Network Working Group                                    F. Templin, Ed.
Internet-Draft                              Boeing Research & Technology
Intended status: Informational                            March 13, 2017
Expires: September 14, 2017

     A Simple BGP-based Mobile Routing System for the Aeronautical
                       Telecommunications Network


   The International Civil Aviation Organization (ICAO) is investigating
   mobile routing solutions for a worldwide Aeronautical
   Telecommunications Network with Internet Protocol Services (ATN/IPS).
   The ATN/IPS will eventually replace existing communication services
   with an IPv6-based service supporting pervasive Air Traffic
   Management (ATM) for Air Traffic Controllers (ATC), Airline
   Operations Controllers (AOC), and all commercial aircraft worldwide.
   This informational document describes a simple mobile routing service
   based on mature industry standards to address the ATN/IPS

Status of This Memo

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   This Internet-Draft will expire on September 14, 2017.

Copyright Notice

   Copyright (c) 2017 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
   ( in effect on the date of

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   publication of this document.  Please review these documents
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Table of Contents

   1.  Introduction  . . . . . . . . . . . . . . . . . . . . . . . .   2
   2.  Proposed BGP-based ATN/IPS Routing System . . . . . . . . . .   4
   3.  Route Optimization  . . . . . . . . . . . . . . . . . . . . .   7
   4.  Route Availability  . . . . . . . . . . . . . . . . . . . . .   9
   5.  BGP Protocol Considerations . . . . . . . . . . . . . . . . .  10
   6.  Implementation Status . . . . . . . . . . . . . . . . . . . .  10
   7.  IANA Considerations . . . . . . . . . . . . . . . . . . . . .  10
   8.  Security Considerations . . . . . . . . . . . . . . . . . . .  11
   9.  Related Work  . . . . . . . . . . . . . . . . . . . . . . . .  11
   10. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . .  11
   11. References  . . . . . . . . . . . . . . . . . . . . . . . . .  11
     11.1.  Normative References . . . . . . . . . . . . . . . . . .  12
     11.2.  Informative References . . . . . . . . . . . . . . . . .  12
   Author's Address  . . . . . . . . . . . . . . . . . . . . . . . .  14

1.  Introduction

   The International Civil Aviation Organization [ICAO] is investigating
   mobile routing solutions for a worldwide Aeronautical
   Telecommunications Network with Internet Protocol Services (ATN/IPS).
   The ATN/IPS will eventually replace existing communication services
   with an IPv6-based service supporting pervasive Air Traffic
   Management (ATM) for Air Traffic Controllers (ATC), Airline
   Operations Controllers (AOC), and all commercial aircraft worldwide.
   This informational document describes a simple mobile routing service
   based on mature industry standards to address the ATN/IPS

   Aircraft communicate via wireless aviation data links that typically
   support much lower data rates than terrestrial wireless and wired-
   line communications.  For example, VHF-based data links only support
   data rates on the order of 32Kbps and an emerging L-Band data link
   that is expected to play a key role in future aeronautical
   communications only supports rates on the order of 1Mbps.  Although
   satellite data links can provide much higher data rates during
   optimal conditions, they (like all other aviation data links) are
   subject to errors, delay, disruption, signal intermittence,
   degradation due to atmospheric conditions, etc.  The well-connected
   ground domain ATN/IPS network should therefore treat each safety-of-

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   flight critical packet produced by (or destined to) an aircraft as a
   precious commodity and strive for a "better-than-best-effort" service
   that provides the highest possible degree of reliability.

   The ATN/IPS assumes a worldwide connected Internetwork for carrying
   ATM communications.  The Internetwork could be manifested as a
   private collection of long-haul backbone links (e.g., fiberoptics,
   copper, SATCOM, etc.) interconnected by high-performance networking
   gear such as bridges, switches and routers.  Such a private
   Internetwork would need to connect all ATN/IPS participants
   worldwide, and could therefore present a considerable cost for a
   large-scale deployment of new infrastructure.  Alternatively, the
   ATN/IPS could be deployed as an overlay over the existing global
   public Internet itself as long as sufficient security and reliability
   provisions are met.

   The ATN/IPS further assumes that each aircraft will receive an IPv6
   Mobile Network Prefix (MNP) that accompanies the aircraft wherever it
   travels.  ATCs and AOCs will likewise receive IPv6 prefixes, but they
   would typically appear in static (not mobile) deployments.
   Throughout the rest of this document, we therefore use the term "MNP"
   when discussing an IPv6 prefix that is delegated to any ATN/IPS end
   system, including ATCs, AOCs and aircraft.  We also use the term
   Mobility Service Prefix (MSP) to refer to an aggregated prefix
   assigned to the ATN/IPS by an Internet assigned numbers authority,
   and from which all MNPs are delegated (e.g., up to 2**32 IPv6 /64
   MNPs could be delegated from the MSP 2001:db8::/32).

   [CBB] describes an aviation mobile routing service based on dynamic
   updates in the global public Internet Border Gateway Protocol (BGP)
   [RFC4271] routing system.  Practical experience with the approach has
   shown that frequent injections and withdrawals of MNPs in the
   Internet routing system results in excessive BGP update messaging,
   slow routing table convergence times, and extended outages when no
   route is available.  This is due to both conservative default BGP
   protocol timing parameters (see Section 5) and the complex peering
   interconnections of BGP routers within the global Internet
   infrastructure.  The situation is further exacerbated by frequent
   aircraft mobility events that each result in BGP updates that must be
   propagated to all BGP routers in the Internet that carry a full
   routing table.

   We therefore consider a new approach using a BGP overlay network
   routing system where a private BGP routing protocol instance is
   maintained between ATN/IPS Autonomous System (AS) Border Routers
   (ASBRs).  The private BGP instance does not interact with the
   Internetwork BGP routing system, and BGP updates are unidirectional

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   from "stub" ASBRs (s-ASBRs) to a very small set of "core" ASBRs
   (c-ASBRs) in a hub-and-spokes arrangement.

   The s-ASBRs for each stub AS connect to a small number of c-ASBRs via
   dedicated high speed links and/or tunnels across the Internetwork
   using industry-standard encapsulations (e.g., Generic Routing
   Encapsulation (GRE) [RFC2784], IPsec [RFC4301] etc.).  The s-ASBRs
   engage in external BGP (eBGP) peerings with their respective c-ASBRs,
   and only maintain routing table entries for the MNPs currently active
   within the stub AS.  A stub AS may connect to the core via multiple
   s-ASBRs, in which case the s-ASBRs would engage in internal BGP
   (iBGP) peerings among themselves to maintain a common view of the
   stub AS MNPs.  Finally, the s-ASBRs also maintain default routes with
   their c-ASBRs as the next hop, and therefore hold only partial
   topology information.

   The c-ASBRs connect to other c-ASBRs using iBGP peerings over which
   they collaboratively maintain a full routing table for all active
   MNPs currently in service.  Therefore, only the c-ASBRs maintain a
   full BGP routing table and never send any BGP updates to s-ASBRs.
   This simple arrangement therefore greatly reduces the number of BGP
   updates that need to be synchronized among peers, and the number is
   reduced further still when localized mobility events within stub ASes
   (i.e., "intradomain" mobility events) are mitigated within the AS
   instead of being propagated to the core.

   The following section provides a detailed discussion of the proposed
   BGP-based ATN/IPS routing system.

2.  Proposed BGP-based ATN/IPS Routing System

   The proposed ATN/IPS routing system comprises a private BGP instance
   coordinated between ASBRs in an overlay network.  The overlay does
   not interact with the native Internetwork BGP routing system, and
   each c-ASBR advertises only a small and unchanging set of MSPs into
   the Internetwork instead of the full dynamically changing set of

   In a reference deployment, one or more s-ASBRs connect each stub AS
   to the overlay using a shared stub AS Number (ASN).  Each s-ASBR
   further uses eBGP to peer with one or more c-ASBRs.  All c-ASBRs are
   members of the same core AS, and use a shared core ASN.  The c-ASBRs
   further use iBGP to maintain a synchronized consistent view of all
   active MNPs currently in service.  Figure 1 below represents the
   reference deployment.  Note that in the figure only two s-ASBRs show
   detail, but similar arrangements are implied for all other s-ASBRs.
   Note also that each stub AS shows only a single s-ASBR with a single
   c-ASBR connection, but in practical deployments each stub AS may have

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   multiple s-ASBRs that peer with each other via iBGP and also peer
   with multiple c-ASBRs via eBGP, e.g., for fault tolerance.

   .                                                             .
   .               (:::)-.  <- Stub ASes ->  (:::)-.             .
   .   MNPs-> .-(:::::::::)             .-(:::::::::) <-MNPs     .
   .            `-(::::)-'                `-(::::)-'             .
   .             +-------+                +-------+              .
   .             |s-ASBR1|                |s-ASBR2|              .
   .             +--+----+                +-----+-+              .
   .                 \                         /                 .
   .                  \eBGP                   /eBGP              .
   .                   \                     /                   .
   .                    +-------+   +-------+                    .
   .          eBGP+-----+c-ASBR1|   +c-ASBR2+-----+eBGP          .
   .   +-------+ /      +--+----+   +-----+-+      \ +-------+   .
   .   |s-ASBRn+/       iBGP\   (:::)-.  /iBGP      \+s-ASBR3|   .
   .   +-------+            .-(::::::::)             +-------+   .
   .       .            .-(::::::::::::::)-.                     .
   .       .           (::::  Core AS   :::)                     .
   .   +-------+         `-(:::::::::::::)-'         +-------+   .
   .   |s-ASBR7+\      iBGP/`-(:::::::-'\iBGP       /+s-ASBR4|   .
   .   +-------+ \      +-+-----+   +----+--+      / +-------+   .
   .          eBGP+-----+c-ASBRn|   |c-ASBR3+-----+eBGP          .
   .                    +-------+   +-------+                    .
   .                   /                     \                   .
   .                  /eBGP                   \eBGP              .
   .                 /                         \                 .
   .            +---+---+                 +-----+-+              .
   .            |s-ASBR6|                 |s-ASBR5|              .
   .            +-------+                 +-------+              .
   .                                                             .
   .                                                             .
   .   <------------------- Internetwork -------------------->   .

                      Figure 1: Reference Deployment

   In the reference deployment, each s-ASBR maintains routes for active
   MNPs that currently belong to its stub AS, and dynamically announces
   new MNPs and withdraws departed MNPs in its eBGP updates to c-ASBRs
   in response to "interdomain" mobility events.  Since ATN/IPS end
   systems are expected to remain within the same stub AS for extended
   timeframes, however, intradomain mobility events (such as an aircraft
   handing off between cell towers) are handled locally within the stub
   AS instead of being propagated as interdomain eBGP updates.

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   Each c-ASBR configures a black-hole route for each of its MSPs.  By
   black-holing the MSPs, the c-ASBR will maintain forwarding table
   entries only for the MNPs that are currently active, and packets
   destined to all other MNPs will correctly incur ICMPv6 Destination
   Unreachable messages [RFC4443] due to the black hole route.  The
   c-ASBRs do not send eBGP updates for MNPs to s-ASBRs, but instead
   originate a default route.  In this way, s-ASBRs have only partial
   topology knowledge (i.e., they know only about the active MNPs
   currently within their stub ASes) and they forward all other packets
   to c-ASBRs which have full topology knowledge.

   Scaling properties of this ATN/IPS routing system are limited by the
   number of BGP routes that can be carried by the c-ASBRs.  A 2015
   study showed that BGP routers in the global public Internet at that
   time carried more than 500K routes with linear growth and no signs of
   router resource exhaustion [BGP].  A more recent network emulation
   study also showed that a single c-ASBR can accommodate at least 1M
   dynamically changing BGP routes even on a lightweight virtual
   machine, with the expectation that high-performance dedicated router
   hardware can support even more.

   Therefore, assuming each c-ASBR can carry 1M or more routes, this
   means that at least 1M ATN/IPS end system MNPs can be serviced by a
   single set of c-ASBRs.  A means of increasing scaling would be to
   assign a different set of c-ASBRs for each set of MSPs.  In that
   case, each s-ASBR still peers with one or more c-ASBRs from each set
   of c-ASBRs, but the s-ASBR institutes route filters so that it only
   sends BGP updates to the specific set of c-ASBRs that aggregate the
   MSP.  For example, if the MSP for the ATN/IPS deployment is
   2001:db8::/32, a first set of c-ASBRs could service the MSP segment
   2001:db8::/40, a second set could service 2001:db8:0100::/40, a third
   set could service 2001:db8:0200::/40, etc.

   Assuming up to 1K sets of c-ASBRs, the ATN/IPS routing system can
   then accommodate 1B or more MNPs.  In this way, each set of c-ASBRs
   services a specific set of MSPs that they advertise to the native
   Internetwork routing system, and each s-ASBR configures MSP-specific
   routes that list the correct set of c-ASBRs as next hops.  This
   arrangement also allows for natural incremental deployment, and can
   support small scale initial deployments followed by dynamic
   deployment of additional ATN/IPS infrastructure elements without
   disturbing the already-deployed base.

   Finally, c-ASBRs may have multiple routing table entries for a single
   MNP advertised by multiple s-ASBRs.  Each s-ASBR can advertise a
   MULTI_EXIT_DISC (MED) metric for routes that it originates in its
   eBGP peering configurations [RFC4451] so that c-ASBRs can determine
   preferences for MNPs learned from multiple s-ASBRs.  In this way,

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   c-ASBRs can select the neighboring s-ASBR with the lowest MED value,
   i.e., even if it is not on the shortest path.  The c-ASBR can then
   fail over to a s-ASBR with a larger MED value in case of MNP
   withdrawal or s-ASBR failure.  Such an event could correspond to an
   aviation data link handover, e.g., when an aircraft switches over
   from a satellite link to an L-Band link.

3.  Route Optimization

   ATN/IPS end systems will frequently need to communicate with
   correspondents located in other stub ASes.  In the ASBR peering
   arrangement discussed in Section 2, this can initially only be
   accommodated by having the source s-ASBR forward packets to a c-ASBR
   which then forwards the packets toward the destination s-ASBR where
   the destination ATN/IPS end system resides.  In many cases, it would
   be desirable to eliminate c-ASBRs from this "dogleg" route so that
   the source s-ASBR can send packets directly to the destination s-ASBR
   through tunneling across the Internetwork.  This can be accomplished
   using a route optimization service based on the IPv6 Neighbor
   Discovery Redirect function [RFC4861][RFC6706][I-D.templin-aerolink][

   A route optimization example is shown in Figure 2 and Figure 3 below.
   In the first figure, the dogleg route between correspondents in the
   stub ASes traverses the path from s-ASBR1 to c-ASBR1 to c-ASBR2 to
   S-ASBR2.  In the second figure, the optimized route goes directly
   from s-ASBR1 to s-ASBR2, i.e., the c-ASBRs are not included in the

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   .                                                             .
   .               (:::)-.  <- Stub ASes ->  (:::)-.             .
   .   MNPs-> .-(:::::::::)             .-(:::::::::) <-MNPs     .
   .            `-(::::)-'                `-(::::)-'             .
   .             +-------+                +-------+              .
   .             |s-ASBR1|                |s-ASBR2|              .
   .             +--+--^^+                +^^---+-+              .
   .                 \  \\     Dogleg     //   /                 .
   .              eBGP\  \\    Route     //   /eBGP              .
   .                   \  \\============//   /                   .
   .                    +-------+   +-------+                    .
   .                    +c-ASBR1|   +c-ASBR2+                    .
   .                    +--+----+   +-----+-+                    .
   .                       +--------------+                      .
   .                             iBGP                            .
   .                                                             .
   .   <------------------- Internetwork -------------------->   .

                Figure 2: Dogleg Route Before Optimization

   .                                                             .
   .               (:::)-.  <- Stub ASes ->  (:::)-.             .
   .   MNPs-> .-(:::::::::)             .-(:::::::::) <-MNPs     .
   .            `-(::::)-'                `-(::::)-'             .
   .             +-------+     Direct     +-------+              .
   .             |s-ASBR1<================>s-ASBR2|              .
   .             +--+----+     Route      +-----+-+              .
   .                 \                         /                 .
   .              eBGP\                       /eBGP              .
   .                   \                     /                   .
   .                    +-------+   +-------+                    .
   .                    +c-ASBR1|   +c-ASBR2+                    .
   .                    +--+----+   +-----+-+                    .
   .                       +--------------+                      .
   .                             iBGP                            .
   .                                                             .
   .   <------------------- Internetwork -------------------->   .

               Figure 3: Direct Route Following Optimization

   It is very important to understand that route optimization can fail
   if the source s-ASBR cannot tunnel packets directly to the
   destination s-ASBR due to some form of Internetwork blockage such as
   filtering middleboxes.  It is also necessary for the source s-ASBR to

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   quickly detect and adjust to failure of the destination s-ASBR.  In
   both of these cases, significant packet loss could occur before the
   source s-ASBR can detect that the route-optimized path has failed.
   This implies that route optimized paths may not always be the best
   choice for carrying safety-of-flight critical packets with high
   reliability requirements.

4.  Route Availability

   In the ATN/IPS BGP-based routing system proposed in this document,
   each s-ASBR always has a default route and can therefore always send
   packets via the dogleg route through a c-ASBR even if a route
   optimized path has been established.  The direct paths between
   s-ASBRs and c-ASBRs are maintained by BGP peering session keepalives
   such that, if a link or an ASBR goes down, BGP will detect the
   failure and readjust the routing tables.  However, ASBRs and the
   links that interconnect them are expected to be secured as highly-
   available and fault tolerant critical infrastructure such that
   peering session failures should be extremely rare.

   This represents a distinct architectural difference from other
   approaches that only operate over route optimized paths.  With the
   approach described herein the source s-ASBR will always have a
   working route, even if only via a dogleg path through a c-ASBR.  This
   gives rise to the possibility of sending {high-priority, low-data-
   rate} packets via the assured dogleg route and {low-priority, high-
   data-rate} packets via the optimized route, e.g., based on per-packet
   quality of service indications.  This could also give rise to a fair
   pricing model that would charge more for the use of the high-
   assurance dogleg path and less for the use of the lesser-assured
   route-optimized path.

   This distinction is of vital importance to aviation networking, where
   isolated safety-of-flight critical packets such as produced by the
   Controller Pilot Data Link Communications (CPDLC) facility may not be
   eligible for retransmission, e.g., if an aviation data link is
   failing.  If there is no route available, the packet can be dropped
   or delayed and safety-of-flight parameters could be lost.  Even when
   an optimized route is discovered on-demand, the route may not work
   and again safety-of-flight critical packets could be lost.

   In summary, the approach proposed in this document is a proactive
   routing protocol that ensures that at least one working route will
   always be available.  This is in contrast to on-demand routing
   protocols that must either drop or delay safety-of-flight critical
   packets when there is no route available.

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5.  BGP Protocol Considerations

   The number of eBGP peering sessions that each c-ASBR must service is
   proportional to the number of s-ASBRs in the system.  Network
   emulations with lightweight virtual machines have shown that a single
   c-ASBR can service at least 100 eBGP peerings from s-ASBRs that each
   advertise 10K MNP routes (i.e., 1M total).  It is expected that
   robust c-ASBRs can service many more peerings than this - possibly by
   multiple orders of magnitude.  But even assuming a conservative
   limit, the number of s-ASBRs could be increased by also increasing
   the number of c-ASBRs.  Since c-ASBRs also peer with each other using
   iBGP, however, larger-scale c-ASBR deployments may need to employ an
   adjunct facility such as BGP route reflectors [RFC4456].

   Industry standard BGP routers provide configurable parameters with
   conservative default values.  For example, the default hold time is
   90 seconds, the default keepalive time is 1/3 of the hold time, and
   the default MinRouteAdvertisementinterval is 30 seconds for eBGP
   peers and 5 seconds for iBGP peers (see Section 10 of [RFC4271]).
   For the simple mobile routing system described herein, these
   parameters can and should be set to more aggressive values to support
   faster neighbor/link failure detection and faster routing protocol
   convergence times.  For example, a hold time of 3 seconds and a
   MinRouteAdvertisementinterval of 0 seconds for both iBGP and eBGP.

   By default, MED only compares metrics that originate from multiple
   neighbors within the same AS [RFC4451].  In order to compare MED
   metrics that come from different ASes, a router configuration file
   entry may be needed (e.g., Cisco routers require the configuration
   file entry "bgp always-compare-med").  Furthermore, in order for the
   MED discriminator to be applied correctly, the AS_PATH phase in the
   BGP route selection process must be disabled (e.g., Cisco routers use
   the configuration file entry "bgp bestpath as-path ignore").

6.  Implementation Status

   The BGP routing arrangement described in this document has been
   prototyped in network emulations showing that at least 1 million MNPs
   can be propagated to each c-ASBR even on lightweight virtual

7.  IANA Considerations

   This document does not introduce any IANA considerations.

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8.  Security Considerations

   ATN/IPS ASBRs on the open Internet are susceptible to the same attack
   profiles as for any Internet nodes.  For this reason, ASBRs should
   employ physical security and/or IP securing mechanisms such as IPsec
   [RFC4301], TLS [RFC5246], etc.

   ATN/IPS ASBRs present targets for Distributed Denial of Service
   (DDoS) attacks.  This concern is no different than for any node on
   the open Internet, where attackers could send spoofed packets to the
   node at high data rates.  This can be mitigated by connecting ATN/IPS
   ASBRs over dedicated links with no connections to the Internet and/or
   when ASBR connections to the Internet are only permitted through
   well-managed firewalls.

   ATN/IPS s-ASBRs should institute rate limits to protect low data rate
   aviation data links from receiving DDoS packet floods.

9.  Related Work

   This work has evolved from the author's earlier publications,

   SEAL: [RFC5320][I-D.templin-intarea-seal].

   VET: [RFC5558][I-D.templin-intarea-vet].

   IRON: [RFC6179][I-D.templin-ironbis].

   AERO: [RFC6706][I-D.templin-aerolink][I-D.templin-6man-rio-redirect].

10.  Acknowledgements

   This work is aligned with the FAA as per the SE2025 contract number

   This work is aligned with the NASA Safe Autonomous Systems Operation
   (SASO) program under NASA contract number NNA16BD84C.

   This work is aligned with the Boeing Information Technology (BIT)
   MobileNet program.

11.  References

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11.1.  Normative References

   [RFC0791]  Postel, J., "Internet Protocol", STD 5, RFC 791,
              DOI 10.17487/RFC0791, September 1981,

   [RFC2460]  Deering, S. and R. Hinden, "Internet Protocol, Version 6
              (IPv6) Specification", RFC 2460, DOI 10.17487/RFC2460,
              December 1998, <>.

   [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,

   [RFC4443]  Conta, A., Deering, S., and M. Gupta, Ed., "Internet
              Control Message Protocol (ICMPv6) for the Internet
              Protocol Version 6 (IPv6) Specification", RFC 4443,
              DOI 10.17487/RFC4443, March 2006,

   [RFC4451]  McPherson, D. and V. Gill, "BGP MULTI_EXIT_DISC (MED)
              Considerations", RFC 4451, DOI 10.17487/RFC4451, March
              2006, <>.

   [RFC4456]  Bates, T., Chen, E., and R. Chandra, "BGP Route
              Reflection: An Alternative to Full Mesh Internal BGP
              (IBGP)", RFC 4456, DOI 10.17487/RFC4456, April 2006,

   [RFC4861]  Narten, T., Nordmark, E., Simpson, W., and H. Soliman,
              "Neighbor Discovery for IP version 6 (IPv6)", RFC 4861,
              DOI 10.17487/RFC4861, September 2007,

11.2.  Informative References

   [BGP]      Huston, G., "BGP in 2015,", January

   [CBB]      Dul, A., "Global IP Network Mobility using Border Gateway
              Protocol (BGP),
              Global_IP_Network_Mobility_using_BGP.pdf", March 2006.

              Templin, F. and j. woodyatt, "Route Information Options in
              Redirect Messages", draft-templin-6man-rio-redirect-01
              (work in progress), January 2017.

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Internet-Draft               BGP for ATN/IPS                  March 2017

              Templin, F., "Asymmetric Extended Route Optimization
              (AERO)", draft-templin-aerolink-74 (work in progress),
              November 2016.

              Templin, F., "The Subnetwork Encapsulation and Adaptation
              Layer (SEAL)", draft-templin-intarea-seal-68 (work in
              progress), January 2014.

              Templin, F., "Virtual Enterprise Traversal (VET)", draft-
              templin-intarea-vet-40 (work in progress), May 2013.

              Templin, F., "The Interior Routing Overlay Network
              (IRON)", draft-templin-ironbis-16 (work in progress),
              March 2014.

   [ICAO]     ICAO, I., "",
              February 2017.

   [RFC2784]  Farinacci, D., Li, T., Hanks, S., Meyer, D., and P.
              Traina, "Generic Routing Encapsulation (GRE)", RFC 2784,
              DOI 10.17487/RFC2784, March 2000,

   [RFC4301]  Kent, S. and K. Seo, "Security Architecture for the
              Internet Protocol", RFC 4301, DOI 10.17487/RFC4301,
              December 2005, <>.

   [RFC5246]  Dierks, T. and E. Rescorla, "The Transport Layer Security
              (TLS) Protocol Version 1.2", RFC 5246,
              DOI 10.17487/RFC5246, August 2008,

   [RFC5320]  Templin, F., Ed., "The Subnetwork Encapsulation and
              Adaptation Layer (SEAL)", RFC 5320, DOI 10.17487/RFC5320,
              February 2010, <>.

   [RFC5558]  Templin, F., Ed., "Virtual Enterprise Traversal (VET)",
              RFC 5558, DOI 10.17487/RFC5558, February 2010,

   [RFC6179]  Templin, F., Ed., "The Internet Routing Overlay Network
              (IRON)", RFC 6179, DOI 10.17487/RFC6179, March 2011,

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Internet-Draft               BGP for ATN/IPS                  March 2017

   [RFC6706]  Templin, F., Ed., "Asymmetric Extended Route Optimization
              (AERO)", RFC 6706, DOI 10.17487/RFC6706, August 2012,

Author's Address

   Fred L. Templin (editor)
   Boeing Research & Technology
   P.O. Box 3707
   Seattle, WA  98124


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