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

                                                             INFN/CNAF
                                                           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.

Overview

 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.

Abstract

 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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transparency to the final user: user applications should not be

influenced.

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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 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
 applications.

 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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Security Considerations

 Security issues are not discussed in this memo.

Authors' Addresses

 Davide Salomoni
 INFN-CNAF
 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
 INFN-CNAF
 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
 INFN-CNAF
 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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