Global Routing Operations                                    J. Snijders
Internet-Draft                                                J. Heasley
Intended status: Informational                                       NTT
Expires: August 20, September 13, 2017                                   M. Schmidt
                                                                 i3D.net
                                                       February 16,
                                                          March 12, 2017

                     Usage of BGP Large Communities
               draft-ietf-grow-large-communities-usage-02
               draft-ietf-grow-large-communities-usage-03

Abstract

   Examples and inspiration for operators for the use of BGP Large
   Communities.

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 [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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   This Internet-Draft will expire on August 20, September 13, 2017.

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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  The Generic Design Pattern Overview . . . . . . . . . . . . . . . . .   3 . . . .   2
     2.1.  Informational Communities . . . . . . . . . . . . . . . .   3   4
     2.2.  Action Communities  . . . . . . . . . . . . . . . . . . .   4
   3.  Examples of Informational Communities . . . . . . . . . . . .   4   5
     3.1.  Location  . . . . . . . . . . . . . . . . . . . . . . . .   4   5
       3.1.1.  An ISO 3166-1 numeric function  . . . . . . . . . . .   4   5
       3.1.2.  An UNSD region  A UN M.49 Region function . . . . . . . . . . . . . . .   5
     3.2.  Relation Function . . . . . . . . . . . . . . . . . . . . . . . .   5   6
     3.3.  Combining Informational Communities . . . . . . . . . . .   6
   4.  Examples of Action Communities  . . . . . . . . . . . . . . .   6   7
     4.1.  Selective NO_EXPORT . . . . . . . . . . . . . . . . . . .   6   7
       4.1.1.  Peer  ASN Based Selective NO_EXPORT . . . . . . . . .   6 . . .   7
       4.1.2.  Location Based Selective NO_EXPORT  . . . . . . . . .   7
     4.2.  Selective AS_PATH Prepending  . . . . . . . . . . . . . .   7   8
       4.2.1.  Peer  ASN Based Selective AS_PATH Prepending  . . . . .   7 . .   8
       4.2.2.  Location Based Selective AS_PATH Prepending . . . . .   8   9
     4.3.  Manipulation of the LOCAL_PREF attribute  . . . . . . . .   9
       4.3.1.  Global Manipulation of LOCAL_PREF . . . . . . . . . .  10
       4.3.2.  Location based manipulation Based Manipulation of LOCAL_PREF . . . . . .  10
       4.3.3.  Note of Caution for LOCAL_PREF Functions  . . .   8 . . .  11
   5.  Security Considerations . . . . . . . . . . . . . . . . . . .  10  11
   6.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10  11
   7.  Acknowledgements  Acknowledgments . . . . . . . . . . . . . . . . . . . . . .  10 .  11
   8.  References  . . . . . . . . . . . . . . . . . . . . . . . . .  10  12
     8.1.  Normative References  . . . . . . . . . . . . . . . . . .  10  12
     8.2.  URIs  . . . . . . . . . . . . . . . . . . . . . . . . . .  11  12
   Authors' Addresses  . . . . . . . . . . . . . . . . . . . . . . .  11  12

1.  Introduction

   BGP Large Communities [RFC8092] provide a mechanism to signal opaque
   information between Autonomous Systems.  This document presents a set
   of
   examples of how Large operators might utilise BGP Large Communities could be employed by an
   operator to
   achieve various goals.  This document draws from experience in Operational Communities of
   operational communities such as NANOG [1] and NLNOG [2].

   The opaque nature of BGP Large Communities allows for rapid
   deployment of new features or changes to the product.  Operators are
   encouraged to publicly publish and maintain documentation of the
   purpose of each Large BGP Community, both informational and action,
   that they support or are visible in looking glasses.

2.  The Generic Design Pattern Overview

   BGP Large Communities are composed of a 4-octet Global Administrator
   field followed by two 4-octet Local Data fields.  Large BGP
   Communities are compose three 4-octet fields.  The
   first is the Global Administrator (GA) field, whose value is the ASN
   Autonomous System Number (ASN) of AS the Autonomous System (AS) that has
   defined the meaning of the remaining two 4-octet fields, the Local known as
   "Local Data fields. Part 1" and "Local Data Part 2".  This document describes
   an approach defining these
   fields as "ASN:Function:Parameter"-approach to fill where the three fields.

   In deployments of both BGP Communities [RFC1997] "Local Data Part 1" field contains a function
   identifier and BGP Large
   Communities, two categories of Communities exist:

   o  Informational Communities

   o  Action Communities

   For each, ideas are provided regarding the contents of each of "Local Data Part 2" contains a parameter value.

   Using the
   three fields in BGP Large Communities.

   Throughout canonical notation the above can be summarized as
   "ASN:Function:Parameter".

                 +----------------------+---------------+
                 |       RFC 8092       | this document a topology |
                 +----------------------+---------------+
                 | Global Administrator |      ASN      |
                 |  Local Data Part 1   |    Function   |
                 |  Local Data Part 2   |   Parameter   |
                 +----------------------+---------------+

      A mapping table on the usage of fields in BGP Large Communities
                   between [RFC8092] and this document.

                          Table 1: Field mapping

   In contemporary deployments of both BGP Communities [RFC1997] and BGP
   Large Communities, the function of a community can be divided into
   two categories:

   o  Informational Communities

   o  Action Communities

   Throughout the document a topology of four Autonomous Systems is used
   to illustrate the usage of Communities in the following
   configuration:

           AS 65551
               |
               ^
               |
           AS 64497
             /  \
            ^    \
           /      ^
      AS 64498     \
          |        |
          `<->- AS 64499

   AS 64497 obtains transit services from (is a customer of) AS 65551, a
   32-bit ASN.  AS 64497 provides transit services to both AS 64498 and
   AS 64499.  AS 64498 and AS 64499 maintain a peering relationship in
   which they only exchange their customer routes.

   The opaque nature of BGP Large Communities allows for rapid
   deployment of new features or changes to products.  Operators are
   encouraged to publicly publish and maintain documentation of the
   purpose of each BGP Large Community, both informational and action,
   that they support or are visible in BGP RIBs.

2.1.  Informational Communities

   Informational Communites Communities are labels for attributes such as the
   origin of the route announcement, the nature of the relation with the an
   EBGP neighbor or for
   instance the intended propagation audience.  Informational
   Communities can also assist in providing valuable information for
   day-to-day network operations such as debugging. debugging or capacity planning.

   The Global Administrator field is set to the ASN which is marking labels the
   routes with the Informational Communities.  For example, AS 64497
   might add a community with the GA 64497 to a route learned accepted from an
   iBGP
   IBGP or eBGP peer that EBGP neighbor as a means of signaling that the route it was learned from or
   originated by a device imported in the Netherlands.
   a certain geographical region.

   In general general, the intended audience audiences of Informational Communities are
   downstream networks and the Global Administrator itself, but any
   Autonomous System could benefit from receiving these communities.

2.2.  Action Communities

   Action Communities are attached to routes added as a label to request non-default
   behaviour in this,
   treatment of a conferation or route within an external AS.  Action
   Communities could be used to change  The operator of that AS defines
   routing policy which, based upon the route's communities, adjusts route
   attributes such as its propagation characteristics, the LOCAL_PREFENCE LOCAL_PREF
   (local preference), the next-hop, or the number of AS_PATH prepends
   to add when exporting be added upon reception or importing a route. propagation.

   The Global Administrator field is set to the ASN which has defined
   the functionality of that BGP Large Community and is therefore the
   ASN that is expected to perform the action.  For instance, AS 64499
   might add label a route with a BGP Large Community with the containing GA 64497 to signal
   request that AS 64497 to perform an a pre-defined action upon that route.

   In general general, the intended audience of Action Communities is an upstream
   provider, are transit
   providers taking action on behalf of a customer or the Global
   Administrator itself, but realistically any AS could be take action if they chose and
   any AS willing to act upon it.

3.  Examples could add an action community with the GA of Informational Communities

3.1.  Location

   AS 64497 can inform its downstream a non-adjacent
   ASN.  However, note that an Action Community could also be
   informational.  Its presence is an indicator that the GA may have
   performed the action and that an AS in the AS_PATH requested it.

3.  Examples of Informational Communities

3.1.  Location

   An AS, AS 64497 in these examples, may inform other networks about
   the geographical
   entity region where AS 64497 learned imported a route by marking the route labeling
   it with BGP Large Communities following one or a combination of the following
   schemes. schemes
   or a combination thereof.

3.1.1.  An ISO 3166-1 numeric function

   AS 64497 could assign a value of 1 to the first Local Data Function field to designate
   the function content of the second Local Data Parameter field as an ISO-3166-1 [3] numeric
   country identifiers.

    +---------------------+-------------------------------------------+ identifier.

   +---------------------+---------------------------------------------+
   | BGP Large Community | Description                                 |
    +---------------------+-------------------------------------------+
   +---------------------+---------------------------------------------+
   |     64497:1:528     | Route learned in the Netherlands            |
   |     64497:1:392     | Route learned in Japan                      |
   |     64497:1:840     | Route learned in the United States of       |
   |                     | America                                     |
    +---------------------+-------------------------------------------+
   +---------------------+---------------------------------------------+

    Example documentation for AS 64497 using Informational Communities
   describing deployed by AS
    64497 to describe the origin of routes location where a route was imported using ISO
                        3166-1 numeric identifiers.

                     Table 1: 2: Information: ISO 3166-1

3.1.2.  An UNSD region  A UN M.49 Region function

   AS 64497 could assign a value of 2 to the first Local Data Function field to designate
   the function content of the parameter in the second Local Data Parameter field as an identifier for the M.49 numeric code published
   by the United Nations Statistics Division (UNSD) [4] for macro
   geographical (continental) regions, geographical sub-regions, or
   selected economic and other
   groupings following a set of published identifiers by the United
   Nations Statistics Division [3]. groupings.

          +---------------------+-------------------------------+
          | BGP Large Community | Description                   |
          +---------------------+-------------------------------+
          |      64497:2:2      | Route learned in Africa       |
          |      64497:2:9      | Route learned in Oceania      |
          |     64497:2:145     | Route learned in Western Asia |
          |     64497:2:150     | Route learned in Europe       |
          +---------------------+-------------------------------+

    Example documentation for AS 64497 using Informational Communities
   describing deployed by AS
   64497 to describe the origin of routes location where a route was imported using M.49
    numeric identifiers provided codes published by the UN United Nations Statistics Division.

                    Table 2: 3: Information: UNSD Regions

3.2.  Relation Function

   An AS, AS 64497 in this example, could assign a value of 3 to the first Local Data
   Function field to designate that the second Local Data content of the Parameter field contains an identifier
   showing as a
   number indicating whether the route originated inside its own network
   or was learned externally, and if learned externally, it might
   simultaneously characterize the nature of the relation with the that
   specific EBGP neighbor from whom the route was
   received.

     +---------------------+-----------------------------------------+ neighbor.

      +---------------------+---------------------------------------+
      | BGP Large Community | Description                           |
     +---------------------+-----------------------------------------+
      +---------------------+---------------------------------------+
      |      64497:3:1      | Route originated internally           |
      |      64497:3:2      | Route learned from a customer         |
      |      64497:3:2      64497:3:3      | Route learned from a peering partner  |
      |      64497:3:3      64497:3:4      | Route learned from an upstream a transit provider |
     +---------------------+-----------------------------------------+
      +---------------------+---------------------------------------+

    Example documentation for AS 64497 using Informational Communities
       describing deployed by AS
    64497 to describe the relation with to the ASN from which the route was
                                 received.
                                 learned.

                      Table 3: 4: Information: Relation

3.3.  Combining Informational Communities

   Multiple Informational Communities can

   A route may be tagged on a route, for
   example: labeled with multiple Informational Communities.  For
   example, a route learned in the Netherlands from a customer can
   contain both 64497:1:528 and might be
   labeled with communities 64497:1:528, 64497:2:150 and 64497:3:1. 64497:3:2 at
   the same time.

4.  Examples of Action Communities

4.1.  Selective NO_EXPORT

   As part of the an agreement, often a commercial agreement transit agreement,
   between AS 64497 and AS 64498, AS 64497 might offer AS 64498 certain expose BGP Traffic Engineering features
   such as selectively not export routes traffic
   engineering functions to AS 64498.  One such BGP traffic engineering
   function could be selective NO_EXPORT, which is the selective
   filtering of a route learned from 64498 one AS, AS 64498, to certain EBGP
   neighbors of the GA, AS 64497.

4.1.1.  Peer  ASN Based Selective NO_EXPORT

   AS 64497 might could assign function identifier a value of 4 to allow preventing
   propagation of routes the Function field to designate
   the ASN listed in content of the second Local Data
   field. Parameter field as a neighboring ASN to which a
   route should not be propagated.

         +---------------------+---------------------------------+
         | BGP Large Community | Description                     |
         +---------------------+---------------------------------+
         |     64497:4:2914    64497:4:64498    | Do not export route to AS 2914 64498 |
         |     64497:4:7018    64497:4:64499    | Do not export route to AS 7018 64499 |
         |    64497:4:65551    | Do not export route to AS 65551 |
         +---------------------+---------------------------------+

   Example documentation for AS 64497 offering Action Communities deployed by AS 64497 to
    limit
   expose a BGP traffic engineering function which selectively prevents
     the propagation of routes based on to the Peer neighboring ASN described specified in the
                               third
                             Parameter field.

                      Table 4: 5: Action: Peer ASN NO_EXPORT

4.1.2.  Location Based Selective NO_EXPORT

   AS 64497 might could assign function identifier a value of 5 to allow its customers the Function field to
   request selectively not exporting routes on EBGP sessions within a
   certain geographical area.  This example follows designate
   the content of the Parameter field as an ISO 3166-1 numeric encoding.

   +------------------+------------------------------------------------+ country
   identifier within which a labeled route is not propagated to EBGP
   neighbors.  However this might not prevent one of those EBGP
   neighbors from learning that route in another country and thereby
   making it available in the country specified by the BGP Large
   Community.

   +-----------------+-------------------------------------------------+
   |    BGP Large    | Description                                     |
   |    Community    |                                                 |
   +------------------+------------------------------------------------+
   +-----------------+-------------------------------------------------+
   |   64497:5:528   | Do not export to EBGP neighbors in the          |
   |                 | Netherlands                                     |
   |   64497:5:392   | Do not export to EBGP neighbors in Japan        |
   |   64497:5:840   | Do not export to EBGP neighbors in the United   |
   |                 | States of America                               |
   +------------------+------------------------------------------------+
   +-----------------+-------------------------------------------------+

   Example documentation for AS 64497 offering Action Communities deployed by AS 64497 to
     trigger NO_EXPORT on routes only when propagating
   expose a BGP traffic engineering function which selectively prevents
    the route propagation of routes to a
                       certain all EBGP neighbors in the geographical region.
                 region specified in the Parameter field.

                   Table 5: 6: Action: NO_EXPORT in Region

4.2.  Selective AS_PATH Prepending

   As part of the commercial an agreement between AS 64497 and AS 64498, AS 64497 might offer AS 64498 certain
   expose BGP Traffic Engineering features traffic engineering functions to AS 64498.  One such as selectively BGP
   traffic engineering function could be selective prepending of the
   AS_PATH with 64497's ASN AS 64497 to certain certain EBGP neighbors of AS 64497.

4.2.1.  Peer  ASN Based Selective AS_PATH Prepending

   AS 64497 might could assign function identifier a value of 6 to allow prepending the
   AS_PATH on propagation of routes Function field to designate
   the ASN listed in content of the second
   Local Data field.

    +---------------------+------------------------------------------+
    | BGP Large Community | Description                              |
    +---------------------+------------------------------------------+
    |     64497:6:2914    | Prepend 64497 once on export Parameter field as a neighboring ASN to which
   prepending of the AS_PATH with AS 2914  | 64497 is requested upon propagation
   of the route.  Additional AS_PATH Prepending functions might also be
   defined to support multiples of prepending, that is two, three or
   more prepends of AS 64497.

    +---------------------+------------------------------------------+
    | BGP Large Community | Description                              |
    +---------------------+------------------------------------------+
    |    64497:6:64498    | Prepend 64497 once on export to AS 64498 |     64497:6:7018
    |    64497:6:64499    | Prepend 64497 once on export to AS 7018 64499 |
    |    64497:6:65551    | Prepend 64497 once on export to AS 65551 |
    +---------------------+------------------------------------------+

   Example documentation for AS 64497 offering Action Communities deployed by AS 64497 to
   trigger prepending of
   expose a BGP traffic engineering function which selectively prepends
   the AS_PATH only with AS 64497 when propagating the route to
                            a certain Peer ASN. the specified
                              EBGP neighbor.

                      Table 6: 7: Action: Prepend to Peer ASN

4.2.2.  Location Based Selective AS_PATH Prepending

   AS 64497 might could assign function identifier a value of 7 to allow the Function field to designate
   the content of the Parameter field as an ISO 3166-1 numeric country
   identifier to which the prepending of the AS_PATH on with AS 64497 is
   requested upon propagation of routes the route to on any all EBGP neighbor's
   interconnection in the geographical entity listed in the second Local
   Data field.  This example follows the ISO 3166-1 numeric regions
   codes neighbors in the Local Data 2 field. that
   region.

   +------------------+------------------------------------------------+
   |    BGP Large     | Description                                    |
   |    Community     |                                                |
   +------------------+------------------------------------------------+
   |   64497:7:528    | Prepend once to EBGP neighbors in the          |
   |                  | Netherlands                                    |
   |   64497:7:392    | Prepend once to EBGP neighbors in Japan        |
   |   64497:7:840    | Prepend once to EBGP neighbors in United       |
   |                  | States of America                              |
   +------------------+------------------------------------------------+

   Example documentation for AS 64497 offering Action Communities deployed by AS 64497 to
   trigger prepending of
   expose a BGP traffic engineering function which selectively prepends
     the AS_PATH only with AS 64497 when propagating the route to
                      a certain all EBGP
      neighbors in the geographical region. region specified in the Parameter
                                  field.

                    Table 7: 8: Action: Prepend in Region

4.3.  Location based manipulation  Manipulation of the LOCAL_PREF

   In some cases, it can be desirable for attribute

   As part of an autonomous system agreement between AS 64497 and AS 64498, AS 64497 might
   expose BGP traffic engineering functions to AS 64498.  One such BGP
   traffic engineering function might allow
   adjacent Autonomous Systems AS 64498 to directly influence manipulate the degree
   value of
   preference associated with a route, usually expressed within the LOCAL_PREF attribute.

   Furthermore, in the case attribute of large networks spanning significant
   geography, it routes learned from AS 64498
   within AS 64497, even though the LOCAL_PREF attribute is often also useful to be able to extend this
   capability non-
   transitive and scope its effect to a geographic region.  This therefore is a
   more powerful mechanism than AS_PATH prepending, but since degree not propagated to EBGP neighbors.

   The LOCAL_PREF value of
   preference determines BGP route selection and thus onward
   advertisement, it can also be self-limiting in its scope.

   Since the LOCAL_PREF attribute which influences degree of preference
   is routes are locally significant within each autonomous system, it is not
   usually practical or useful
   Autonomous System and therefore are impossible to compare list in this
   document.  Instead, the typical LOCAL_PREF attribute values
   between autonomous systems.  Instead it can could be useful to classify the
   major types of route likely to exist within an autonomous system's
   routing classified
   as a hierarchy and provide an ability to set one's route to that
   preference:

   o  A qualified customer route.  Usually the highest preference.

   o  A peer, or network-share, route.  A co-operating network provider
      engaged in a partnership for customer coverage ("peering").

   o  A last resort, or backup route.

   It is entirely possible that some providers may have more classes of
   route preference but it is possible BGP Large Community function exposed allowing an
   EBGP neighbor to codify both the route
   preference class and affect the regional scope LOCAL_PREF value within the Local Data fields
   of specified GA.
   The following non-exhaustive list defines the Large Community attribute.

   For example, AS64497 might establish classes of routes in
   the following order of descending LOCAL_PREF value and assigns a function
   identifiers to set route preference class,
   identifier which could allow pairing
   with be used in the Function field of a location or peer-based operand to determine scope.

       +----------+-----------------------------------------------+ BGP Large
   Community.

   +----------+--------------------------------------------------------+
   | Function | Preference Class                                       |
       +----------+-----------------------------------------------+
   +----------+--------------------------------------------------------+
   |    8     | Normal customer route.                                 |    10
   | Qualified    9     | Backup customer route. Highest preference.                                 |
   |    15    10    | Peering partner. Median preference. route.                                         |
   |    19    11    | Upstream transit route.                                | Route of last resort. Lowest preference.
   |
       +----------+-----------------------------------------------+    12    | Fallback route, to be installed if no other path is    |
   |          | available.                                             |
   +----------+--------------------------------------------------------+

             Table 8: 9: Action: Preference Function Identifiers

   Once established, these route preference setting functions can be
   linked with a scoping operand such as per-peer or per-location based
   identifiers

4.3.1.  Global Manipulation of LOCAL_PREF

   AS 64497 could place one of the previously defined Preference
   Function Identifiers in order the Function field and set the value 0 in the
   Parameter field to provide AS64497's customers designate that the LOCAL_PREF associated with that
   function identifier should be applied for that route throughout the
   whole Autonomous System.

   +---------------------+---------------------------------------------+
   | BGP Large Community | Description                                 |
   +---------------------+---------------------------------------------+
   |      64497:9:0      | Assign LOCAL_PREF for a customer backup     |
   |                     | route                                       |
   |      64497:10:0     | Assign LOCAL_PREF for a
   comprehensive peering route       |
   |      64497:12:0     | Assign LOCAL_PREF for a fallback route      |
   +---------------------+---------------------------------------------+

   Example documentation for Action Communities deployed by AS 64497 to
   expose a BGP traffic engineering function which allows a BGP neighbor
   to globally manipulate the LOCAL_PREF attribute for the route within
                                 AS 64497.

             Table 10: Action: Global LOCAL_PREF Manipulation

4.3.2.  Location Based Manipulation of LOCAL_PREF

   AS 64497 could place one of the previously defined Preference
   Function Identifiers in the Function field and rich toolset use an ISO 3166-1
   numeric country identifier in the Parameter field to influence designate the
   geographical region within which the non-default LOCAL_PREF
   associated with that function identifier should be applied to the
   route.  The value of the LOCAL_PREF attribute should not deviate from
   the default for that route preference.

   +--------------------+----------------------------------------------+ class in any region not specified by one
   or more of these Action Communities.

   +--------------+----------------------------------------------------+
   |  BGP Large   | Description                                        |
   |  Community   |                                                    |
   +--------------------+----------------------------------------------+
   +--------------+----------------------------------------------------+
   |    64497:15:528 64497:9:528  | Set as peer Assign LOCAL_PREF for a customer backup route on   |
   |              | BGP speakers in the Netherlands                    |
   |    64497:19:840 64497:10:392 | Set as backup Assign LOCAL_PREF for a peering route on BGP       |
   |              | speakers in United States of Japan                                  |
   | 64497:12:840 | Assign LOCAL_PREF for a fallback route on BGP      |
   |              | speakers in United States of America               |
   +--------------------+----------------------------------------------+
   +--------------+----------------------------------------------------+

   Example documentation for Action Communities deployed by AS 64497 to
   expose a BGP traffic engineering function which allows a BGP neighbor
   to selectively manipulate the LOCAL_PREF attribute within AS 64497 in
         the geographical region specified in the Parameter field.

            Table 9: 11: Action: Regional Preference Communities

   Since the degree LOCAL_PREF Manipulation

4.3.3.  Note of preference Caution for LOCAL_PREF Functions

   The LOCAL_PREF attribute strongly influences the BGP best path selection
   (which Decision
   Process, which in turn influences onward affects the scope of route propagation) propagation.
   Therefore, Operators should take special care with when using Action
   Communities that decrease the LOCAL_PREF value, and therefore the
   degree of preference, to a value below that of another route class.
   Some of the unintended BGP states that might arise as a result of
   these traffic engineering tool such decisions are described as location
   based local preference influence (BGP Wedgies [RFC4264]). "BGP Wedgies" in
   [RFC4264].

5.  Security Considerations

   Network operators should note the recommendations in Section 11 of
   BGP Operations and Security [RFC7454].

6.  IANA Considerations

   None.

7.  Acknowledgements  Acknowledgments

   The authors would like to gratefully acknowledge the insightful
   comments, contributions, critique and support from John Heasley, Adam Chappell,
   Jonathan Stewart, and Will Hargrave.

8.  References

8.1.  Normative References

   [RFC1997]  Chandra, R., Traina, P., and T. Li, "BGP Communities
              Attribute", RFC 1997, DOI 10.17487/RFC1997, August 1996,
              <http://www.rfc-editor.org/info/rfc1997>.

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

   [RFC4264]  Griffin, T. and G. Huston, "BGP Wedgies", RFC 4264,
              DOI 10.17487/RFC4264, November 2005,
              <http://www.rfc-editor.org/info/rfc4264>.

   [RFC7454]  Durand, J., Pepelnjak, I., and G. Doering, "BGP Operations
              and Security", BCP 194, RFC 7454, DOI 10.17487/RFC7454,
              February 2015, <http://www.rfc-editor.org/info/rfc7454>.

   [RFC8092]  Heitz, J., Ed., Snijders, J., Ed., Patel, K., Bagdonas,
              I., and N. Hilliard, "BGP Large Communities Attribute",
              RFC 8092, DOI 10.17487/RFC8092, February 2017,
              <http://www.rfc-editor.org/info/rfc8092>.

8.2.  URIs

   [1] http://nanog.net

   [2] http://nlnog.net

   [3] http://unstats.un.org/unsd/methods/m49/m49regin.htm https://www.iso.org/iso-3166-country-codes.html

   [4] https://unstats.un.org/unsd/methodology/m49/

Authors' Addresses

   Job Snijders
   NTT Communications
   Theodorus Majofskistraat 100
   Amsterdam  1065 SZ
   The Netherlands

   Email: job@ntt.net
   John Heasley
   NTT Communications
   12160
   1111 NW Coleman 53rd Drive
   Portland, OR  97229  97210
   United States of America

   Email: heas@shrubbery.net

   Martijn Schmidt
   i3D.net
   Rivium 1e Straat 1
   Capelle aan den IJssel  2909 LE
   NL

   Email: martijnschmidt@i3d.net