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Versions: (draft-fang-mpls-tp-security-framework) 00 01 02 03 04 05 06 07 08 09 RFC 6941

INTERNET-DRAFT                                              L. Fang, Ed.
Intended Status: Informational                                     Cisco
Expires: August 25, 2013                           B. Niven-Jenkins, Ed.
                                                                 Velocix
                                                       S. Mansfield, Ed.
                                                                Ericsson
                                                        R. Graveman, Ed.
                                                            RFG Security

                                                       February 25, 2013


                      MPLS-TP Security Framework
                draft-ietf-mpls-tp-security-framework-09

Abstract

   This document provides a security framework for Multiprotocol Label
   Switching Transport Profile (MPLS-TP). MPLS-TP extends MPLS
   technologies and introduces new OAM capabilities, a transport-
   oriented path protection mechanism, and strong emphasis on static
   provisioning supported by network management systems. This document
   addresses the security aspects relevant in the context of MPLS-TP
   specifically. It describes potential security threats, security
   requirements for MPLS-TP, and mitigation procedures for MPLS-TP
   networks and MPLS-TP interconnection to other MPLS and GMPLS
   networks. This document is built on RFC5920 "MPLS and GMPLS security
   framework" by providing additional security considerations which are
   applicable to the MPLS-TP extensions. All the security considerations
   from RFC5920 are assumed to apply.

   This document is a product of a joint Internet Engineering Task Force
   (IETF) / International Telecommunication Union Telecommunication
   Standardization Sector (ITU-T) effort to include an MPLS Transport
   Profile within the IETF MPLS and PWE3 architectures to support the
   capabilities and functionality of a packet transport network.

Status of this Memo

   This Internet-Draft is submitted to IETF in full conformance with the
   provisions of BCP 78 and BCP 79.

   Internet-Drafts are working documents of the Internet Engineering
   Task Force (IETF), its areas, and its working groups.  Note that
   other groups may also distribute working documents as
   Internet-Drafts.

   Internet-Drafts are draft documents valid for a maximum of six months



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   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."

   The list of current Internet-Drafts can be accessed at
   http://www.ietf.org/1id-abstracts.html

   The list of Internet-Draft Shadow Directories can be accessed at
   http://www.ietf.org/shadow.html


Copyright and License Notice

   Copyright (c) 2013 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
   described in the Simplified BSD License.


Table of Contents

   1. Introduction  . . . . . . . . . . . . . . . . . . . . . . . . .  3
     1.1. Terminology . . . . . . . . . . . . . . . . . . . . . . . .  3
   2. Security Reference Models . . . . . . . . . . . . . . . . . . .  4
     2.1. Security Reference Model 1  . . . . . . . . . . . . . . . .  4
     2.2. Security Reference Model 2  . . . . . . . . . . . . . . . .  6
   3. Security Threats  . . . . . . . . . . . . . . . . . . . . . . .  8
   4. Defensive Techniques  . . . . . . . . . . . . . . . . . . . . .  9
   5. Security Considerations . . . . . . . . . . . . . . . . . . . . 10
   6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 11
   7. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 11
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 11
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 11
     8.2. Informative References  . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12
   Contributors' Addresses  . . . . . . . . . . . . . . . . . . . . . 12







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1. Introduction

   This document provides a security framework for Multiprotocol Label
   Switching Transport Profile (MPLS-TP).

   As defined in MPLS-TP Requirements [RFC5654] and MPLS-TP Framework
   [RFC5921], MPLS-TP uses a subset of MPLS features and introduces
   extensions to reflect the characteristics of the transport
   technology. The additional functionality include in-band OAM,
   transport-oriented path protection and recovery mechanisms, and new
   OAM capabilities developed for MPLS-TP but apply to general MPLS and
   GMPLS. There is strong emphasis in MPLS-TP on static provisioning
   support through network management systems (NMS) or Operation Support
   Systems (OSS).

   This document is built on RFC 5920 by providing additional security
   considerations which are applicable to the MPLS-TP extensions. The
   security models, threats, requirements, and defense techniques
   previously defined in [RFC5920] are assumed to apply to general
   aspect of MPLS-TP.

   This document is a product of a joint Internet Engineering Task Force
   (IETF) / International Telecommunication Union Telecommunication
   Standardization Sector (ITU-T) effort to include an MPLS Transport
   Profile within the IETF MPLS and PWE3 architectures to support the
   capabilities and functionality of a packet transport network.

   Readers can refer to [RFC5654] and [RFC5921] for MPLS-TP
   terminologies, and [RFC5920] for security terminologies which are
   relevant to MPLS and GMPLS.

1.1. Terminology

         Term     Definition
         ------   -----------------------------------------------
         AC       Attachment Circuit
         BFD      Bidirectional Forwarding Detection
         CE       Customer-Edge device
         DoS      Denial of Service
         G-ACh    Generic Associated Channel
         GAL      G-ACh Label
         GMPLS    Generalized Multi-Protocol Label Switching
         IP       Internet Protocol
         LDP      Label Distribution Protocol
         LSP      Label Switched Path
         NMS      Network Management System
         MPLS     MultiProtocol Label Switching
         MPLS-TP  MultiProtocol Label Switching Transport Profile



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         MS-PW    Multi-Segment Pseudowire
         OAM      Operations, Administration, and Maintenance
         PE       Provider-Edge device
         PSN      Packet-Switched Network
         PW       Pseudowire
         S-PE     PW Switching Provider Edge
         SP       Service Provider
         SS-PW    Single-Segment Pseudowire
         T-PE     PW Terminating Provider Edge

2. Security Reference Models

   This section defines reference models for security in MPLS-TP
   networks.

   The models are built on the architecture of MPLS-TP defined in
   [RFC5921]. The placement of Service Provider (SP) boundaries plays
   important role in determining the security models for any particular
   deployment.

   This document defines a trusted zone as being where a single SP has
   total operational control over that part of the network.  A primary
   concern is about security aspects that relate to breaches of security
   from the "outside" of a trusted zone to the "inside" of this zone.

2.1. Security Reference Model 1

   In reference model 1, a single SP has total control of the PE/T-PE to
   PE/T-PE part of the MPLS-TP network.

   Security reference model 1(a)

   An MPLS-TP network with Single Segment Pseudowire (SS-PW) from PE1 to
   PE2.  The trusted zone is PE1 to PE2 as illustrated in Figure 1.

















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          |<-------------- Emulated Service ---------------->|
          |                                                  |
          |          |<------- Pseudo Wire ------>|          |
          |          |                            |          |
          |          |    |<-- PSN Tunnel -->|    |          |
          |          v    v                  v    v          |
          v    AC    +----+                  +----+     AC   v
    +-----+    |     | PE1|==================| PE2|     |    +-----+
    |     |----------|............PW1.............|----------|     |
    | CE1 |    |     |    |                  |    |     |    | CE2 |
    |     |----------|............PW2.............|----------|     |
    +-----+  ^ |     |    |==================|    |     | ^  +-----+
          ^  |       +----+                  +----+     | |  ^
          |  |   Provider Edge 1         Provider Edge 2  |  |
          |  |                                            |  |
    Customer |                                            |Customer
    Edge 1   |                                            |Edge 2
             |                                            |
       Native service                               Native service

    ---Untrusted--- >|<------- Trusted Zone ----->|<---Untrusted----

                   Figure 1. MPLS-TP Security Model 1(a)

   Security reference model 1(b)

   An MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE1
   to T-PE2. The trusted zone is T-PE1 to T-PE2 in Figure 2.

        Native  |<-------------Pseudowire------------>|  Native
        Service |                                     |  Service
         (AC)   |     |<- PSN ->|     |<- PSN ->|     |   (AC)
           |    v     v         v     v         v     v     |
           |    +-----+         +-----+         +-----+     |
    +----+ |    |T-PE1|=========|S-PE1|=========|T-PE2|     | +----+
    |    |------|......PW.Seg't1.......PW.Seg't3......|-------|    |
    | CE1| |    |     |         |     |         |     |     | |CE2 |
    |    |------|......PW.Seg't2.......PW.Seg't4......|-------|    |
    +----+ |    |     |=========|     |=========|     |     | +----+
         ^      +-----+    ^    +-----+     ^   +-----+        ^
         |                 |                |                  |
         |               TP LSP            TP LSP              |
         |                                                     |
         |<----------------- Emulated Service ---------------->|

    -Untrusted->|<---------- Trusted Zone ----------->|<-Untrusted--

                   Figure 2. MPLS-TP Security Model 1(b)



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2.2. Security Reference Model 2

   In reference model 2, a single SP does not have the end-to-end
   control of the segment from PE/T-PE to PE/T-PE. Some S-PE(s), T-PE(s)
   may be under the control of other SPs, or the SP's customers, or its
   partners. In this case, the MPLS-TP network is not contained within a
   single trusted zone.

   Security Reference Model 2(a)

   An MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE1
   to T-PE2. The trusted zone is T-PE1 to S-PE1, as illustrated in
   Figure 3.

        Native  |<-------------Pseudowire------------>| Native
        Service |                                     | Service
         (AC)   |     |<--PSN-->|     |<--PSN-->|     |  (AC)
           |    V     V         V     V         V     V    |
           |    +-----+         +-----+         +-----+    |
    +----+ |    |T-PE1|=========|S-PE1|=========|T-PE2|    | +----+
    |    |------|......PW.Seg't1.......PW.Seg't3......|------|    |
    | CE1| |    |     |         |     |         |     |    | |CE2 |
    |    |------|......PW.Seg't2.......PW.Seg't4......|------|    |
    +----+ |    |     |=========|     |=========|     |    | +----+
         ^      +-----+    ^    +-----+     ^   +-----+      ^
         |                 |                |                |
         |               TP LSP            TP LSP            |
         |                                                   |
         |<---------------- Emulated Service --------------->|

    Untrusted-->|<-- Trusted Zone---->|<---------Untrusted--------

                  Figure 3. MPLS-TP Security Model 2(a)

   Security Reference Model 2(b)

   An MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from T-PE1
   to T-PE2. The trusted zone is the S-PE1 only, as illustrated in
   Figure 4.












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        Native  |<-------------Pseudowire------------>| Native
        Service |                                     | Service
         (AC)   |     |<--PSN-->|     |<--PSN-->|     |  (AC)
           |    V     V         V     V         V     V    |
           |    +-----+         +-----+         +-----+    |
    +----+ |    |T-PE1|=========|S-PE1|=========|T-PE2|    | +----+
    |    |------|......PW.Seg't1.......PW.Seg't3......|------|    |
    | CE1| |    |     |         |     |         |     |    | |CE2 |
    |    |------|......PW.Seg't2.......PW.Seg't4......|------|    |
    +----+ |    |     |=========|     |=========|     |    | +----+
         ^      +-----+    ^    +-----+     ^   +-----+      ^
         |                 |                |                |
         |               TP LSP            TP LSP            |
         |                                                   |
         |<---------------- Emulated Service --------------->|

    --------Untrusted---------->|<--->|<-------Untrusted----------
                                Trusted
                                 Zone

                  Figure 4. MPLS-TP Security Model 2(b)

   Security Reference Model 2(c)

   An MPLS-TP network with Multi-Segment Pseudowire (MS-PW) from
   different Service Providers with inter-provider PW connections. The
   trusted zone is T-PE1 to S-PE3, as illustrated in Figure 5.

     Native  |<--------------------- PW15 ------------------>| Native
      Layer  |                                               | Layer
    Service  |     |<PSN13>|     |<PSN3X>|     |<PSNXZ>|     | Service
      (AC1)  V     V  LSP  V     V  LSP  V     V  LSP  V     V (AC2)
          |  +-----+  +-+  +-----+       +-----+  +-+  +-----+ |
    +---+ |  |T-PE1|  | |  |S-PE3|       |S-PEX|  | |  |T-PEZ| | +---+
    |   | |  |     |=======|     |=======|     |=======|     | | |   |
    |CE1|----|........PW1........|..PW3..|........PW5........|---|CE2|
    |   | |  |     |=======|     |=======|     |=======|     | | |   |
    +---+    |  1  |  |2|  |  3  |       |  X  |  |Y|  |  Z  |   +---+
             +-----+  +-+  +-----+       +-----+  +-+  +-----+
             |<--Subnetwork 123->|       |<--Subnetwork XYZ->|

   Untrusted>|<-- Trusted Zone-->|<-------------Untrusted-------------

                  Figure 5. MPLS-TP Security Model 2(c)

   In general, the boundaries of a trusted zone must be carefully
   defined when analyzing the security properties of each individual
   network. The security boundaries determine which reference model



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   should be applied to given network topology.

3. Security Threats

   This section discusses various network security threats that are
   unique to MPLS-TP and may endanger MPLS-TP networks.

   Attacks to GAL or G-ACh may include:

      - GAL or BFD label manipulation, which includes insertion of false
      labels and modification, deletion, or replay of messages.

      - DoS attack through in-band OAM by generating excessive G-ACh/GAL
      and BFD messages which consume significant bandwidth and
      potentially cause congestion.

   These attacks can cause unauthorized protection switchover, inability
   to restore, or loss of network connectivity.

   When a NMS is used for LSP setup, the attacks to NMS can cause the
   above effect as well. Although this is not unique to MPLS-TP, MPLS-TP
   network can be particularly vulnerable to NMS attack due to the fact
   that static provisioning through NMS is a commonly used model. In the
   static provisioning model, a compromised NMS can potentially be
   comparable to a comprised control plane plus a comprised management
   plane in the dynamic controlled network model.

   Attacks to NMS may come from external attackers, or insiders. Outside
   attacks are initiated outside of the trusted zone by unauthorized
   user of the MPLS-TP network management systems. Insider attack is
   initiated from inside of the trusted zone by an entity with
   authorized access to the management systems, but performs unapproved
   harmful functions to the MPLS-TP networks. These attacks may be
   directly targeted to the NMS, or via the compromised communication
   channels between the NMS and the network devices that are being
   provisioned, or through the access of the users to the provisioning
   tools. The security threat may include disclosure of information,
   generating false OAM messages, taking down MPLS-TP LSPs, connecting
   to the wrong MPLS-TP tunnel end points, and DoS attacks to the MPLS-
   TP networks.

   There are other more generic security threat, such as: Unauthorized
   observation of data traffic (including traffic pattern analysis),
   modification, or deletion of a provider's or user's data, as well as
   replay or insertion of inauthentic data into a provider's or user's
   data stream. These types of attacks apply to MPLS-TP traffic
   regardless of how the LSP or PW is set up in a similar way to how
   they apply to MPLS traffic regardless how the LSP is set up. More



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   details on the above mentioned threat are documented in [RFC5920].

   The threats may be resulting from malicious behavior or accidental
   errors.

   Example 1: Attack from users: Users of the MPLS-TP network may attack
   the network infrastructure or attack other users.

   Example 2: Attack from insiders: Employees of the operators may
   attack the MPLS-TP network, especially through NMS.

   Example 3: Attack from inter-connecting SPs or other partners: Other
   SPs may attack the MPLS-TP network, particularly through the inter-
   provider connections.

   Example 4: Attack as the result of operation errors: Operation staff
   may fail to follow the operational procedures or make operational
   mistakes.

4. Defensive Techniques

   The defensive techniques presented in this document and in [RFC5920]
   are intended to describe methods by which some security threats can
   be addressed. They are not intended as requirements for all MPLS-TP
   deployments. The specific operational environment determines the
   security requirements for any instance of MPLS-TP. Therefore,
   protocol designers should provide a full set of security
   capabilities, which can be selected and used where appropriate.  The
   MPLS-TP provider should determine the applicability of these
   techniques to the provider's specific service offerings, and the end
   user may wish to assess the value of these techniques to the user's
   service requirements.

   Authentication is the primary defense technique to mitigate the risk
   of the  MPLS-TP security threat "GAL or BFD label manipulation", and
   "DoS attack through in-band OAM" discussed in Section 3.
   Authentication refers to methods to ensure that message sources are
   properly identified by the MPLS-TP devices with which they
   communicate. Authentication includes entity authentication for
   identity verification, management system authentication, peer-to-peer
   authentication, message integrity and replay detection to ensure the
   validity of message streams, network-based access controls such as
   packet filtering and firewalls, host-based access controls,
   isolation, aggregation, protection against denial of service, and
   event logging. Where these techniques apply to MPLS and GMPLS in
   general, they are described in Section 5.2 of [RFC5920].

   In addition to authentication, the following defense should also be



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   considered to protect MPLS-TP networks.

   - Use of Isolated Infrastructure for MPLS-TP

   One way to protect the MPLS-TP infrastructure network is to use
   dedicated network resources to provide MPLS-TP transport services.
   For example, in security model 2 (Section 2.2), the potential risk of
   attacks on the S-PE1 or T-PE1 in the trusted zone may be reduced by
   using non-IP-based communication paths, so that the paths in the
   trusted zone cannot be reached from the outside via IP.

   - Verification of Connectivity

   To protect against deliberate or accidental misconnection, mechanisms
   can be put in place to verify both end-to-end connectivity and
   segment-by-segment resources.  These mechanisms can trace the routes
   of LSPs in both the control plane and the data plane. Note that the
   connectivity verification tools are now developed for general MPLS
   networks as well.

   The defense techniques are apply generally to MPLS/GMPLS are not
   detailed here, for example:

      1) Authentication: including Management System Authentication,
      Peer-to-Peer Authentication, Cryptographic Techniques for
      Authenticating Identity;

      2) Access Control Techniques;

      3) Use of Aggregated Infrastructure;

      4) Mitigation of Denial of Service Attacks;

      5) Monitoring, Detection, and Reporting of Security Attacks.

   Readers can refer to [RFC5920] for details.

   It is important to point out the following security defense
   techniques which are particularly critical for NMS due to the strong
   emphasis on static provisioning supported by NMS in MPLS-TP
   deployment. These techniques include: Entity authentication for
   identity verification, encryption for confidentiality, message
   integrity and replay detection to ensure the validity of message
   streams, as well as users access control and events logging which
   must be applied for NMS and provisioning applications.

5. Security Considerations




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   Security considerations constitute the sole subject of this document
   and hence are discussed throughout.

   This document evaluates MPLS-TP specific security risks and
   mitigation mechanisms which may be used to counter the potential
   threats.  All of the techniques presented involve mature and widely
   implemented technologies that are practical to implement. It is meant
   to assist equipment vendors and service providers, who must
   ultimately decide what threats to protect against in any given
   configuration or service offering from a customer's perspective as
   well as from a service provider's perspective.

6. IANA Considerations

      This document contains no new IANA considerations.

7. Acknowledgements

   The authors wish to thank Joel Halpern and Gregory Mirsky for their
   review comments and contributions to this document, thank Mach Chen
   for his review and suggestions, thank Adrian Farrel for his Routing
   AD review and detailed comments, thank Loa Andersson for his
   continued support and guidance as the MPLS WG co-Chair, and thank Dan
   Romascanu and Barry Leiba for their helpful comments during IESG
   review.

8.  References

8.1.  Normative References

   [RFC5654]  Niven-Jenkins, B., Ed., Brungard, D., Ed., Betts, M., Ed.,
              Sprecher, N., and S. Ueno, "Requirements of an MPLS
              Transport Profile", RFC 5654, September 2009.

   [RFC5920]  Fang, L., Ed., "Security Framework for MPLS and GMPLS
              Networks", RFC 5920, July 2010.

8.2. Informative References

   [RFC5921]  Bocci, M., Ed., Bryant, S., Ed., Frost, D., Ed., Levrau,
              L., and L. Berger, "A Framework for MPLS in Transport
              Networks", RFC 5921, July 2010.









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Authors' Addresses

   Luyuan Fang (editor)
   Cisco Systems
   111 Wood Ave. South
   Iselin, NJ 08830, US
   Email: lufang@cisco.com

   Ben Niven-Jenkins (editor)
   Velocix
   326 Cambridge Science Park
   Milton Road
   Cambridge CB4 0WG, UK
   Email: ben@niven-jenkins.co.uk

   Scott Mansfield (editor)
   Ericsson
   300 Holger Way
   San Jose, CA 95134, US
   Email: scott.mansfield@ericsson.com

   Richard F. Graveman (editor)
   RFG Security, LLC
   15 Park Avenue
   Morristown, NJ 07960, US
   Email: rfg@acm.org

Contributors' Addresses

   Raymond Zhang
   Alcatel-Lucent
   750D Chai Chee Road
   Singapore 469004
   Email: raymond.zhang@alcatel-lucent.com

   Nabil Bitar
   Verizon
   40 Sylvan Road
   Waltham, MA  02145, US
   Email: nabil.bitar@verizon.com

   Masahiro Daikoku
   KDDI Corporation
   3-11-11 Iidabashi, Chiyodaku, Tokyo, Japan
   Email: ms-daikoku@kddi.com

   Lei Wang
   Lime Networks



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   Strandveien 30, 1366 Lysaker, Norway
   Email: lei.wang@limenetworks.no

   Henry Yu
   TW Telecom
   10475 Park Meadow Drive
   Littleton, CO 80124, US
   Email: henry.yu@twtelecom.com











































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