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Point to Point VPNs Problem Statement

The information below is for an old version of the document.
Document Type This is an older version of an Internet-Draft whose latest revision is Replaced
Author Steve Hanna
Last updated 2012-03-06
Replaces draft-nir-ipsecme-p2p
Replaced by draft-ietf-ipsecme-ad-vpn-problem, RFC 7018
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IPsecME Working Group                                           S. Hanna
Internet-Draft                                                   Juniper
Intended status: Informational                             March 5, 2012
Expires: September 6, 2012

                 Point to Point VPNs Problem Statement


   This document describes the problem of enabling a large number of
   systems to communicate directly using IPsec to protect the traffic
   between them.  Manual configuration of all possible tunnels is too
   cumbersome in such cases, so an automated method is needed.

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

   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 September 6, 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
   Provisions Relating to IETF Documents
   ( in effect on the date of
   publication of this document.  Please review these documents
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   described in the Simplified BSD License.

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Table of Contents

   1.  Introduction . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1.  Terminology  . . . . . . . . . . . . . . . . . . . . . . .  3
     1.2.  Conventions Used in This Document  . . . . . . . . . . . .  3
   2.  Use Cases  . . . . . . . . . . . . . . . . . . . . . . . . . .  4
     2.1.  Endpoint-to-Endpoint P2P VPN Use Case  . . . . . . . . . .  4
     2.2.  Gateway-to-Gateway P2P VPN Use Case  . . . . . . . . . . .  4
     2.3.  Endpoint-to-Gateway P2P VPN Use Case . . . . . . . . . . .  4
   3.  Inadequacy of Existing Solutions . . . . . . . . . . . . . . .  6
     3.1.  Exhaustive Configuration . . . . . . . . . . . . . . . . .  6
     3.2.  Star Topology  . . . . . . . . . . . . . . . . . . . . . .  6
     3.3.  Proprietary Approaches . . . . . . . . . . . . . . . . . .  7
   4.  Requirements . . . . . . . . . . . . . . . . . . . . . . . . .  8
   5.  Security Considerations  . . . . . . . . . . . . . . . . . . .  9
   6.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . . 10
   7.  Acknowledgements . . . . . . . . . . . . . . . . . . . . . . . 11
   8.  Normative References . . . . . . . . . . . . . . . . . . . . . 12
   Author's Address . . . . . . . . . . . . . . . . . . . . . . . . . 13

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1.  Introduction

   IPsec [RFC4301] is used in several different cases, including tunnel-
   mode site-to-site VPNs and Remote Access VPNs.  Host to host
   communication employing transport mode also exists, but is far less
   commonly deployed.

   The subject of this document is the problem presented by large scale
   deployments of IPsec.  These may be a large collection of VPN
   gateways connecting various sites, a large number of remote endpoints
   connecting to a number of gateways or to each other, or a mix of the
   two.  The gateways and endpoints may belong to a single
   administrative domain or several domains with a trust relationship.

   Section 4.4 of RFC 4301 describes the major IPsec databases needed
   for IPsec processing.  It requires an extensive configuration for
   each tunnel, so manually configuring a system of many gateways and
   endpoints becomes infeasible and inflexible.

   The difficulty is that all the configuration mentioned in RFC 4301 is
   not superfluous.  IKE implementations need to know the identity and
   credentials of all possible peer systems, as well as the addresses of
   hosts and/or networks behind them.  A simplified mechanism for
   dynamically establishing point-to-point tunnels is needed.  Section 2
   contains several use cases that motivate this effort.

1.1.  Terminology

   Endpoint - A host that implements IPsec for its own traffic but does
   not act as a gateway.

   Gateway - A network device that implements IPsec to protect traffic
   flowing through the device.

   Point-to-Point - Direct communication between two parties without
   active participation (e.g. encryption or decryption) by any other

   Security Association (SA) - Defined in [RFC4301].

1.2.  Conventions Used in This Document

   The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
   document are to be interpreted as described in [RFC2119].

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2.  Use Cases

   This section presents the key use cases for large-scale point-to-
   point VPN.

   In all of these use cases, the participants (endpoints and gateways)
   may be from a single organization or from multiple organizations with
   an established trust relationship.  When multiple organizations are
   involved, products from multiple vendors are employed so open
   standards are needed to provide interoperability.  Establishing
   communications between participants with no established trust
   relationship is out of scope for this effort.

2.1.  Endpoint-to-Endpoint P2P VPN Use Case

   Two endpoints wish to communicate securely via a direct, point-to-
   point SA.

   The need for secure endpoint to endpoint communications is often
   driven by a need to employ high-bandwidth, low latency local
   connectivity instead of using slow, expensive links to remote
   gateways.  For example, two users in close proximity may wish to
   place a direct, secure video or voice call without needing to send
   the call through remote gateways, which would add latency to the
   call, consume precious remote bandwidth, and increase overall costs.

2.2.  Gateway-to-Gateway P2P VPN Use Case

   Two gateways suddenly need to exchange a lot of data.

   For example, a mobile worker from one government agency may sit down
   in a shared remote office and start up his VOIP or video phone
   software.  He should rapidly get an efficient, secure, low latency
   connection to his voice mail system and to anyone that he might call.
   This user, his voice mail system, and other people that he calls will
   probably be operating behind gateways but those gateways may have
   little advance warning of the need to establish secure connectivity
   between them.

2.3.  Endpoint-to-Gateway P2P VPN Use Case

   An endpoint wants to connect directly to the most efficient gateway
   for accessing a particular service.

   For example, a mobile user roaming on the Internet may need to open a
   remote desktop connection to a virtual machine hosted on a particular
   server or to a service provided by a variety of servers distributed
   around the globe.  The user should be able to establish a connection

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   directly to the gateway closest to the service desired.  If multiple
   gateways can suffice, load balancing and failover across gateways may
   be useful.

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3.  Inadequacy of Existing Solutions

   Several solutions exist for the problems described above.  However,
   none of these solutions is adequate, as described here.

3.1.  Exhaustive Configuration

   One simple solution is to configure all gateways and endpoints in
   advance with all the information needed to determine which gateway or
   endpoint is optimal and to establish an SA with that gateway or
   endpoint.  However, this solution does not scale in a large network
   with hundreds of thousands of gateways and endpoints, especially when
   multiple organizations are involved and things are rapidly changing
   (e.g. mobile endpoints).  A more dynamic system for securely and
   scalably establishing SAs between gateways is needed.

3.2.  Star Topology

   The most common way to address this problem today is to use what has
   been termed a "star topology".  In this case one or a few gateways
   are defined as "core gateways", while the rest of the systems
   (whether endpoints or gateways) are defined as "satellites".  The
   satellites never connect to other satellites.  They only open tunnels
   with the core gateways.

   For a large number of gateways in one administrative domain, one
   gateway may be defined as the core, and the rest of the gateways and
   remote access clients connect only to that gateway.  If the packet
   destination is behind another gateway, then the core gateway will re-
   encrypt the traffic, and send it through the other tunnel.  If we
   have two collections of gateways under two administrative domains,
   then each domain has its own core, and the administrators only need
   to define an IPsec tunnel between the two cores.  This tunnel is
   often referred to as a "trunk".

   One problem with stars and trunks is that it creates a high load on
   the core gateways as well as on the trunk connection.  This load is
   both in processing power and in network bandwidth.  A single packet
   in the trunk scenario can be encrypted and decrypted three times.  It
   would be much preferable if these gateways and clients could initiate
   tunnels between them, bypassing the core gateways.  Additionally, the
   path bandwidth to these core gateways may be lower than that of the
   path between the satellites.  For example, two remote access users
   may be in the same building with high-speed wifi (for example, at an
   IETF meeting).  Channeling their conversation through the core
   gateways of their respective employers seems extremely wasteful, as
   well as having lower bandwidth.

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   The challenge is how to build large scale, fully meshed IPsec
   protected networks that can dynamically change with minimum
   administrative overhead.

3.3.  Proprietary Approaches

   Several vendors offer proprietary solutions to these problems.
   However, these solutions offer no interoperability between equipment
   from one vendor and another.  This means that they are generally
   restricted to use within one organization.  Multiple organizations
   cannot be expected to all choose the same equipment vendor.

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4.  Requirements

   This section will be completed when the use cases are agreed upon.

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5.  Security Considerations

   The solution to the problems presented in this draft may involve
   dynamic updates to databases defined by RFC 4301, such as the
   Security Policy Database (SPD) or the Peer Authorization Database

   RFC 4301 is silent about the way these databases are populated, and
   it is implied that these databases are static and pre-configured by a
   human.  Allowing dynamic updates to these databases must be thought
   out carefully, because it allows the protocol to alter the security
   policy that the IPsec endpoints implement.

   One obvious attack to watch out for is stealing traffic to a
   particular site.  The IP address for is
   If we add an entry to an IPsec endpoint's SPD that says that traffic
   to is protected through peer Gw-Mallory, then this allows
   Gw-Mallory to either pretend to be or to proxy and
   read all traffic to that site.  Updates to this database requires a
   clear trust model.

   More to be added.

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6.  IANA Considerations

   No actions are required from IANA for this informational document.

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7.  Acknowledgements

   Many people have contributed to the development of this problem
   statement and many more will probably do so before we are done with
   it.  While we cannot thank all contributors, some have played an
   especially prominent role.  Yoav Nir, Jorge Coronel Mendoza, Chris
   Ulliott, and John Veizades wrote the document upon which this draft
   was based.  Geoffrey Huang, Suresh Melam, Praveen Sathyanarayan,
   Andreas Steffen, and Brian Weis provided essential input.

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8.  Normative References

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

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

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Author's Address

   Steve Hanna
   Juniper Networks, Inc.
   1194 N. Mathilda Ave.
   Sunnyvale, CA  94089


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