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Versions: (draft-venaas-mboned-mcaddrdoc) 00 01 02 03 04 RFC 6676

Network Working Group                                          S. Venaas
Internet-Draft                                                 R. Parekh
Intended status: Informational                           G. Van de Velde
Expires: November 18, 2012                                 cisco Systems
                                                                T. Chown
                                               University of Southampton
                                                              M. Eubanks
                                                 Iformata Communications
                                                            May 17, 2012


                 Multicast Addresses for Documentation
                   draft-ietf-mboned-mcaddrdoc-04.txt

Abstract

   This document discusses which multicast addresses should be used for
   documentation purposes and reserves multicast addresses for such use.
   Some multicast addresses are derived from AS numbers or unicast
   addresses.  This document also explains how these can be used for
   documentation purposes.

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 http://datatracker.ietf.org/drafts/current/.

   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 November 18, 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
   (http://trustee.ietf.org/license-info) in effect on the date of
   publication of this document.  Please review these documents



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   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
   2.  IPv4 multicast documentation addresses . . . . . . . . . . . .  4
     2.1.  Administratively scoped IPv4 multicast addresses . . . . .  4
     2.2.  GLOP multicast addresses . . . . . . . . . . . . . . . . .  4
     2.3.  Unicast prefix based IPv4 multicast addresses  . . . . . .  5
   3.  IPv6 multicast documentation addresses . . . . . . . . . . . .  6
     3.1.  Unicast prefix based IPv6 multicast addresses  . . . . . .  6
     3.2.  Embedded-RP IPv6 multicast addresses . . . . . . . . . . .  6
   4.  Security Considerations  . . . . . . . . . . . . . . . . . . .  8
   5.  IANA Considerations  . . . . . . . . . . . . . . . . . . . . .  9
   6.  Acknowledgments  . . . . . . . . . . . . . . . . . . . . . . . 10
   7.  Informative References . . . . . . . . . . . . . . . . . . . . 11
   Authors' Addresses . . . . . . . . . . . . . . . . . . . . . . . . 12





























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1.  Introduction

   It is often useful in documentation, IETF documents, etc., to provide
   examples containing IP multicast addresses.  For documentation where
   examples of general purpose multicast addresses are needed, one
   should use multicast addresses that never will be assigned or in
   actual use.  There is a risk that addresses used in examples may
   accidentally be used.  It is then important that the same addresses
   are not used by other multicast applications or services.  It may
   also be beneficial to filter out such addresses from multicast
   signalling and multicast data sent to such addresses.

   For unicast there are both IPv4 and IPv6 addresses reserved for this
   purpose, see [RFC5737] and [RFC3849] respectively.  This document
   reserves multicast addresses for this purpose.

   There are also some multicast addresses that are derived from AS
   numbers or unicast addresses.  For examples where such addresses are
   desired, one should derive them from the AS numbers and unicast
   addresses reserved for documentation purposes.  This document also
   discusses the use of these.






























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2.  IPv4 multicast documentation addresses

   For Any-Source Multicast (ASM), the IPv4 multicast addresses
   allocated for documentation purposes are 233.252.0.0 - 233.252.0.255
   (233.252.0.0/24).

   For Source-Specific Multicast (SSM) it is less important which
   multicast addresses are used, since a host/application joins a
   channel identified by both source and group.  Any source addresses
   used in SSM examples should be unicast addresses reserved for
   documentation purposes.  There are three unicast address ranges
   provided for documentation use in [RFC5737].  The ranges are
   192.0.2.0/24, 198.51.100.0/24 and 203.0.113.0/24.

   Sometimes one wants to give examples where a specific type of address
   is desired.  E.g. for text about multicast scoping, one might want
   the examples to use addresses that are to be used for administrative
   scoping.  See below for guidance on how to construct specific types
   of example addresses.

2.1.  Administratively scoped IPv4 multicast addresses

   Administratively scoped IPv4 multicast addresses [RFC2365] are
   reserved for scoped multicast.  They can be used within a site or an
   organization.  Apart from a small set of scope relative addresses,
   these addresses are not assigned.  The high order /24 in every scope
   is reserved for relative assignments.  A relative assignment is an
   integer offset from the highest address in the scope and represents
   an IPv4 address.  For documentation purposes, the integer offset is
   TBD1.  This provides one multicast address per scope.

   For example in the Local Scope 239.255.0.0/16, the multicast address
   for documentation purposes is 239.255.255.255-TBD1.

2.2.  GLOP multicast addresses

   GLOP [RFC3180] is a method for deriving IPv4 multicast group
   addresses from 16-bit AS numbers.  For examples where GLOP addresses
   are desired, the addresses should be derived from the AS numbers
   reserved for documentation use.

   The 16-bit AS numbers reserved for documentation use in [RFC5398] are
   64496 - 64511.  By use of [RFC3180], we then get 16 /24 multicast
   prefixes for documentation use.  The first one 233.251.240.0/24, and
   the last 233.251.255.0/24.






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2.3.  Unicast prefix based IPv4 multicast addresses

   IPv4 multicast addresses can be derived from IPv4 unicast prefixes,
   see [RFC6034].  For examples where this type of addresses are
   desired, the addresses should be derived from the unicast addresses
   reserved for documentation purposes, see [RFC5737].

   There are three unicast address ranges provided for documentation use
   in [RFC5737].  The ranges are 192.0.2.0/24, 198.51.100.0/24 and
   203.0.113.0/24.  Using [RFC6034] this leaves us with the unicast
   prefix based IPv4 multicast addresses 234.192.0.2, 234.198.51.100 and
   234.203.0.113.







































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3.  IPv6 multicast documentation addresses

   For Any-Source Multicast (ASM) the IPv6 multicast addresses allocated
   for documentation purposes are TBD2.  This is a /96 prefix so that it
   can be used with group IDs according to the allocation guidelines in
   [RFC3307]).  Also note that for these addresses the transient flag,
   the T-flag as defined in [RFC3513], is zero.  This is because they
   are permanently assigned.  There can be no permanently assigned
   addresses for documentation purposes with the transient flag set to
   one, since the flag set to one means that they are not permanently
   assigned.

   For Source-Specific Multicast (SSM) it is less important which
   multicast addresses are used, since a host/application joins a
   channel identified by both source and group.  Any source addresses
   used in SSM examples should be unicast addresses reserved for
   documentation purposes.  The IPv6 unicast prefix reserved for
   documentation purposes is 2001:DB8::/32, see [RFC3849].

   Sometimes one wants to give examples where a specific type of address
   is desired.  E.g. for text about multicast scoping, one might want
   the examples to use addresses that are to be used for administrative
   scoping.  See below for guidance on how to construct specific types
   of example addresses.

3.1.  Unicast prefix based IPv6 multicast addresses

   IPv6 multicast addresses can be derived from IPv6 unicast prefixes,
   see [RFC3306].  For examples where this type of addresses is desired,
   the addresses should be derived from the unicast addresses reserved
   for documentation purposes.

   The IPv6 unicast prefix reserved for documentation purposes is 2001:
   DB8::/32, see [RFC3849].  This allows a wide range of different IPv6
   multicast addresses.  Using just the base /32 prefix, one gets the
   IPv6 multicast prefixes FF3X:20:2001:DB8::/64, one for each available
   scope X. One can also produce longer prefixes from this.  Just as an
   example, one can pick say a /64 prefix 2001:DB8:DEAD:BEEF::/64 which
   gives the multicast prefixes FF3X:40:2001:DB8:DEAD:BEEF::/96, one for
   each available scope X.

3.2.  Embedded-RP IPv6 multicast addresses

   There is a type of IPv6 multicast addresses called Embedded-RP
   addresses where the IPv6 address of a Rendezvous-Point is embedded
   inside the multicast address, see [RFC3956].  For examples where this
   type of addresses is desired, the addresses should be derived from
   the unicast addresses reserved for documentation purposes, see



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   [RFC3849].

   For documentation purposes, the RP address can be any address from
   the range 2001:DB8::/32 that follows the constraints specified in
   [RFC3956].  One example address could be 2001:DB8::1.  The
   embedded-RP multicast prefixes might then be FF7X:120:2001:DB8::/96.
   Another example could be the RP address 2001:DB8:BEEF:FEED::7 which
   gives the prefixes FF7X:740:2001:DB8:BEEF:FEED::/96.  See also the
   examples in [RFC3956].










































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4.  Security Considerations

   The use of specific multicast addresses for documentation purposes
   has no negative impact on security.















































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5.  IANA Considerations

   IANA is requested to add a reference to this document for the IPv4
   MCAST-TEST-NET allocation, so that all the different documentation
   multicast assignments reference this document.

   IANA is requested to assign a scope relative IPv4 address for
   documentation purposes.

   This paragraph contains some further instructions for IANA in order
   to clarify.  It should be deleted before publishing.  The string TBD1
   in this document should be replaced by the assigned offset.  Also the
   string 255-TBD1 should be replaced by the value of 255 minus the
   assigned offset.  The next available offset seems currently to be 10.
   Look in the registry for where it says "10-252 Reserved - To be
   assigned by the IANA".  If the value 10 is chosen, then we would like
   to add "10 MCAST-TEST-NET-2 [RFCxxxx]" to the table.  TBD1 would then
   be 10.  TBD1 is used in two places apart from the IANA
   considerations.  In one place it says just TBD1, that should be
   replaced by "10".  The other place it says "239.255.255.255-TBD1".
   That should then be replaced by "239.255.255.245".  In the unlikely
   event that 10 is not available, please use the first available value
   accordingly.  MCAST-TEST-NET-2 is suggested here, since the existing
   allocation is named MCAST-TEST-NET.

   IANA is requested to assign "variable scope" IPv6 multicast addresses
   for documentation purposes.  This should be a /96 prefix.

   This paragraph contains some further instructions for IANA in order
   to clarify.  It should be deleted before publishing.  The word TBD2
   in this text should be replaced with the assigned prefix.  The prefix
   should be of the form FF0X:.../96.  In order to make this
   documentation prefix easily recognizable, the authors would like to
   request the prefix FF0X::DB8:0:0/96 if possible.  This makes it
   somewhat similar to the IPv6 unicast prefix 2001:DB8::/32.  We
   suggest they are denoted as "Documentation Addresses" with a
   reference to this document.














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6.  Acknowledgments

   The authors thank Roberta Maglione, Leonard Giuliano and Dave Thaler
   for providing comments on this document.















































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7.  Informative References

   [RFC2365]  Meyer, D., "Administratively Scoped IP Multicast", BCP 23,
              RFC 2365, July 1998.

   [RFC3180]  Meyer, D. and P. Lothberg, "GLOP Addressing in 233/8",
              BCP 53, RFC 3180, September 2001.

   [RFC3306]  Haberman, B. and D. Thaler, "Unicast-Prefix-based IPv6
              Multicast Addresses", RFC 3306, August 2002.

   [RFC3307]  Haberman, B., "Allocation Guidelines for IPv6 Multicast
              Addresses", RFC 3307, August 2002.

   [RFC3513]  Hinden, R. and S. Deering, "Internet Protocol Version 6
              (IPv6) Addressing Architecture", RFC 3513, April 2003.

   [RFC3849]  Huston, G., Lord, A., and P. Smith, "IPv6 Address Prefix
              Reserved for Documentation", RFC 3849, July 2004.

   [RFC3956]  Savola, P. and B. Haberman, "Embedding the Rendezvous
              Point (RP) Address in an IPv6 Multicast Address",
              RFC 3956, November 2004.

   [RFC5398]  Huston, G., "Autonomous System (AS) Number Reservation for
              Documentation Use", RFC 5398, December 2008.

   [RFC5737]  Arkko, J., Cotton, M., and L. Vegoda, "IPv4 Address Blocks
              Reserved for Documentation", RFC 5737, January 2010.

   [RFC6034]  Thaler, D., "Unicast-Prefix-Based IPv4 Multicast
              Addresses", RFC 6034, October 2010.



















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Authors' Addresses

   Stig Venaas
   cisco Systems
   Tasman Drive
   San Jose, CA  95134
   USA

   Email: stig@cisco.com


   Rishabh Parekh
   cisco Systems
   Tasman Drive
   San Jose, CA  95134
   USA

   Email: riparekh@cisco.com


   Gunter Van de Velde
   cisco Systems
   De Kleetlaan 6a
   Diegem  1831
   Belgium

   Phone: +32 476 476 022
   Email: gvandeve@cisco.com


   Tim Chown
   University of Southampton
   Highfield
   Southampton, Hampshire  SO17 1BJ
   United Kingdom

   Email: tjc@ecs.soton.ac.uk














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   Marshall Eubanks
   Iformata Communications
   130 W. Second Street
   Dayton, Ohio  45402
   US

   Phone: +1 703 501 4376
   Email: marshall.eubanks@iformata.com
   URI:   http://www.iformata.com/










































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