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

INTERNET-DRAFT                                              L. Fang, Ed.
Intended Status: Informational                                     Cisco
Expires: June 17, 2013                             B. Niven-Jenkins, Ed.
                                                                 Velocix
                                                       S. Mansfield, Ed.
                                                                Ericsson
                                                        R. Graveman, Ed.
                                                            RFG Security

                                                       December 17, 2012


                      MPLS-TP Security Framework
                draft-ietf-mpls-tp-security-framework-06

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 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) 2012 IETF Trust and the persons identified as the
   document authors. All rights reserved.

   This document is subject to BCP 78 and the IETF Trust's Legal
   Provisions Relating to IETF Documents
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document. Please review these documents
   carefully, as they describe your rights and restrictions with respect
   to this document. Code Components extracted from this document must
   include Simplified BSD License text as described in Section 4.e of
   the Trust Legal Provisions and are provided without warranty as
   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  . . . . . . . . . . . . . . . . . . . . .  8
   5. Security Considerations . . . . . . . . . . . . . . . . . . . .  9
   6. IANA Considerations . . . . . . . . . . . . . . . . . . . . . . 10
   7. Acknowledgements  . . . . . . . . . . . . . . . . . . . . . . . 10
   8.  References . . . . . . . . . . . . . . . . . . . . . . . . . . 10
     8.1.  Normative References . . . . . . . . . . . . . . . . . . . 10
     8.2. Informative References  . . . . . . . . . . . . . . . . . . 10
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 10
   Contributors' Addresses  . . . . . . . . . . . . . . . . . . . . . 11







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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 functionalities 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.

1.1. Terminology

      Term     Definition
      ------   -----------------------------------------------
      AC       Attachment Circuit
      BFD      Bidirectional Forwarding Detection
      CE       Customer-Edge device
      DoS      Denial of Service
      DDoS     Distributed Denial of Service
      G-ACh    Generic Associated Channel
      GAL      G-ACh Label
      GMPLS    Generalized Multi-Protocol Label Switching
      LDP      Label Distribution Protocol
      LSP      Label Switched Path
      MEP      Maintenance End Point
      MIP      Maintenance Intermediate Point
      MPLS     MultiProtocol Label Switching
      OAM      Operations, Administration, and Management
      PE       Provider-Edge device
      PSN      Packet-Switched Network
      PW       Pseudowire



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      S-PE     Switching 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 PE to PE.  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-PE to
   T-PE. 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     |
             |    +----+         +----+         +----+     |
      +----+ |    |TPE1|=========|SPE1|=========|TPE2|     | +----+
      |    |------|.....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 total control of the
   PE/T-PE to PE/T-PE part of the MPLS-TP network. S-PE and T-PE may be
   under the control of different SPs, or their customers or may not be
   trusted for some other reason.  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-PE to
   T-PE. The trusted zone is T-PE1 to S-PE, as illustrated in Figure 3.

          Native  |<------------Pseudowire---------->| Native
          Service |                                  | Service
           (AC)   |    |<--PSN-->|    |<--PSN-->|    |  (AC)
             |    V    V         V    V         V    V    |
             |    +----+         +----+         +----+    |
      +----+ |    |TPE1|=========|SPE1|=========|TPE2|    | +----+
      |    |------|.....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-PE to
   T-PE. The trusted zone is the S-PE, as illustrated in Figure 4.














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          Native  |<------------Pseudowire---------->| Native
          Service |                                  | Service
           (AC)   |    |<--PSN-->|    |<--PSN-->|    |  (AC)
             |    V    V         V    V         V    V    |
             |    +----+         +----+         +----+    |
      +----+ |    |TPE1|=========|SPE1|=========|TPE2|    | +----+
      |    |------|.....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)
             +----+   +-+   +----+         +----+   +-+   +----+
    +---+    |TPE1|   | |   |SPE3|         |SPEX|   | |   |TPEZ|   +---+
    |   |    |    |=========|    |=========|    |=========|    |   |   |
    |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 discuss various network security threats which are to
   MPLS-TP and may endanger MPLS-TP networks.

   A successful attack on a particular MPLS-TP network or on a SP's
   MPLS-TP infrastructure may cause one or more adverse effects.

   Attacks to GAL or G-ACh may include:

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

      - DoS attack through in-band OAM G-ACh/GAL and BFD messages.

   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, but
   MPLS-TP network can be particularly venerable as static provisioning
   through NMS is a commonly used model.

   Observation (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.

   The threats may be resulting from malicious behavior or accidental
   errors. For example: Users of the MPLS-TP network may attack the
   network or other users; employees of the MPLS-TP operators,
   especially people who operate the NMS, attackers who obtain physical
   access to a MPLS-TP SP's site; Other SPs in the case of MPLS-TP
   inter-provider connection.

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



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   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.

   The techniques discussed here include entity authentication for
   identity verification, encryption for confidentiality, 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]. The remainder of this section covers
   aspects that apply particularly to MPLS-TP.

   - Use of Isolated Infrastructure for MPLS-TP

   Thisis one way to protect the infrastructure used for support of
   MPLS-TP to separate the resources for support of MPLS-TP services
   from the resources used for other purposes. For example, in security
   model 2 (Section 2.2), the potential risk of attacks on the S-PE or
   T-PE in the trusted zone may be reduced by using non-IP-based
   communication paths.

   - 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 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) Use of Aggregated
   Infrastructure; 5) Mitigation of Denial of Service Attacks; 6)
   Monitoring, Detection, and Reporting of Security Attacks. Please
   refer to [RFC5920] for details.

5. Security Considerations

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

   This document evaluates MPLS-TP specific security risks and



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   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 Adrian
   Farrel for his Routing AD review and detailed comments, and thank Loa
   Andersson for his continued support and guidance as the MPLS WG co-
   Chair.

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.


Authors' Addresses

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

   Ben Niven-Jenkins (editor)



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   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
   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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