Network Working Group H. Alvestrand
Request for Comments: 1802 UNINETT
Category: Informational K. Jordan
Control Data Systems
S. Langlois
Electricite de France
J. Romaguera
NetConsult
June 1995
Introducing Project Long Bud:
Internet Pilot Project for the Deployment of X.500 Directory
Information in Support of X.400 Routing
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.
Abstract
The Internet X.400 community (i.e., GO-MHS) currently lacks a
distributed mechanism providing dynamic updating and management of
message routing information. The IETF MHS-DS Working Group has
specified an approach for X.400 Message Handling Systems to perform
message routing using OSI Directory Services. The MHS-DS approach
has been successfully tested in a number of local environments.
This memo describes a proposed Internet Pilot Project that seeks to
prove the MHS-DS approach on a larger scale. The results of this
pilot will then be used to draw up recommendations for a global
deployment.
1. Background
The 1988 edition of X.400 introduces, among other extensions or
revisions, the concept of O/R Names which assumes the existence of a
widely available Directory Service. This Directory Service is needed
to support several MHS operations (support for names to identify
senders and receivers of messages in a user-friendly fashion, support
for distribution lists, authentication of MHS components, description
of MHS components capabilities...).
The prime advantage of Directory Names, as perceived by many users,
was to release users from the remembering of complex O/R Addresses
for their correspondents.
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In the MHS infrastructure, as compared to other protocols, a name by
itself does not contain enough information to allow the Message
Transfer Agents (MTAs) to route a message to the User Agent (UA)
servicing this name. The routing process is based on information
provided by different MHS Management Domains, whether they are public
or private.
An MHS community combines several administrative MHS domains among
which agreements for cooperative routing exist: the GO-MHS community
is the set of MTA's taking care of X.400 mail operations on the
Internet [RFC 1649].
In the absence of a distributed Directory Service, an interim
technique has been developed within the GO-MHS community to collect
and advertise routing information. This resulted in an experimental
IETF protocol [RFC 1465].
2. Rationale
A number of routing problems are preventing the present Internet
X.400 service from expanding its number of participating message
transfer agents to a global scale. The two most critical problems
are:
* The present mechanism of centrally maintained and advertized
MTA routing tables has been optimized as far as possible.
Increasing the number of directly connected MTAs increases also
the workload on the MHS managers. The current solution does
not scale. Routing must be a fully dynamic and distributed
process.
* Manual propagation and installation of routing tables do not
guarantee consistency of routing information (even in a loose
fashion) when it is accessed by different MTAs scattered across
the globe.
It is commonly accepted that a distributed mechanism providing for
dynamic updating and management of X.400 routing information is
highly desirable. The focus of the project is to establish X.500-
based support of X.400 routing, at a very large scale.
3. Benefits
Using the Directory as a dynamic means of information storage and
advertisement will guarantee participants in Project Long Bud that
their updated data are globally available to the community. As a
direct consequence of the above, a participating MHS manager will be
released from configuring connections to the other participants.
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Directory-capable MTAs will be able to discover more optimal and more
direct routes to X.400 destinations than are practical today. This
will enable faster delivery of messages.
The infrastructure reliability will be improved: the information
stored in the Directory will allow automatic use of backup
connections in case of remote MTA or network problems. X.400 mail
managers in the GO-MHS Community should then be released from the
need to know the complexity of the whole mail routing infrastructure.
Providing a dynamic routing infrastructure will eliminate
inconsistencies introduced by unsynchronized static tables and
improve quality of service.
Furthermore, besides the robustness and the optimization of the new
routing infrastructure, the Long Bud approach should bring to the
participating organizations better control over how they establish
and maintain their interconnection with the GO-MHS community.
Participants will share in building an X.400 network which can expand
to a very large scale. They will develop experience using a global
messaging architecture which scales well and requires minimal
administrative overhead. They will be able to discuss experience
with the MHS-DS experts and architects in the ongoing standards
development cycle.
4. Definition of project LONG BUD
The Long Bud pilot wishes to demonstrate that the X.500 Directory is
able to provide a global-scale service to messaging applications.
Although MHS-DS provides ways to use private routing trees, Long Bud
will focus on the Open Community Routing Tree as used by the GO-MHS
community.
4.1 Project Goals
Project Long Bud has the following goals:
* Gather pilot experience of the defined framework for X.500
support of MTA routing, as defined by the IETF MHS-DS Working
Group [Kille 94].
* Actively investigate migration of the existing operational
X.400 service from a routing method based upon distribution of
centrally maintained static tables, as specified in [RFC 1465],
to a method based instead upon X.500:
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-- Deploy X.400 MTAs which are directly capable of reading
routing information from the X.500 Directory, in
compliance with the specifications of the MHS-DS Working
Group. This type of MTA is called a directory-capable
MTA.
-- Deploy tools which read routing information from the X.500
Directory and use it to generate static routing tables for
MTAs which are not directory-capable.
* specify a set of minimal operational requirements needed before
X.500-based routing of X.400 messages can be widely deployed.
4.2 Phasing
The first phase of Project Long Bud consists in deploying a small
number of directory-capable MTAs operated by members of the MHS-DS
Working Group and GO-MHS community. These MTAs must be capable of
using information in the X.500 directory to route messages to all
other members of the project as well as to the existing GO-MHS
community. As of this writing, an initial set of MTAs is already
operational.
At the end of this phase, the following goals should be achieved:
* The X.500 DIT must be populated with enough routing information
to allow the participating MTAs to route reliably messages to
each other and to the existing GO-MHS community.
* The X.500 DSAs holding the routing information must operate at
a quality of service that is acceptable for an operational
X.400 service.
As a prerequisite, a sufficient number of MTA managers must be
willing to participate in Project Long Bud for the first set of
results to be significant. Support for a protocol stack conforming
to [RFC 1006] is mandatory. All MTAs participating in the Long Bud
pilot need to register in the Open Tree and must be prepared to
accept connections from anyone.
Note that in the first phase, default routes will be established in
the DIT such that messages addressed to destinations outside of the
Long Bud community will be routed to designated MTAs in the GO-MHS
community. This will allow for full connectivity between the Long
Bud community and the GO-MHS community which are related, but
distinct communities. Interworking between these two must be
established and coordinated.
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In the second phase of Project Long Bud, a greater number of MTAs
should be added to the experiment. Cooperation with non directory-
capable communities must be addressed.
4.3 General Approach
No large scale resources have been committed to this project. Yet,
expedient deployment is desirable. Therefore, the pilot project
needs to be focused and relatively short-lived. The general approach
for satisfying these requirements includes:
* Use as many existing MHS-DS tools as possible. Also, continue
to track the progress of tools being developed by project
members and facilitate their deployment as soon as they are
ready.
* Coordinate efforts with existing GO-MHS community service.
* Establish a core infrastructure: 4 DSAs (two in the United
States and two in Europe) are set up to serve MHS-DS
information.
* Wherever it is technically feasable, DSA managers will
establish bilateral agreements with one (or more) of the core
DSAs in order to duplicate their routing information. For
example, the core DSAs support the replication protocol
specified in [RFC 1275] as a duplication technique.
* the Long Bud pilot needs to cooperate actively with DANTE
NameFlow (the continuation of the PARADISE Pilot) and other
directory providers in order to promote stability and
consistency of informations.
4.4 Tools Needed
To facilitate widespread deployment of MHS-DS routing technology and
to foster interworking between directory-capable MTAs and MTAs which
are not directory-capable, tools providing the following
functionalities need to be developed:
populate the Directory with routing information: such a tool must
accept routing information specified in the standard syntax
used by the GO-MHS community (see [RFC 1465]) as input, and it
will load or update entries which convey the same information
in the X.500 Directory.
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downloading of routing information from the Directory: in order to
provide a migration path for organizations not using
directory-capable MTAs, a tool is needed which will read X.400
routing information from the X.500 Directory and generate
static routing information from it. The syntax of the static
information generated will conform to the syntax defined by the
GO-MHS community, so that "classical" MTAs run as they
currently do.
displaying route taken by a message between two end-points: this
tool should accept two parameters as input: the X.500
distinguished name of an MTA, and an X.400 O/R name. It will
display the possible routes which may be taken in order to
deliver a message from the specified MTA to the specified X.400
destination. This tool looks very much the same as the
traceroute facility used at the IP level.
These tools must use standard protocols to access the Directory (such
as DAP [CCITT 88] or LDAP [RFC 1487]). Portability is encouraged.
A note on quality
Pilot use of this Directory information depends heavily on data
quality and availability. Although the administration of DSA
availability and global Directory data accuracy are not in the scope
of Long Bud, care must be taken that Directory resources used by Long
Bud participants are administrated well.
If they have the technical ability to do so, Long Bud participants
are encouraged to replicate routing information in their Directory to
improve data availability.
Directory data used by the pilot must be accurate: solutions to this
problem will be recommanded as the project matures.
5. Participation Guide
The existing operational X.400 service, the GO-MHS service, uses the
following method to distribute and manage X.400 routing information:
A group of MTAs is organized into a routing community. The community
keeps its routing information up to date by assigning to each MTA
manager the responsibility of determining the routing information for
his/her MTA, formalizing this routing information in the syntax
defined by the community and sending the result to the GO-MHS
coordination service. Once the information has been validated
against the other data provided by all managers in the community, the
coordination service will advertise it to the whole community. Each
manager will then have to update his/her MTA configuration with the
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verified information.
The purpose of Project Long Bud is to allow a manager to operate an
MTA without having to perform ANY manual steps when another MTA
manager adds new or changes existing routing information. This will
facilitate efficient, dynamic, and manageable interconnection of very
large communities of MTAs. It will allow the Internet X.400
community to overcome the limitations in scalability which it is
currently encountering.
5.1 Prerequisites for participation
The prerequisites for joining Project Long Bud are:
Step 1: Participants in the pilot must have a good knowledge of
the IETF MHS-DS Working Group activities and documents:
1. Participants must join the MHS-DS distribution list:
RFC-822: mhs-ds@mercury.udev.cdc.com
X.400: PN=mhs-ds; OU=mercury; OU=OSS;
OU=ARH; O=CPG; P=CDC; A=ATTMail; C=US
Requests to join the MHS-DS distribution list may be sent
to the following email address:
RFC-822: mhs-ds-request@mercury.udev.cdc.com
X.400: PN=mhs-ds-request; OU=mercury; OU=OSS;
OU=ARH; O=CPG; P=CDC; A=ATTMail; C=US
2. Participants must retrieve and become familiar with all
relevant tools and documents stored on the Project Long
Bud anonymous FTP server
Host name: ftp.css.cdc.com
Directory: pub/mhs-ds/long-bud
In particular, openly available software related to Long
Bud activities will be kept up-to-date at this location.
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3. If not already done, participants must do one of the
following:
* Upgrade their X.400 and X.500 software such that it
supports the MHS-DS specifications as in [Kille 94].
* Use the tools which extract MHS-DS information from
the directory and generate whatever local
configuration files are necessary to allow local MTA's
to use the information. This should be done
frequently (at least once per day).
Step 2: Participants must register required entries in the
Directory so that their MTA(s) is (are) known to the
Directory.
1. Arrange with the appropriate DSA Manager (who can be a
local manager if the DSA is run by the participating
organization, or a manager who is in charge of running the
organization's DSA) to create an entry for the local
MTA(s) involved in the pilot. At this stage, only
connection information is required.
2. Check, test and verify the connection information with at
least one other participant. The mhs-ds distribution list
should be used for announcing the new registration and
asking volunteers for testing.
3. Participants must establish sensible default X.400 routes
to existing GO-MHS destinations for which X.500-based
routing information will not exist initially.
Step 3: Participants can then enter their routing information in
the Directory.
1. Before any routing is entered in the DIT, participants
must check with the GO-MHS Coordination Service that the
routes they want to register can be properly handled by
the GO-MHS community (contact information is
mailflow@mailflow.dante.net). It is crucial for the Pilot
that any routing information entered in the Directory is
kept carefully accurate if the experiment is to be
meaningful. Participants may also consider the need for
mapping rules (see [RFC 1465] for details).
2. Once the above step is validated by the GO-MHS
Coordination Service, participants must record routing
information for their MTA(s) in the Internet X.500
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directory service. This requires that a participant does
the following:
* Arrange with the appropriate DSA Manager (who can be
either a local manager if the DSA is run by the
participating organization or a manager which is in
charge of running the organization's DSA) to enter
X.400 routing information in a routing tree held by
the participating organization. This routing tree
should contain all necessary information for the local
mail domain.
* Check, test and verify the registered routing
information with at least one other participant. The
mhs-ds distribution list should be used for announcing
the new registration and asking volunteers for
testing.
3. If a participant adds new nonleaf entries to the Open
Community Routing Tree, then s/he must find at least one
other participant who will maintain a slave copy of the
children of the nonleaf entry. Send email to the mhs-ds
distribution list in order to find a partner who is
willing to do this.
4. If a participant adds new nonleaf ADMD or PRMD entries to
the directory, then s/he must contact the managers of the
Long Bud core DSA's and arrange to provide slave copies of
the children of the ADMD and/or PRMD entries to all of the
core DSA's. Send email to the mhs-ds distribution list in
order to contact the core DSA managers.
5. Once the above testing is completed, send email to the
mhs-ds distribution list announcing the establishment of
new X.500-based routes.
6. Notes on side effects
The Long Bud Pilot Project, with its specific scope, is investigating
a new direction in X.500 service usage. This should facilitate and
expedite the global deployment of X.500 on the Internet.
Once the routing infrastructure illustrated by the Long Bud
experiment is in place, the routing process will be able to take into
account additional information to improve quality of service
(minimizing messages conversions, enforcing various security policies
established by MHS domains, taking advantage of recipients's
capabilities stored in the Directory, ...). While the Open Tree
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provides global connectivity, multiple private routing trees allow
the use of various routing trees.
7. Acknowledgements
The authors would like to thank Urs Eppenberger (SWITCH) and Allan
Cargille (University of Wisconsin) for their constructive comments on
earlier drafts of this document.
References
[CCITT 88] International Telegraph and Telephone
Consultative Committee. X.500 Recommendations
series. December 1988.
[RFC 1649] Hagens, R., and A. Hansen, "Operational
Requirements for X.400 Management Domains in the
GO-MHS Community", RFC 1649, ANS, UNINETT,
July 1994.
[Kille 94] Kille, S., "MHS Use of the X.500 Directory to
Support MHS Routing", RFC 1801, ISODE Consortium,
June 1995.
[RFC 1006] Rose, M., and D. Cass, "ISO Transport Service on
top of the TCP Version: 3", STD 35, RFC 1006,
Northrop Research and Technology Center,
May 1987.
[RFC 1275] Hardcastle-Kille, S., "Replication Requirements
to provide an Internet Directory using X.500",
RFC 1275, University College London,
November 1991.
[RFC 1465] Eppenberger, U., "Routing Coordination for X.400
MHS Services Within a Multi Protocol / Multi
Network Environment Table Format V3 for Static
Routing", RFC 1465, SWITCH, May 1993.
[RFC 1487] Yeong, W., Howes, T., and S. Kille, "X.500
Lightweight Directory Access Protocol",
RFC 1487, Performance Systems International,
University of Michigan, ISODE Consortium,
July 1993.
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8. Security Considerations
Security issues are not discussed in this memo.
Authors' Addresses
Harald T. Alvestrand
UNINETT
P.O. box 6883 Elgeseter
N-7002 Trondheim, Norway
Phone: +47-73-59-70-94
EMail: Harald.T.Alvestrand@uninett.no
Kevin E. Jordan
Control Data Systems, Inc.
4201 Lexington Avenue North
Arden Hills, MN 55126, USA
Phone: +1-612-482-6835
EMail: Kevin.E.Jordan@cdc.com
Sylvain Langlois
Electricite de France
Direction des Etudes et Recherches
1, avenue du General de Gaulle
92141 Clamart Cedex, France
Phone: +33-1-47-65-44-02
EMail: Sylvain.Langlois@der.edf.fr
James A. Romaguera
NetConsult AG
Morgenstrasse 129 3018 Bern, Switzerland
Phone: +41-31-9984141
EMail: Romaguera@NetConsult.ch
X.400: S=Romaguera;O=NetConsult;P=switch;A=arcom;C=ch
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