RFC1676: INFN Requirements for an IPng

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Network Working Group                                        A. Ghiselli
Request for Comments: 1676                                   D. Salomoni
Category: Informational                                       C. Vistoli
                                                             August 1994

                     INFN Requirements for an IPng

Status of this Memo

   This memo provides information for the Internet community.  This memo
   does not specify an Internet standard of any kind.  Distribution of
   this memo is unlimited.


   This document was submitted to the IETF IPng area in response to RFC
   1550.  Publication of this document does not imply acceptance by the
   IPng area of any ideas expressed within.  Comments should be
   submitted to the big-internet@munnari.oz.au mailing list.


   This white paper is sent by INFN network team, the Italian National
   Institute for nuclear physics, whose network, named INFNet, is a
   nationwide network founded to provide the access to existing national
   and international HEP laboratory and to facilitate communications
   between the researchers.  With this paper we would like to emphasize
   the key points that we would to consider if charged with IPng plan.
   We do not really expect to add original items to the selection, but
   we think that it could be useful to submit the opinions and ideas
   that come from our network experience.

1. General Requirements

   The problems that are to be solved in IP internet are mainly three:

      1. address exhaustion

      2. flat address space

      3. routing efficiency, flexibility and capacity.

   The aim of IPng study should be to define a plan that solves all
   these problems as a whole and not each of them separately.

   The general requirements that we underline for this transition are:

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RFC 1676             INFN Requirements for an IPng           August 1994

      - transparency to the final user: user applications should not be

      - flexibility: Simplify the suitability to new communication
        technology and to topology changes due to new services provided
        or to different users needs.

2. Application and Transport Level

   Starting from the top of the OSI model, we think that the users
   applications should not be influenced by the migration plan.  It
   means that the TCP (the transport layer) must maintain the same
   interfaces and services to the upper layers.  Anyway, it is also
   necessary to foresee the use of a different transport services. The
   possibility to use different transport should be offered to the
   applications.  Therefore a transport selector field is needed.

3. Network layer: service and address

   We assume that the network layer must continue to provide the same
   datagram service as IP does.  CLNS could be a solution and a reliable
   starting point for the IPng.  The main advantage is that this
   solution has been profitable tested and it is already available on
   many systems.  It is not, of course, deployed as widely as IPv4 is,
   since it is a newer technology, but it is widely configured and and
   there is already operational experience.  The corresponding address,
   the NSAP, is 20 bytes long.  It is long enough to scale the future
   data network environment.  Its hierarchical format can be organized
   in a really flexible way, satisfying hierarchical routing and policy
   based routing needs and simplifying the distributed administration
   and management.  A lot of work has been already done in the majority
   of the countries in order to define NSAP formats satisfying both the
   requirements of administrative delegation and routing performances.

4. Routing protocols

   We don't consider the decision about the routing protocol to be
   adopted for the IPng to be fundamental.  Even if this choice is very
   important to obtain good performances, the routing protocols can be
   changed or improved at any time, because there is no influence into
   the End Systems configuration.  Relationships between NSAP
   aggregation, hierarchical topology and hierarchical routing algorithm
   must be taken into account in IPng plan.  These issues could improve
   administration and topological flexibility of the IPng and solve the
   flat problem of the IPv4.  The IPng routing protocols should include
   policy-based features.  The IPv4 network topology is very complex and
   it will continue to enlarge during the transition. It would be very
   difficult or impossible to manage it without the "policy" tools.  The

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RFC 1676             INFN Requirements for an IPng           August 1994

   multicast capability as well as any other new features that fit in a
   datagram network should be supported.  Regarding the Source Routing
   feature, since we think that it deeply modifies the aim and the
   "philosophy" of a connectionless network and it also introduces an
   heavy complication in the end nodes and routers software, we don't
   consider it a major issue.

5. Layer 2 or communication infrastructure media support.

   This is an open field, rapidly changing, then it must be left open to
   any evolution. What it should be recommended is to be compatible with
   the above network layer.

6. Transition and Deployment

   We faced the problem of the transition of the DECNET global network
   to DECNET/OSI over CLNS. This activity is now proceeding to the last
   step and based on this experience we would underline some points that
   we found important during the transition deployment.  The transitions
   must be planned and developed in a distributed way.  This means that
   every organization should have the possibility to plan and start
   their network migration without loosing connectivity with the
   existing global internet.  Of course, the compatibility with the IPv4
   world must be maintained, this mean that a new generation system must
   interwork with both the IPv4 and IPng nodes, using the same

   However, it is important to define a deadline for the backward
   compatibility in order to avoid huge software maintenance in the user
   systems and a "multi-topology" management.  We think that a dual
   stack approach could simplify very much the transition, whereas a
   translation mechanism would need a widely and deep coordination in
   order to maintain the global connectivity during the transition
   period.  The dual stack is simpler and could be easily developed, but
   it is important to push in order to have pure IPng with global
   connectivity as soon as possible; this could happen when there are no
   more "IPv4 only" hosts.

   Indeed, the drawback of the dual stack configuration is that you
   continue to suffer for the IPv4 address space exhaustion and that you
   must continue to support the IPv4 routing protocols and
   infrastructure.  We don't think that the tunnel solution to
   interconnect the IPv4 isle could give good performances to the users.
   Then, it is important to maintain the IPv4 connectivity and the dual
   stack software support in the End System software in a determined
   timeframe, or the transition will never end.

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RFC 1676             INFN Requirements for an IPng           August 1994

Security Considerations

   Security issues are not discussed in this memo.

Authors' Addresses

   Davide Salomoni
   National Institute of Nuclear Physics - National Networking Center
   V.le Ercolani, 8
   40138 Bologna - Italy

   Phone:  +39 51 6098-260
   Fax:    +39 51 6098 135
   EMail: Salomoni@infn.it

   Cristina Vistoli
   National Institute of Nuclear Physics - National Networking Center
   V.le Ercolani, 8
   40138 Bologna - Italy

   Phone:  +39 51 6098-260
   Fax:    +39 51 6098 135
   EMail: Vistoli@infn.it

   Antonia Ghiselli
   National Institute of Nuclear Physics - National Networking Center
   V.le Ercolani, 8
   40138 Bologna - Italy

   Phone:  +39 51 6098-267
   Fax:    +39 51 6098 135
   EMail: Ghiselli@infn.it

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