Survey Report on Protocol Independent Multicast - Sparse Mode (PIM-SM) Implementations and Deployments

Internet Engineering Task Force (IETF)                          L. Zheng
Request for Comments: 7063                           Huawei Technologies
Category: Informational                                         Z. Zhang
ISSN: 2070-1721                                         Juniper Networks
                                                               R. Parekh
                                                           Cisco Systems
                                                           December 2013


 Survey Report on Protocol Independent Multicast - Sparse Mode (PIM-SM)
                    Implementations and Deployments

Abstract

   This document provides supporting documentation to advance the IETF
   stream's Protocol Independent Multicast - Sparse Mode (PIM-SM)
   protocol from Proposed Standard to Internet Standard.

Status of This Memo

   This document is not an Internet Standards Track specification; it is
   published for informational purposes.

   This document is a product of the Internet Engineering Task Force
   (IETF).  It represents the consensus of the IETF community.  It has
   received public review and has been approved for publication by the
   Internet Engineering Steering Group (IESG).  Not all documents
   approved by the IESG are a candidate for any level of Internet
   Standard; see Section 2 of RFC 5741.

   Information about the current status of this document, any errata,
   and how to provide feedback on it may be obtained at
   http://www.rfc-editor.org/info/rfc7063.

Copyright Notice

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Table of Contents

   1. Motivation ......................................................3
      1.1. Overview of PIM-SM .........................................3
      1.2. Requirements of RFCs 2026 and 6410 .........................3
   2. Survey on Implementations and Deployments .......................4
      2.1. Methodology ................................................4
      2.2. Operator Responses .........................................4
           2.2.1. Description of PIM-SM Deployments ...................4
           2.2.2. PIM-SM Deployment with Other Multicast
                  Technologies ........................................4
           2.2.3. PIM-SM Rendezvous Points (RPs) and RP
                  Discovery Mechanisms ................................4
      2.3. Vendor Responses ...........................................5
           2.3.1. Implementations Based on RFCs 4601 and 2362 .........5
           2.3.2. Lack of (*,*,RP) and PMBR Implementations ...........5
           2.3.3. Implementations of Other Features of RFC 4601 .......5
      2.4. Key Findings ...............................................6
   3. Security Considerations .........................................6
   4. Acknowledgements ................................................6
   5. References ......................................................6
      5.1. Normative References .......................................6
      5.2. Informative References .....................................7
   Appendix A. Questionnaire ..........................................8
     A.1. PIM Survey for Operators ....................................8
     A.2. PIM Survey for Implementors ................................10

1.  Motivation

1.1.  Overview of PIM-SM

   Protocol Independent Multicast - Sparse Mode (PIM-SM) was first
   published as [RFC2117] in 1997.  This version was then obsoleted by
   [RFC2362] in 1998.  The protocol was classified as Experimental in
   both documents.  The protocol specification was then rewritten in
   whole and advanced to Proposed Standard as [RFC4601] in 2006.
   Considering its multiple independent implementations developed and
   sufficient successful operational experience gained, the PIM WG
   decided to advance the PIM-SM protocol to Internet Standard.  The
   conducted survey and this document are part of the work.

1.2.  Requirements of RFCs 2026 and 6410

   [RFC2026] defines the stages in the standardization process, the
   requirements for moving a document between stages, and the types of
   documents used during this process.  Section 4.1.2 of [RFC2026]
   states that:

      The requirement for at least two independent and interoperable
      implementations applies to all of the options and features of the
      specification.  In cases in which one or more options or features
      have not been demonstrated in at least two interoperable
      implementations, the specification may advance to the Draft
      Standard level only if those options or features are removed.

   [RFC6410] updates the IETF Standards Process defined in [RFC2026].
   Primarily, it reduces the Standards Process from three Standards
   Track maturity levels to two.  The second maturity level is a
   combination of Draft Standard and Standard as specified in [RFC2026].
   Section 2.2 of [RFC6410] states that:

      (1) There are at least two independent interoperating
      implementations with widespread deployment and successful
      operational experience.

      (2)...

      (3) There are no unused features in the specification that greatly
      increase implementation complexity.

   Optional features that do not meet the aforesaid criteria have been
   identified by the PIM Working Group and will be removed.  This
   document provides supporting documentation to advance the IETF
   stream's Protocol Independent Multicast - Sparse Mode (PIM-SM)
   protocol from Proposed Standard to Internet Standard.

2.  Survey on Implementations and Deployments

2.1.  Methodology

   A questionnaire was issued by the PIM WG co-chairs and announced
   widely to the vendors and operational community to obtain information
   on PIM-SM implementations and deployments.  The survey concluded on
   22 Oct 2012.  The responses remain confidential and only combined
   results are published here, while responders chose whether to keep
   their affiliations confidential.  The raw questionnaire is shown in
   Appendix A, and a compilation of the responses is included in the
   following section.

2.2.  Operator Responses

   Nine operators responded to the survey.  They are SWITCH, National
   Research Council Canada, South Dakota School of Mines and Technology,
   Motorola Solutions, and five anonymous operators.

2.2.1.  Description of PIM-SM Deployments

   Since 1998, PIM-SM has been deployed for a wide variety of
   applications: Campus, Enterprise, Research and WAN networks,
   Broadband ISP, and Digital TV.  There are five deployments based on
   [RFC4601] implementations and two on [RFC2362] implementations.  PIM-
   SM for IPv6 has been deployed by three operators.  Out of the nine
   operators, six have deployed PIM-SM implementations from multiple
   vendors.

   Operators reported minor interoperability issues and these were
   addressed by the vendors.  There was no major interoperability
   concern reported by the operators.

2.2.2.  PIM-SM Deployment with Other Multicast Technologies

   Except for one deployment of PIM-SM with Multicast Extensions to OSPF
   (MOSPF), all other operators have deployed PIM-SM exclusively.  No
   operators acknowledged deployments of either (*,*,RP) or PIM
   Multicast Border Route (PMBR) for interconnection between PIM-SM and
   other multicast domains.

2.2.3.   PIM-SM Rendezvous Points (RPs) and RP Discovery Mechanisms

   The number of PIM-SM RPs deployed by operators ranges from a few
   (e.g., sixteen) to a massively scaled number (four hundred).  Both
   static configuration and Bootstrap Router (BSR) have been deployed as
   RP discovery mechanisms.

   Anycast-RP has been deployed for RP redundancy.  Two operators have
   deployed Anycast-RP using the Multicast Source Discovery Protocol
   (MSDP) [RFC3446].  Three operators have deployed Anycast-RP using
   both MSDP [RFC3446] and PIM [RFC4610] for different scenarios.  The
   best common practice seems to be to use static-RP configuration with
   Anycast-RP for redundancy.

2.3.  Vendor Responses

   Eight vendors reported PIM-SM implementations.  They are XORP, Huawei
   Technologies, Cisco Systems, Motorola Solutions, Juniper Networks,
   and three other anonymous vendors.

2.3.1.  Implementations Based on RFCs 4601 and 2362

   Four vendors reported PIM-SM implementations based on [RFC4601] and
   two reported PIM-SM implementations based on [RFC2362].  Two other
   reported implementations are hybrids.

   Minor interoperability issues have been addressed by the vendors over
   the years and no concerns were reported by any vendor.

2.3.2.  Lack of (*,*,RP) and PMBR Implementations

   Most vendors have not implemented (*,*,RP) state as specified in
   [RFC4601] either due to lack of deployment requirements or due to
   security concerns.  Similarly, most vendors have also not implemented
   PMBR due to lack of deployment requirements or because it was
   considered too complex and non-scalable.

   Only one vendor, XORP, reported (*,*,RP) and PMBR implementation and
   they were implemented just because these were part of the [RFC4601]
   specification.

2.3.3.  Implementations of Other Features of RFC 4601

   Most vendors have implemented all of the following from the [RFC4601]
   specification:

   o  Source-Specific Multicast (SSM)

   o  Join suppression

   o  Explicit tracking

   o  Register mechanism

   o  Shortest Path Tree (SPT) switchover at last-hop router
   o  Assert mechanism

   o  Hashing of group to RP mappings

   Some vendors do not implement explicit tracking and SSM.

2.4.  Key Findings

   PIM-SM has been widely implemented and deployed for different
   applications.  The protocol is sufficiently well specified in
   [RFC4601] resulting in interoperable implementation deployed by
   operators.

   There are no deployments and only one known implementation of
   (*,*,RP) and PMBR as specified in [RFC4601].  Hence, it is necessary
   to remove these features from the specification as required by
   [RFC2026] and [RFC6410].

3.  Security Considerations

   The PIM WG is aware of at least three (and believes there are more)
   PIM-SM implementations that support the use of IPsec to protect PIM
   messages.  For at least one of them, IPsec is not part of the PIM
   implementation itself -- one just configures IPsec with Security
   Policy Databases (SPDs) where interface, the ALL_PIM_ROUTERS
   multicast address, etc., can be used as selectors, according to
   [RFC5796].

4.  Acknowledgements

   The authors would like to thank Tim Chown and Bill Atwood, who helped
   to collect and anonymize the responses as the neutral third party.
   Special thanks are also given to Alexander Gall, William F. Maton
   Sotomayor, Steve Bauer, Sonum Mathur, Pavlin Radoslavov, Shuxue Fan,
   Sameer Gulrajani, and to the anonymous responders.

5.  References

5.1.  Normative References

   [RFC2026]  Bradner, S., "The Internet Standards Process -- Revision
              3", BCP 9, RFC 2026, October 1996.

   [RFC6410]  Housley, R., Crocker, D., and E. Burger, "Reducing the
              Standards Track to Two Maturity Levels", BCP 9, RFC 6410,
              October 2011.

5.2.  Informative References

   [RFC2117]  Estrin, D., Farinacci, D., Helmy, A., Thaler, D., Deering,
              S., Handley, M., Jacobson, V., Liu, C., Sharma, P., and L.
              Wei, "Protocol Independent Multicast-Sparse Mode (PIM-SM):
              Protocol Specification", RFC 2117, June 1997.

   [RFC2362]  Estrin, D., Farinacci, D., Helmy, A., Thaler, D., Deering,
              S., Handley, M., and V. Jacobson, "Protocol Independent
              Multicast-Sparse Mode (PIM-SM): Protocol Specification",
              RFC 2362, June 1998.

   [RFC3446]  Kim, D., Meyer, D., Kilmer, H., and D. Farinacci, "Anycast
              Rendevous Point (RP) mechanism using Protocol Independent
              Multicast (PIM) and Multicast Source Discovery Protocol
              (MSDP)", RFC 3446, January 2003.

   [RFC4601]  Fenner, B., Handley, M., Holbrook, H., and I. Kouvelas,
              "Protocol Independent Multicast - Sparse Mode (PIM-SM):
              Protocol Specification (Revised)", RFC 4601, August 2006.

   [RFC4610]  Farinacci, D. and Y. Cai, "Anycast-RP Using Protocol
              Independent Multicast (PIM)", RFC 4610, August 2006.

   [RFC5796]  Atwood, W., Islam, S., and M. Siami, "Authentication and
              Confidentiality in Protocol Independent Multicast Sparse
              Mode (PIM-SM) Link-Local Messages", RFC 5796, March 2010.

Appendix A.  Questionnaire

   This section provides copies of the questionnaires exactly as
   distributed to operators and implementors.

A.1.  PIM Survey for Operators

   Introduction:

   PIM-SM was first published as RFC2117 in 1997 and then again as
   RFC2362 in 1998.  The protocol was classified as Experimental in
   both of these documents.  The PIM-SM protocol specification was then
   rewritten in whole and advanced to Proposed Standard as RFC4601 in
   2006.  Considering the multiple independent implementations developed
   and the successful operational experience gained, the IETF has
   decided to advance the PIM-SM routing protocol to Draft Standard.
   This survey intends to provide supporting documentation to advance
   the Protocol Independent Multicast - Sparse Mode (PIM-SM) routing
   protocol from IETF Proposed Standard to Draft Standard.  (Due to
   RFC6410, now the intention is to progress it to Internet Standard.
   Draft Standard is no longer used.)

   This survey is issued on behalf of the IETF PIM Working Group.

   The responses will be collected by a neutral third-party and kept
   strictly confidential if requested in the response; only the final
   combined results will be published.  Tim Chown and Bill Atwood have
   agreed to anonymize the response to this Questionnaire.  They have a
   long experience with multicast but have no direct financial interest
   in this matter, nor ties to any of the vendors involved.  Tim is
   working at University of Southampton, UK, and he has been active in
   the IETF for many years, including the mboned working group, and he
   is a co-chair of the 6renum working group.  Bill is at Concordia
   University, Montreal, Canada, and he has been an active participant
   in the IETF pim working group for over ten years, especially in the
   area of security.

   Please send questionnaire responses addressed to them both.  The
   addresses are tjc@ecs.soton.ac.uk and william.atwood@concordia.ca.
   Please include the string "RFC4601 bis Questionnaire" in the subject
   field.

   Before answering the questions, please complete the following
   background information.

   Name of the Respondent:

   Affiliation/Organization:

   Contact Email:

   Provide description of PIM deployment:

   Do you wish to keep the information provided confidential:

   Questions:

   1 Have you deployed PIM-SM in your network?

   2 How long have you had PIM-SM deployed in your network?  Do you know
     if your deployment is based on the most recent RFC4601?

   3 Have you deployed PIM-SM for IPv6 in your network?

   4 Are you using equipment with different (multi-vendor) PIM-SM
     implementations for your deployment?

   5 Have you encountered any inter-operability or backward-
     compatibility issues amongst differing implementations?  If yes,
     what are your concerns about these issues?

   6 Have you deployed both dense mode and sparse mode in your network?
     If yes, do you route between these modes using features such as
     *,*,RP or PMBR?

   7 To what extent have you deployed PIM functionality, like BSR, SSM,
     and Explicit Tracking?

   8 Which RP mapping mechanism do you use: Static, AutoRP, or BSR?

   9 How many RPs have you deployed in your network?

   10 If you use Anycast-RP, is it Anycast-RP using MSDP (RFC 3446) or
      Anycast-RP using PIM (RFC4610)?

   11 Do you have any other comments on PIM-SM deployment in your
      network?

A.2.  PIM Survey for Implementors

   Introduction:

   PIM-SM was first published as RFC2117 in 1997 and then again as
   RFC2362 in 1998.  The protocol was classified as Experimental in both
   of these documents.  The PIM-SM protocol specification was then
   rewritten in whole and advanced to Proposed Standard as RFC4601 in
   2006.  Considering the multiple independent implementations developed
   and the successful operational experience gained, the IETF has
   decided to advance the PIM-SM routing protocol to Draft Standard.
   This survey intends to provide supporting documentation to advance
   the Protocol Independent Multicast - Sparse Mode (PIM-SM) routing
   protocol from IETF Proposed Standard to Draft Standard.  (Due to
   RFC6410, now the intention is to progress it to Internet Standard.
   Draft Standard is no longer used.)

   This survey is issued on behalf of the IETF PIM Working Group.

   The responses will be collected by a neutral third-party and kept
   strictly confidential if requested in the response; only the final
   combined results will be published.  Tim Chown and Bill Atwood have
   agreed to anonymize the response to this Questionnaire.  They have a
   long experience with multicast but have no direct financial interest
   in this matter, nor ties to any of the vendors involved.  Tim is
   working at University of Southampton, UK, and he has been active in
   the IETF for many years, including the mboned working group, and he
   is a co-chair of the 6renum working group.  Bill is at Concordia
   University, Montreal, Canada, and he has been an active participant
   in the IETF pim working group for over ten years, especially in the
   area of security.

   Please send questionnaire responses addressed to them both.  The
   addresses are tjc@ecs.soton.ac.uk and william.atwood@concordia.ca.
   Please include the string "RFC 4601 bis Questionnaire" in the subject
   field.

   Before answering the questions, please complete the following
   background information.

   Name of the Respondent:

   Affiliation/Organization:

   Contact Email:

   Provide description of PIM implementation:

   Do you wish to keep the information provided confidential:

   Questions:

   1 Have you implemented PIM-SM?

   2 Is the PIM-SM implementation based on RFC2362 or RFC4601?

   3 Have you implemented (*,*, RP) state of RFC4601?  What is the
     rationale behind implementing or omitting (*,*,RP)?

   4 Have you implemented the PMBR as specified in RFC4601 and RFC2715?
     What is the rationale behind implementing or omitting PMBR?

   5 Have you implemented other features and functions of RFC4601:

   - SSM

   - Join Suppression

   - Explicit tracking

   - Register mechanism

   - SPT switchover at last-hop router

   - Assert mechanism

   - Hashing of group to RP mappings

   6 Does your PIM-SM implementation support IPv6?

   7 Have you encountered any inter-operability issues with other PIM
     implementations in trials or in the field?

   8 Do you have any other comments or concerns about PIM-SM as
     specified in RFC4601?

Authors' Addresses

   Lianshu Zheng
   Huawei Technologies
   China

   EMail: vero.zheng@huawei.com


   Zhaohui Zhang
   Juniper Networks
   USA

   EMail: zzhang@juniper.net


   Rishabh Parekh
   Cisco Systems
   USA

   EMail: riparekh@cisco.com