  Changelog.

   o  Changed the name of the protocol from 'elo-'elo to Debut - this is
      still not great, but "Introduction" is worse.
   o  Added Operational section, incorporated notes from John Scudder,
      Keyur.

11.2.  Changes from -00 to -01






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   o  Incorporated some comments from Elisa Jasinska
   o  Mainly version bump tp prevent expire!

11.3.  Changes from -01 to -02

   o  Incorporated some long lingering nits / suggestions.
   o  9 or 10 folk have expressed interest and asked us to revive this.
      I (Warren) have done a really poor job of taking notes and
      incorporating them.  Appologies, if you mentioned issues to me in
      person I have probably forgotten to incorporate them, *please*
      send them in email and I'll get to them.
   o  Clarified the audience slightly, improved some security bits.


12.  References

12.1.  Normative References

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

   [RFC4271]  Rekhter, Y., Li, T., and S. Hares, "A Border Gateway
              Protocol 4 (BGP-4)", RFC 4271, January 2006.

   [RFC4760]  Bates, T., Chandra, R., Katz, D., and Y. Rekhter,
              "Multiprotocol Extensions for BGP-4", RFC 4760,
              January 2007.

   [RFC4893]  Vohra, Q. and E. Chen, "BGP Support for Four-octet AS
              Number Space", RFC 4893, May 2007.

12.2.  Informative References

   [I-D.jasinska-ix-bgp-route-server]
              Jasinska, E., Hilliard, N., Raszuk, R., and N. Bakker,
              "Internet Exchange Route Server",
              draft-jasinska-ix-bgp-route-server-03 (work in progress),
              October 2011.













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Authors' Addresses

   Warren Kumari
   Google
   1600 Amphitheatre Parkway
   Mountain View, CA  94043
   US

   Email: warren@kumari.net


   Keyur Patel
   Cisco Systems


   Phone:
   Fax:
   Email: keyupate@cisco.com
   URI:


   John Scudder
   Juniper Networks
   1194 N. Mathilda Ave
   Sunnyvale,   CA
   USA

   Phone:
   Fax:
   Email: jgs@juniper.net
   URI:




















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