Network Working Group                                     U. Eppenberger
Request for Comments: 1465                                        SWITCH
                                                                May 1993


              Routing Coordination for X.400 MHS Services
          Within a Multi Protocol / Multi Network Environment
                   Table Format V3 for Static Routing

Status of this Memo

   This memo defines an Experimental Protocol for the Internet
   community.  Discussion and suggestions for improvement are requested.
   Please refer to the current edition of the "IAB Official Protocol
   Standards" for the standardization state and status of this protocol.
   Distribution of this memo is unlimited.

1. Introduction

   The usage of the X.400 Message Handling System (MHS) is growing
   rapidly, especially in the commercial world but much interest can
   also be found in the academic and research community.  New networks
   and new addresses come into use each and every day.  The underlying
   technology for different X.400 networks can vary depending on the
   transport network and the X.400 MHS implementations used.  As a large
   number of X.400 implementations now support multiple stacks, this
   offers the chance of implementing a world wide message handling
   service using the same electronic mail standard and, therefore,
   without the need of gateways with service reduction and without the
   restriction to a single common transport network.  This, however,
   leads to several problems for the MHS manager, two of which are:

   - Where do I route new X.400 addresses and

   - How do I connect to a MHS domain that uses an underlying
     technology that I do not support.

   This document proposes short term solutions to these problems.  It
   proposes a strategy for maintaining and distributing routing
   information and shows how messages can travel over different networks
   by using multi stack MTAs as relays.  Document formats and
   coordination procedures bridge the gap until an X.500 directory
   service is ready to store the needed connectivity and routing
   information.  The format has been designed to allow the information
   to be stored in an X.500 directory service while managers without
   directory service access may still use a table based approach.

   The routing structure proposed can be applied to a global MHS service



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RFC 1465        Routing Coordination for X.400 Services         May 1993


   but may also be used at a national level or even within an
   organisation.

   Many experts from IETF X.400-Operations Group and RARE Working Group
   1 on Message Handling Systems have read drafts of this document and
   contributed ideas and solutions.  I would especially like to thank
   Harald Alvestrand, Erik Huizer, Marko Kaittola, Allan Cargille and
   Paul-Andre Pays.

   This is the third version of a table format.  The first one was in
   use within COSINE-MHS for about two years.  A second version with
   major enhancements was then proposed which has been in use for the
   past year.  The third version will probably be the last one before it
   will be possible to switch to dynamic, directory service based
   routing.

2. Terminology

   MHS community

      One or more MHS domains form an MHS community.  Mail exchange
      between these MHS domains is defined by the coordination
      procedures within this document.  Examples of such communities are
      the Global Open MHS service GO-MHS and the COSINE-MHS service.

   MHS domain

      One or more MHS subtrees form an MHS domain.  This is a purely
      administrative grouping of MHS subtrees.  It is helpful, if
      someone is responsible for several MHS subtrees, to refer to an
      MHS domain instead of listing all the subtrees.

   MHS subtree

      An MHS subtree consists of the total of the mailboxes addressable
      within a subtree of the X.400 OR address space.

        Example:  O=SWITCH; P=SWITCH; A=ARCOM; C=CH;

        MHS domain of SWITCH in Switzerland, consisting of all
        mailboxes with O=SWITCH; P=SWITCH; A=ARCOM; C=CH; in the OR
        address.

   RELAY-MTA

      An X.400 MTA serving one or several MHS domains.  Note that the
      term WEP -Well Known Entry Point- has been used since the early
      X.400ies (1987/88) until now, giving the wrong impression of a



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      single entry point (and therefore a single point of failure).
      This document proposes to use the term RELAY-MTA, reflecting more
      clearly the functionality of the MTA.

   COSINE-MHS

      The COSINE-MHS community is mainly formed by European X.400
      service providers from the academic and research area, each of
      which is a member of RARE.  The COSINE-MHS community is used in
      the annex as an example for the usage of this document in a
      multinational environment.

3. Requirements

   X.400 MTAs can communicate using different transport and network
   protocol stacks.  For this document the stacks used in a WAN
   environment need to be considered:

                           Stack 1    Stack 2    Stack 3    Stack 4

      Transport Layer 4    TP0        TP4        RFC1006    TP0
      Networkservice 1-3   X.25       CLNS       TCP/IP     CONS

   A common protocol stack is not the only requirement to enable
   communication between two MTAs.  The networks to which the MTAs
   belong need to be interconnected.  Some well known networks are
   listed together with the stacks they use.

      Network                                Stack   Abbreviation

      Public Switched Packet Data Networks     1     Public-X.25
      International X.25 Infrastructure EMPB   1,4   EMPB-X.25
      US and European connectionless pilot     2     Int-CLNS
      Internet                                 2,3   Internet

   Note that several stacks may be supported over a single network.
   However communication between MTAs is only possible if the MTAs share
   at least a common stack AND a common network.

   Unlike SMTP/TCP/IP systems, there is no directory service available
   which would allow an MTA to look up the next MTA to which it should
   submit a message.  Routing within X.400 will continue to be table
   based until a solution using X.500 directory services is available.

   Furthermore it is not generally allowed to connect to any MTA even on
   the same network without being registered on the destination MTA.
   These restrictions require a large coordination effort and carefully
   configured and updated systems.



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4. Outline of the proposal

   This proposal offers a solution for describing information about
   X.400 message routing within an MHS community in RELAY-MTA and DOMAIN
   documents.  Basic information on the MHS community is documented in
   the corresponding COMMUNITY document.  All contact persons and
   RELAY-MTA administrators can be found in PERSON documents.  A future
   X.500 based solution may need extended information to overcome still
   unsolved problems like optimal routing or traffic optimization for
   messages with multiple recipients.  The information collected for the
   intermediate solution however is very basic.  All established
   coordination procedures will help and even speed up the future
   introduction of an X.500 based solution.

4.1 The COMMUNITY document

   For each MHS community there exists one single COMMUNITY document
   containing basic information.  First the contact information for the
   central coordination point can be found together with the addresses
   for the file server where all the documents are stored.  It also
   lists network names and stacks to be used in the RELAY-MTA and DOMAIN
   documents.  An MHS community must agree on its own set of mandatory
   and optional networks and stacks.

4.2 The RELAY-MTA document

   Every MHS domain in the community may designate one or more MTAs as
   RELAY-MTAs.  These RELAY-MTAs accept incoming connections from the
   RELAY-MTAs of the other MHS domains and in return are allowed to send
   messages to these RELAY-MTAs.  A RELAY-MTA is documented with all the
   necessary connection information in the corresponding RELAY-MTA
   document.

4.3 The DOMAIN document

   An MHS domain has a responsible person who sets up the routing
   entries for the domain in the DOMAIN document.  The primary RELAY-
   MTAs listed in the DOMAIN document as serving this MHS domain must,
   TOGETHER, offer at least connectivity to all networks and stacks
   listed as mandatory in the COMMUNITY document.  Optional RELAY-MTAs
   may be added, generally with higher priority, to allow more precise
   routing.

   An MHS domain may also decide not to operate a RELAY-MTA.  It will
   then only need agreements with one or more RELAY-MTAs from other MHS
   services which will relay for this domain.  The domain itself,
   however, must either create its own DOMAIN document or document its
   MHS subtrees jointly with another MHS domain.



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   The structure of the DOMAIN document is very straightforward.  It
   starts off with one or more MHS subtrees, each on its own line.
   After the domains follows a line indicating the responsible person
   for the MHS subtrees mentioned.  Finally the responsible RELAY-MTA(s)
   are listed with appropriate priorities.

4.4 The PERSON document

   All administrators and responsible persons are documented in PERSON
   documents.  The RELAY-MTA and DOMAIN documents contain just keys
   pointing to a PERSON document.  If such a person can already be found
   in an X.500 directory service, then the key consists of a
   Distinguished Name, else the key is just its OR address.

4.5 Coordination

   This approach requires an identified coordination point.  It is up to
   the MHS community to decide on the level of coordination and support
   to be provided and on the funding mechanisms for such activities.
   Basic information can be found in the COMMUNITY document.  The
   following list of support activities is considered mandatory for an
   operational service:

    - New RELAY-MTAs joining the service are tested and support is
      given to create the RELAY-MTA document.

    - New MHS domains joining the MHS community get assistance to set
      up RELAY-MTA(s) and/or find appropriate RELAY-MTA(s) and to
      create DOMAIN documents.

    - Updated documents are announced to the RELAY-MTA managers and
      responsible persons for the DOMAIN documents unless automatic
      distribution is used.

    - All the RELAY-MTA, DOMAIN and PERSON documents are made
      available on a file server together with the COMMUNITY document.
      The file server must at least be reachable via email.  MHS
      communities with a big number of documents may consider
      additional access methods like ftp and FTAM.

    - Tools should be made available to manage routing tables for the
      X.400 software used on the RELAY-MTAs or to fill in and check
      the documents.  The format of the documents has specifically
      been chosen to enable the use of automated tools.

   The RELAY-MTA managers must be aware that a large number of RELAY-
   MTAs in an MHS community may require significant operational
   resources to keep the local routing tables up-to-date and to



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   constantly monitor the correct functioning of the connections.  On
   the other hand more than one RELAY-MTA with a good connectivity to an
   MHS domain improves the overall robustness of the domain and thus the
   QOS.

   MHS communities may decide on additional mandatory requirements for
   the operation of a RELAY-MTA.  These may include a hot line, echo
   services, exchange of statistics, response time to problem reports,
   uptime of the RELAY-MTA, etc.  This will ensure a certain quality of
   service for the end users.

4.6 Routing

   The proposal addresses MHS communities spanning several
   organisations.  But it may also be used to manage routing within a
   single organisation or even a global MHS community.

   Two kinds of mail relays are defined, the primary RELAY-MTAs and the
   secondary RELAY-MTAs.  A primary or secondary RELAY-MTA must allow
   incoming connections from all other primary and secondary RELAY-MTAs
   with a common stack.  Primary RELAY-MTAs must be able to connect to
   all other primary RELAY-MTAs which share a common stack.  A secondary
   RELAY-MTA must connect to at least one primary RELAY-MTA.

   Each MHS community must define update procedures for the routing
   based on the documentation.  Automated update has to be studied
   carefully.

   An MHS community should also define procedures for new RELAY-MTAs and
   MHS domains joining the service.  Since the usage of X.400 is growing
   rapidly a flexible but well coordinated way of integrating new
   members into an MHS community is needed.  The proposed documentation
   format supports this by allowing primary and secondary RELAY-MTAs.
   All RELAY-MTAs accept incoming connections from each other.  Sending
   messages can be done by using the primary RELAY-MTAs only.  This
   allows new RELAY-MTAs to join the community as secondary and to get
   primary status when traffic flow increases.  Secondary RELAY-MTAs may
   also require a longer testing period.

5. The documents

   The definition is given in BNF-like syntax.  The following
   conventions are used:


    |    means choice

    \    is used for continuation of a definition over several lines



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    []   means optional

    {}   means repeated one or more times

    ()   is used to group choices

    \"   is used for double quotes in a text string

     is a Carriage Return and means that the next section starts
         on its own line.

   The definition is complete only to a certain level of detail.  Below
   this level, all expressions are to be replaced with text strings.
   Expressions without more detailed definition are marked with single
   quotes '.  The format and semantics should be clear from the names of
   the expressions and the comments given.

   Wherever the BNF definition requires a single blank, multiple blanks
   may be used to increase the readability.  Please note that for some
   field values the number of spaces is significant.

   Lines exceeding 80 characters should be wrapped at any convenient
   blank except at blanks which are significant.  The line is continued
   with at least one leading blank.

   Comments may be placed anywhere in the document but only on separate
   lines and without splitting wrapped lines.  Such a comment line must
   either start with a '#' sign followed by white space and the comment
   or consist of a single '#' on a single line.

   The documents must follow the case of the strings defined in BNF.
   Note that some values, especially connection parameters like TSEL or
   MTA password are case dependant too.

   The BNF definitions are ordered top-down.  See Appendix B for an
   alphabetically sorted list.

   A set of one COMMUNITY document and several RELAY-MTA, DOMAIN and
   PERSON documents belong together.  The detailed definitions can be
   found in the following chapters.

       ::= \
                             \
                            {  } \
                            {  } \
                            {  }




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5.1 Common Definitions

       ::= 'Distinguished Name'
                The string representation of a Distinguished Name is
                defined in the RFCxxxx.  If a Distinguished Name is
                used as a key in the documents, then the information
                can be fetched from the directory instead of checking
                the appropriate document.  But as long as not all
                managers in the same community have directory access,
                the same information must also be present in a
                document.  Note that Distinguished Names in the context
                of the routing documents are just used as key strings
                to point to other documents.

       ::= "Community: " \
                            ('community name' | ) 
                The 'community name' is a string identifying the MHS
                community to be used in the first line of all
                documents.

       ::= (([ "P=" 'PRMDname' "; " ] \
                            ["A=" 'ADMDname' "; " ] \
                            "C="  "; " \
                            "MTAname=" 'MTAname')
                            |  )
                A unique key is needed to identify the RELAY-MTA.  In
                addition to the MTA name itself, it is proposed to use
                OR address attributes of the management domain where
                the RELAY-MTA resides.  ADMD and PRMD fields are both
                optional and may be used to guarantee uniqueness of the
                key.  The values used are irrelevant.  Even non-
                printable characters like @ or ! are acceptable.  The
                result is not an address but a key string.  A
                Distinguished Name may be used instead.

       ::= ( |  )
                A unique key is necessary to make the links from the
                documents where a responsible person or an
                administrator is needed, to the PERSON documents.  It
                is either the OR address of the person or a
                Distinguished Name (if the person is already registered
                in the directory).

       ::= 'Two Character Country Code ISO-3166'

       ::= 'OR address, ISO 10021-2 Annex F'
                It has been used consequently all over the document.
                This explains also the syntax of the



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                 and the . Examples:
                S=user; O=org ltd.; OU1=sect1; P=org; A=rel400; C=aq;
                DDA:RFC-822=we(a)sell.it; P=internet; A= ; C=xx;
                G=john; I=w; S=doe; P=org; A=rel400; C=aq;

       ::= "Address: "  

       ::=  [{"; " }]

       ::=  {"+"  " "  \
                            [" x" ]}
                This syntax follows the attribute syntax of the X.500
                directory based on CCITT E.123.

       ::= 'international prefix'

       ::= 'national telephone number'
                A national number may be written with spaces and
                hyphens to group the figures.

       ::= 'local extension'

       ::= "Phone: "  
                One or more phone numbers

       ::= "Fax: "  
                One or more FAX numbers

       ::= "Mail: " 'postal address information' 
                The items of the postal address are separated by ' /'
                wherever the next item goes onto the next line for a
                printed address label.  If the document is for an
                international community, the address should include the
                person's country.
                Example:
                Mail: SWITCH Head Office / Urs Eppenberger /
                      Limmatquai 138 / CH-8001 Zurich / Switzerland
                results in the following mailing label:
                SWITCH Head Office
                Urs Eppenberger
                Limmatquai 138
                CH-8001 Zurich
                Switzerland

       ::= "Update: FORMAT=V3; DATE=" 'yymmdd' \
                            "; START=" 'yymmdd' \
                            ["; END=" 'yymmdd'] 
                The  contains also the format identifier.



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                The date of the last update of a document is given in
                the form 'yymmdd'.
                A start date must be set.  A document can be published
                this way before the information in it is valid.  (This
                is especially useful in absence of automated tools.
                RELAY-MTA managers get more time to prepare their
                systems.)
                An end date is used to set an expiration date for the
                document.

       ::= 'String encoded Presentation Address'
                The format of this string follows RFC1278, A string
                encoding of Presentation Address and RFC1277, Encoding
                Network Addresses to support operation over non-OSI
                layers.  See chapter 5.2 about the usage of macros in a
                Presentation Address.

       ::=  "/" \
                             "/" \
                            
                The service type consists of a string with three parts
                concatenated with a "/": Network-name/Network-
                service/Transport-Protocol.

       ::= 'Name of a network'
                The network-name string identifies a network.  A well
                known key word should be chosen.  (No '/' character is
                allowed.)
                Examples: Public-X.25, Internet, EMPB-X.25, Int-CLNS,
                WIN, Janet,

       ::= 'Name of a network service'
                Examples: X.25, CONS, CLNS, TCP

       ::= 'Name of a transport protocol'
                Examples: TP0, TP2, TP4, RFC1006

                Since network and stack information forms one string,
                it identifies in an easy way a connection possibility
                between two RELAY-MTAs.  The COMMUNITY document defines
                the strings to be used in the RELAY-MTA and DOMAIN
                documents.  Some examples:
                Internet/TCP/RFC1006
                Public-X.25/X.25/TP0
                RARE-IXI/CONS/TP0
                RARE-CLNS/CLNS/TP4
                (It is probably important to mention here that this
                string has nothing to do with the format of a



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                presentation address as defined by Steve Hardcastle-
                Kille in RFC1278.  The problem of networks using the
                same address structure (X.121 DTEs, 4 Byte Internet
                addresses) but not being connected is not addressed in
                RFC1278 but solved by using the proposed service
                identifier above in addition to the presentation
                address.  As long as there are network islands, there
                is no other way than the addition of an 'island'-
                identifier.

       ::= ["O=" 'Organization-name' "; "] \
                            ["OU1="'OrganizationalUnit'"; "\
                            ["OU2=" 'OrganizationalUnit' "; " \
                            ["OU3=" 'OrganizationalUnit' "; " \
                            ["OU4=" 'OrganizationalUnit' "; "]]]] \
                            ["P=" 'PRMDname' "; "] \
                            "A=" 'ADMDname' "; " \
                            "C="  ";"

       ::= "Reachable: "  { "-"  "; "} \
                             

       ::= 'hh:mm'

       ::= ("UTC+" | "UTC-") 'hhmm'
                The operation information is needed to know the time
                someone is reachable.  This information is important
                for communities spanning several time zones.
                'hhmm' is a four digit value, the first two digits
                indicate hours, the second two digits indicate minutes.
                Use "UTC+" for time zones east of Greenwich.  A simple
                formula helps to calculate the current time at the
                remote place:
                local-time - local-displacement + remote-displacement =
                remote-time
                18:00 - (UTC + 0100) + (UTC - 0800) = 09:00
                The  entry may be followed by a comment line
                indicating when Daylight Saving Time is in effect.
                This is especially reasonable for MHS communities
                spanning continents on the northern and southern
                hemisphere.

5.2 The COMMUNITY document

       ::=  \
                             \
                            
                The first line of the COMMUNITY document specifies the



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                 to be used in the header of all
                other documents belonging to the same community.  It is
                recommended to add a few comment lines to describe the
                members of this MHS community.

       ::=  \
                            [{}] \
                            {}

       ::=    \
                              
                Set of contact information for the coordination point

       ::=  [{}] \
                            [{}]
                All documents must be available at least to the
                managers of the MHS domains and the RELAY-MTAs through
                an email server.  If FTAM and FTP are also  available,
                the generation of automated update tools is much
                easier.
                It is suggested to have a single server.  If there is
                only one, knowing a single X.400 OR address will allow
                you to reach the server.  However for FTP and FTAM more
                system addresses may be possible depending on the
                number of available network connections (or service
                types as they are called in this document).

       ::= "Mail-server: " 
                The email address of the file server.

       ::= "FTP-server: " 'domain name' "; " \
                            'account-name' ["; " 'password'] 
                In addition to the domain name of the server, an
                account name and a password is given.  In most cases
                this will probably be something like "anonymous" and
                "guest".
                Some servers request the RFC822 address of the user.
                This is documented by using the string 'user@domain' as
                password entry.  The meaning is not to use
                'user@domain' literally as password while accessing the
                server (even if this would generally work too since the
                software often just checks the presence of an @ sign,)
                but to use ones own RFC822 email address.

       ::= "FTAM-server: "  "; "\
                            'account-name' ["; " 'password'] \
                            ["; X.500 " ] 
                The account name is often case sensitive.  Some FTAM



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                servers offer anonymous access with the account-name
                ANON.  Documenting an FTAM server with a Distinguished
                Name is only allowed if the server is registered in the
                directory.

       ::= "Macro: " 'Macro name' " " \
                            'Macro value' 
                Presentation addresses without the usage of macros are
                generally unreadable.  RFC1278 suggests a few macros.
                All macros which are allowed in a community must be
                defined in the COMMUNITY document.  It is recommended
                to use the proposed macros in RFC1278 and add new ones
                if necessary:
                Macro: Int-X25(80)        TELEX+00728722+X.25(80)+01+
                Macro: Janet-X25(80)      TELEX+00728722+X.25(80)+02+
                Macro: Internet-RFC-1006  TELEX+00728722+RFC-1006+03+

       ::= {} \
                            {[]}
                Note that at least one mandatory service type is
                needed.

       ::= "Mandatory-Service: " \
                             

       ::= "Optional-Service: " \
                             

5.3 The RELAY-MTA document

       ::=  \
                             \
                             \
                            
                A RELAY-MTA document contains the full description of a
                single RELAY-MTA.  Only one community is allowed.
                Since some of the information is community dependent,
                it would not be easily possible to have a single
                RELAY-MTA document used in different communities.

       ::= \
                            "RELAY-MTA: "  

       ::=   \
                            

       ::= "Status: " ("primary" | "secondary") 
                This defines if the RELAY-MTA has 'primary' or



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                'secondary' status.  See section 4.3 and 6 for more
                information.

       ::=   \
                            {}\
                            [] \
                            [] \
                            []
                More than one set of connection information may be
                present for RELAY-MTAs supporting several networks and
                protocol stacks.

       ::= "Password: " \
                            ("secret" | "none" | \
                            "value=\"" 'password' "\"") 
                If the keyword none is present, then no password is
                sent with the MTAname when this MTA initiates an RTS
                connection or responds to an incoming connection.
                Password: none

                If the keyword secret is present, then the connection
                needs a password which is not made publicly available.
                (For example, a community might keep a list of the
                passwords at the central coordination point.  The list
                would then be faxed to the RELAY-MTA managers.)
                Password: secret

                A password must be documented using the
                value="password" notation.  The double quotes around
                the password are needed, consider the case of a single
                blank as a password.
                Password: value=" "
                Password: value="nume-n-ine"

       ::=  \
                            [ ]

       ::= "RTS-dialog-mode: " \
                            ("TWA" | "MONOLOGUE") 

       ::= "RTS-checkpoint-size: " \
                            'checkpoint size' 

       ::= "RTS-window-size: " \
                            'window size' 

       ::= "Called-address: " \
                             "; " \



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                             "; "  \
                            ["; " ] 

       ::= "MTS-T" | "MTS-TP" | "MTS-TP-84"
                MTS-T:     mts-transfer
                MTS-TP:    mts-transfer-protocol
                MTS-TP-84: mts-transfer-protocol-1984
                See ISO 10021-6, Section 3, chapter 11.1 for more
                details on this matter.  X.400(84) systems only support
                mts-transfer-protocol-1984.

       ::= 'Integer 0..99'
                The lowest Integer corresponds to the highest priority
                as in DNS.  It is possible to set different priorities
                for each service type.  This may be chosen, for
                example, to distribute the load amongst different
                networks according to their available bandwidth.

       ::= "Calling-address: " \
                             "; " \
                             
                Since called and calling network addresses may differ
                in certain configurations and some X.400 systems do
                validation on calling network addresses, it is
                important to have this information in the RELAY-MTA
                document.  (Note: a calling X.121 address might change
                if the X.25 switch is reconfigured.  This will stop a
                RELAY-MTA from connecting to other RELAY-MTAs using
                address validation without having changed anything at
                the higher layers!)

       ::= "System: HW=" 'computer type' "; " \
                            "OS=" 'operating system' "; " \
                            "SW=" 'MHS  software' 
                It is optional to provide HW/SW information.
                Experience, however, has shown that a number of
                communication problems were more easily identified and
                solved with this information present and up-to-date.

       ::= "LocalDomain: "  
                This is a useful but optional extension to the
                documentation.
                The  is local to the RELAY-MTA.  The  attributes might be used together with
                S=nosuchuser; to do connectivity and availability
                tests.





Eppenberger                                                    [Page 15]

RFC 1465        Routing Coordination for X.400 Services         May 1993


       ::= "EchoServer: "  
                Some of the RELAY-MTAs might offer an echo server
                functionality.  It does make sense to document this in
                the RELAY-MTA document for test purpose.  This field is
                optional.

       ::= {"Administrator: "  }
                The contact details for the RELAY-MTA administrator can
                be found in the appropriate PERSON document.  It is
                possible to document a whole team using a distribution
                list if this is desired.  It is generally better to
                document one or more 'real' persons.

5.4 The DOMAIN document

       ::=  \
                             \
                            

      ::= {}  \
                            {}

       ::= "Domain: "   
                Note that it is not allowed to have equal  lines in different DOMAIN documents belonging to
                the same MHS community.  A Domain-entry line can only
                appear in one DOMAIN document.

       ::=  ( "* " | "= " )
                This qualifier defines how the following OR address
                attributes should be handled for the routing algorithm.
                If a '*' is present, a destination address of a message
                is matched by the "Domain:" entry if at least the OR
                address attributes in the "Domain:" entry are equal to
                the destination address.
                If a "=" is present, a destination address of a message
                is matched by the "Domain:" entry if there are exactly
                the same OR attributes in the destination address as in
                the "Domain:" entry.  (This restriction works for OU4,
                OU3, OU2, OU1, O, P, A and C only.)
                Example:
                a) Domain: * P=switch; A=arcom; C=ch;
                b) Domain: = P=switch; A=arcom; C=ch;
                The address S=eppenberger; P=switch; A=arcom; C=ch;
                matches both cases, a) and b).
                The address S=eppenberger; O=unibe; P=switch; A=arcom;
                C=ch; matches only case a).




Eppenberger                                                    [Page 16]

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       ::= {"Administrator: "  }
                This is the person responsible for the listed domains.
                His task is to get the agreement of the relaying
                RELAY-MTAs and keep the DOMAIN document up-to-date.
                This person is the only one authorized to make changes
                to this document.  Note that multiple administrators
                may be listed.

       ::=         "Relay: " \
                            ( 'UniqueRELAY-MTAkey' | \
                            "Internet-SMTP" ) "; " \
                             
                The priority is used to define the sequence in which
                different RELAY-MTAs may be tried in case of failure.
                A lower integer corresponds to a higher priority as in
                DNS.  Priorities 0..49 are used to indicate backup
                RELAY-MTAs.  Priorities 50..99 are used for RELAY-MTAs
                not acting as backup but as relay service provider for
                a network service type not supported by the main
                RELAY-MTA.
                The keyword "Internet-SMTP" is a placeholder for an
                RFC1327 gateway connected to Internet. The RELAY-MTA
                manager selects a gateway of his choice.

       ::= 

5.5 The PERSON document

       ::=  \
                             \
                             \
                            

       ::= "Key: "  

      ::=  {} {} \
                               

        ::= "Name: " 'name of person' 
                The name of the person is given.  The issue of the
                character set problem is not addressed in this
                document.  Especially international communities should
                restrict themselves to IA5 or ASCII.

       ::= "RFC822: "  
                This is the RFC-822 address of the person.  It is often
                a big help to know the RFC822 address of someone, for
                example if the X.400 system is not reachable.  This is



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                also the reason why it is possible to provide multiple
                OR and RFC822 addresses.  The first one is considered
                the primary one.

6. Routing rules

   All the users within the MHS community have the right to send
   messages to each other.  The general agreement is that the RELAY-MTA
   infrastructure is used according to the following routing rules.
   More direct connections based on bilateral agreements are fully
   accepted.

   A primary or secondary RELAY-MTA must allow incoming connections from
   all other primary and secondary RELAY-MTAs with a common stack.
   Primary RELAY-MTAs must be able to connect to all other primary
   RELAY-MTAs which share a common stack.  A secondary RELAY-MTA must
   connect to at least one primary RELAY-MTA.

   A message arriving at a RELAY-MTA must either be sent to the next
   RELAY-MTA based on the DOMAIN documents of the MHS community or it is
   sent to an MTA closer to the destination based on local routing
   decisions.  The following algorithm must be used when forwarding a
   message to the next RELAY-MTA:

      1) Select the relevant DOMAIN document by searching for a match of
      the Recipient address in the message with the entries in the
      document.

      If your own RELAY-MTA appears in this list, this indicates one of
      the following:

      - You offered relay services for another RELAY-MTA with higher
        priority.  Continue with step 2 to decide on the next RELAY-MTA.

      - Your RELAY-MTA is the final destination according the DOMAIN
        document of your community.  You need to forward the message to
        the final destination according local routing information.

      2) From the list of RELAY-MTAs select those that have at least one
      common network service type with your own RELAY-MTA.

      3) Now delete all secondary RELAY-MTAs from the list where no
      direct connection is desired.  For remaining RELAY-MTAs in the
      list no difference is made anymore between primary and secondary
      status.

      4) Select from this reduced set of RELAY-MTAs the one with the
      highest RELAY-MTA-priority.  If there is more than one RELAY-MTA



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      having the same priority, then select a RELAY-MTA of your choice.
      If your own RELAY-MTA appears in that list, then you are not
      allowed to send to a RELAY-MTA with lower or equal priority.

      5) If there are no service-priorities set in the corresponding
      RELAY-MTA document indicating which service type to use, you are
      free to choose the service type for connecting to the RELAY-MTA.
      However, if there are specific priorities set then select the
      service type with the highest priority.

      6) If the connection fails then try other service types in the
      sequence of descending priority.

      7) If no connection works for the selected RELAY-MTA, then check
      in the list for the one with the same priority, if possible, or
      else select one with the next lower priority.  If there is another
      RELAY-MTA with a RELAY-MTA-priority between 0..49, then select it
      and proceed at step 5.  Without another RELAY-MTA to try the
      currently selected RELAY-MTA will be retried.

6.1 How to use RELAY-MTA-priorities

   An example helps to explain the usage of RELAY-MTA-priorities.
   Internet/TCP/RFC1006 and Public-X.25/X.25/TP0 are mandatory service
   types in the community REMOTEmail.  The MHS domain P=REMOTE; A=ARCOM;
   C=CH; operates MTA-B, only connected to public X.25.  A second
   RELAY-MTA which is connected to both, Internet and public X.25 is
   needed to offer relay services.  A connection using Internet is
   considered cheap in this example.  Both service types are available
   at MTA-A.  Since MTA-B is the only RELAY-MTA responsible for relaying
   messages to P=REMOTE; A=ARCOM; C=CH; to the final destination it must
   have the highest priority.

      Community: REMOTEmail
      Domain: * P=REMOTE; A=ARCOM; C=CH;
      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-B; 20
      RELAY-MTA:  P=MTA-C; A=ARCOM; C=CH;MTAname=MTA-C; 80

                                       __________________________
      +-------+    X.25     +-------+ (                          )
      | MTA-A +-------------+ MTA-B +-( P=REMOTE; A=ARCOM; C=CH; )
      +-------+             +-------+ (__________________________)
               \           /
         TCP/IP \         /X.25
                 +-------+
                 | MTA-C |
                 +-------+




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   If MTA-A needs to relay a message for P=REMOTE; A=ARCOM; C=CH; then
   the rules of chapter 6 are evaluated:

        1. MTA-B and MTA-C are possible destinations

        2. MTA-B and MTA-C are reachable from MTA-A

        3. MTA-B is a primary RELAY-MTA (not relevant in this example)

        4. MTA-B has the highest priority.

        5. MTA-B doesn't have specific service type lines documented.
           MTA-A chooses public X.25, since it is the only possibility
           to connect to MTA-B.

        6. No other service types are available if the connection
           fails.

        7. MTA-C has a priority of 80, it is not a backup RELAY-MTA.
           MTA-A must spool the message and try to connect directly to
           MTA-B.

   The organisation running MTA-A could save money by sending messages
   for the MHS domain P=REMOTE; A=ARCOM; C=CH; via MTA-C.  Since the
   connection between MTA-C and the destination MTA-B is also expensive,
   the organisation running MTA-C would have to pay for external relay
   traffic.  Setting a lower priority for MTA-C forces the other RELAY-
   MTAs with public X.25 connectivity to take their share of the cost.

   Note that forcing other RELAY-MTAs to use a specific stack should be
   avoided wherever possible by offering RELAY-MTAs with equal priority
   for all mandatory network services.  This can be an important
   financial issue for MHS communities spanning several organisations,
   it is not relevant in general for an MHS community within a single
   organisation.

6.2 How to use RELAY-MTA-priorities for backup RELAY-MTAS

   Two RELAY-MTAs offer real backup connectivity for the MHS domain
   P=REMOTE; A=ARCOM; C=CH;.  It is therefore possible to set RELAY-MTA
   priorities in the range of 0..49 for both RELAY-MTAs.  MTA-B will be
   the preferred one since it has the higher priority.  If the
   connection to MTA-B fails, a sending RELAY-MTA may immediately try to
   connect to MTA-C.

      Community: REMOTEmail
      Domain: * P=REMOTE; A=ARCOM; C=CH;
      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-B; 10



Eppenberger                                                    [Page 20]

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      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-C; 30

                                       __________________________
      +-------+             +-------+ (                          )
      | MTA-A +-------------+ MTA-B +-( P=REMOTE; A=ARCOM; C=CH; )
      +-------+             +-------+ (__________________________)
               \                     /
                \           +-------+
                 -----------+ MTA-C |
                            +-------+

6.3 Load Sharing

   It is possible to set equal priorities to do some sort of load
   sharing.  However, most implementations are not able to do random
   selection of RELAY-MTAs with equal priorities but have a fixed
   configuration.  If load sharing is really needed then it is suggested
   to split up the MHS domain into several MHS subtrees and document
   them separately with a set of RELAY-MTAs with different priorities.

   An example is provided for illustration of the first possibility with
   equal RELAY-MTA-priorities:

      Community: REMOTEmail
      Domain: * P=REMOTE; A=ARCOM; C=CH;
      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-B; 10
      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-C; 10
          _               __________________________
           )  +-------+  (                          )
           )--+ MTA-B +--( P=REMOTE; A=ARCOM; C=CH; )
           )  +-------+  (__________________________)
           )            /
           )  +-------+/
           )--+ MTA-C |
          _)  +-------+

      And here is an example where the MHS domain
    C=CH;ADMD=ARCOM;PRMD=REMOTE;O=Big-Org is documented with its own
    DOMAIN document: Note that in this example both RELAY-MTAs serve
    as backup RELAY-MTAs.

      Community: REMOTEmail
      Domain: * P=REMOTE; A=ARCOM; C=CH;
      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-B; 10
      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-C; 30

      Community: REMOTEmail
      Domain: * O=Big-Org; P=REMOTE; A=ARCOM; C=CH;



Eppenberger                                                    [Page 21]

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      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-C; 10
      RELAY-MTA: P=REMOTE; A=ARCOM; C=CH;MTAname=MTA-B; 30
          _               __________________________
           )  +-------+  (                          )
           )--+ MTA-B +--( P=REMOTE; A=ARCOM; C=CH; )
           )  +-------+  (__________________________)
           )           \/
           )           /\ _____________________________________
           )  +-------+  (                                     )
           )--+ MTA-C |--( O=Big-Org; P=REMOTE; A=ARCOM; C=CH; )
          _)  +-------+  (_____________________________________)

7. Open issues

   Currently there are about 35 RELAY-MTAs within the COSINE-MHS
   service.  A rough guess is that a network with about 60 RELAY-MTAs is
   still manageable provided there are automated tools for MTA
   configuration.  If there are more MTAs applying for RELAY-MTA status
   in an MHS community, then either an X.500 based solution should be
   ready or a core set of about 30 well operated super-RELAY-MTAs should
   form a backbone, documented within a specific MHS community.

   Since the RELAY-MTA document contains information about the supported
   X.400 version (84 or 88), it is possible for an X.400(88) system to
   select with higher priority an (88)RELAY-MTA.  The rules in chapter 6
   could be modified to select X.400(88) systems first if the sending
   RELAY-MTA is an (88) system itself.  The issue of how to establish an
   X.400(88) RELAY-MTA infrastructure within an MHS community is for
   further study.






















Eppenberger                                                    [Page 22]

RFC 1465        Routing Coordination for X.400 Services         May 1993


Appendix A:  Document examples for the COSINE-MHS community

   Instead of creating artificial documents to show an example document
   set, this appendix contains extracts from a real operational X.400
   service.  The research and development community in Europe has used
   X.400 for several years.  This proposal was initially written to
   address this community only and solve the urgent routing and
   coordination problems.  Contributions from different experts have
   made it more flexible and therefore hopefully useful for other MHS
   communities.

Appendix A1:  The COMMUNITY document

  Community: COSINE-MHS
  # The COSINE-MHS service is a MHS community formed by the European
  # academic and research networks with additional contacts in all
  # other continents.
  #
  # The coordination is done by the COSINE-MHS project team.
  #
  Update: FORMAT=V3; DATE=921218; START=930201
  #
  Address: S=Project-Team; O=SWITCH; P=SWITCH; A=ARCOM; C=CH;
  #
  Phone: +41 1-262-31-43
  Fax:   +41 1-261-81-88
  #
  Mail:  SWITCH Head Office /
         MHS Coordination Service /
         Limmatquai 138 /
         CH-8001 Zurich /
         Switzerland
  #
  Reachable: 09:00-12:00; 14:00-17:30; UTC+1
  #
  Mail-server: S=mhs-server; O=switch; OU1=nic;
               P=SWITCH; A=ARCOM; C=CH;
  FTP-server:  nic.switch.ch; cosine; user@domain
  #
  Macro: Int-X25(80)        TELEX+00728722+X.25(80)+01+
  Macro: Internet-RFC-1006  TELEX+00728722+RFC-1006+03+
  Macro: IXI                TELEX+00728722+X.25(80)+06+
  #
  Mandatory-Service: Public-X.25/X.25/TP0
  # The public X.25 network.  X.25 is supported in most X.400
  # applications and mandatory in X.400 anyhow.
  #
  Mandatory-Service: Internet/TCP/RFC1006



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  # The Internet, standing for the global TCP/IP network of the
  # research and development community
  # RFC1006 is considered a solution to ease migration to OSI. It will
  # be replaced by TP4/CLNS as soon as a reliable service is
  # available.
  #
  Optional-Service: Int-CLNS/CLNS/TP4
  # The RARE Connectionless pilot service.  Current participants are
  # NORDUnet, SURFnet, CERN, NSFnet and SWITCH.
  #
  Optional-Service: EMPB-X.25/X.25/TP0
  # The International X.25 Infrastructure covering most countries in
  # Europe.  The absence of volume tariffs make it a preferred choice.

Appendix A2:  Example of a RELAY-MTA document

  Community: COSINE-MHS
  #
  Update: FORMAT=V3; DATE=921218; START=930201
  #
  RELAY-MTA: P=SWITCH; A=ARCOM; C=CH; MTAname=chx400.switch.ch
  #
  Status: primary
  #
  Password: none
  RTS-dialog-mode: MONOLOGUE
  #
  Called-address:  Public-X.25/X.25/TP0;
                   "591"/Int-X25(80)=22847971014520+CUDF+03010100;
                   MTS-TP-84
  Calling-address: Public-X.25/X.25/TP0;
                   Int-X25(80)=22847971014520;
  #
  Called-address:  Internet/TCP/RFC1006;
                   "591"/Internet-RFC-1006=chx400.switch.ch;
                   MTS-TP-84
  Calling-address: Internet/TCP/RFC1006;
                   Internet-RFC-1006=chx400.switch.ch
  #
  Called-address:  EMPB-X.25/X.25/TP0;
                   "591"/IXI=20432840100520+CUDF+03010100;
                   MTS-TP-84
  Calling-address: EMPB-X.25/X.25/TP0;
                   IXI=20432840100520;
  #
  Calling-address: Int-CLNS/CLNS/TP4;
                   "591"/NS+39756F11111111010000014560AA00040005E100;
                   MTS-TP-84



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  Called-address:  DCC+756+x11111111010000014560AA00040005E100
  #
  # For X.400(88) over CLNS
  #
  Calling-address: Int-CLNS/CLNS/TP4;
                   "592"/NS+39756F11111111010000014560AA00040005E100;
                   MTS-T
  Called-address:  DCC+756+x11111111010000014560AA00040005E100
  #
  System: HW=SUN 4/690MP; OS=SunOS 4.1.1; SW=PP-6.0
  #
  LocalDomain: O=switch; OU1=chx400; P=switch; A=arcom; C=ch;
  #
  EchoServer:  S=echo; O=switch; OU1=chx400; P=switch; A=arcom; C=ch;
  #
  Administrator: CN=Felix Kugler, O=SWITCH, C=CH
  Administrator: CN=Christoph Graf, O=SWITCH, C=CH

Appendix A3:  Example of a DOMAIN document

  Community: COSINE-MHS
  #
  Update: FORMAT=V3; DATE=921218; START=930201
  ##
  Domain: *     P=SWITCH; A=ARCOM; C=CH;
  Domain: *     P=SANDOZ; A=ARCOM; C=CH;
  Domain: *        P=ABB; A=ARCOM; C=CH;
  Domain: *        P=UBS; A=ARCOM; C=CH;
  Domain: *      P=ISREC; A=ARCOM; C=CH;
  Domain: *    P=ALCATEL; A=ARCOM; C=CH;
  Domain: *        P=ITU; A=ARCOM; C=CH;
  Domain: * P=OSILABMAIL; A=ARCOM; C=CH;
  Domain: *        P=WHO; A=ARCOM; C=CH;
  Domain: *       P=CERN; A=ARCOM; C=CH;
  Domain: *   P=CERBERUS; A=ARCOM; C=CH;
  #
  Administrator: CN=Christoph Graf, O=SWITCH, C=CH
  Administrator: S=postmaster; O=SWITCH; P=SWITCH; A=ARCOM; C=CH;
  #
  RELAY-MTA: P=SWITCH; A=ARCOM; C=CH; MTAname=chx400.switch.ch; 0
  #
  RELAY-MTA: P=SWITCH; A=ARCOM; C=CH; MTAname=vms.switch; 10

Appendix A4:  Example of a PERSON document

  Community: COSINE-MHS
  #
  Update: FORMAT=V3; DATE=921218; START=930201



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RFC 1465        Routing Coordination for X.400 Services         May 1993


  #
  Key: CN=Christoph Graf, O=SWITCH, C=CH
  #
  Name:    Christoph Graf
  #
  Address: S=Graf; O=SWITCH; P=SWITCH; A=ARCOM; C=CH;
  RFC822:  Graf@switch.ch
  #
  Phone:   +41 1 2565454
  Fax:     +41 1 2618133
  #
  Mail:    SWITCH Head Office /
           Christoph Graf /
           Limmatquai 138 /
           CH-8001 Zurich /
           Switzerland
  #
  Reachable: 09:00-12:00; 14:00-17:30; UTC+0100

































Eppenberger                                                    [Page 26]

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Appendix B:  BNF Definitions

       ::= "Called-address: " \
                             "; " \
                             "; "  \
                            ["; " ] 

       ::= "Calling-address: " \
                             "; " \
                             

       ::= "RTS-checkpoint-size: " \
                            'checkpoint size' 

       ::=  \
                             \
                            

       ::=  \
                            [{}] \
                            {}

       ::= "Community: " \
                            ('community name' | ) 

       ::=   \
                            {}\
                            [] \
                            [] \
                            []

       ::= {} \
                            {[]}

       ::= {"Administrator: "  }

       ::=    \
                              

       ::= 'Two Character Country Code ISO-3166'

       ::= "RTS-dialog-mode: " \
                            ("TWA" | "MONOLOGUE") 

       ::= 'Distinguished Name'

       ::=  \
                             \



Eppenberger                                                    [Page 27]

RFC 1465        Routing Coordination for X.400 Services         May 1993


                            

      ::= {}  \
                            {}

       ::= "Domain: "   

       ::= "EchoServer: "  

       ::= "Address: "  

       ::= "Mail-server: " 

       ::= 'local extension'

       ::= "Fax: "  

       ::=  [{}] \
                            [{]}

       ::= "FTAM-server: "  "; "\
                            'account-name' ["; " 'password'] \
                            ["; X.500 " ] 

       ::= "FTP-server: " 'domain name' "; " \
                            'account-name' ["; " 'password'] 

       ::= 'international prefix'

       ::= "LocalDomain: "  

       ::= "Macro: " 'Macro name' " " \
                            'Macro value' 

       ::= "Mail: " 'postal address information' 

       ::= "Mandatory-Service: " \
                             

       ::= ["O=" 'Organization-name' "; "] \
                            ["OU1="'OrganizationalUnit'"; "\
                            ["OU2=" 'OrganizationalUnit' "; " \
                            ["OU3=" 'OrganizationalUnit' "; " \
                            ["OU4=" 'OrganizationalUnit' "; "]]]] \
                            ["P=" 'PRMDname' "; "] \
                            "A=" 'ADMDname' "; " \
                            "C="  ";"




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       ::= "MTS-T" | "MTS-TP" | "MTS-TP-84"

        ::= "Name: " 'name of person' 

       ::= 'national telephone number'

       ::= 'Name of a network'

       ::= 'Name of a network service'

       ::= "Reachable: "  { "-"  "; "} \
                             

       ::= "Optional-Service: " \
                             

       ::=  ( "* " | "= " )

       ::= 'String encoded Presentation Address'

       ::= "Password: " \
                            ("secret" | "none" | \
                            "value=\"" 'password' "\"") 

       ::=  \
                             \
                             \
                            

       ::= "Key: "  

      ::=  {} {} \

       ::= "Phone: "  

       ::=         "Relay: " \
                            'UniqueRELAY-MTAkey' "; " \
                             

       ::=  \
                             \
                             \
                            

       ::=   \
                            

       ::= \



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RFC 1465        Routing Coordination for X.400 Services         May 1993


                            "RELAY-MTA: "  

       ::= 

       ::= {"Administrator: "  }

       ::= "RFC822: "  

       ::=  \
                            [ ]

       ::= 'Integer 0..99'

       ::=  "/" \
                             "/" \
                            

       ::= "Status: " ("primary" | "secondary") 

       ::= "System: HW=" 'computer type' "; " \
                            "OS=" 'operating system' "; " \
                            "SW=" 'MHS  software' 

       ::=  [{"; " }]

       ::=  {"+"  " "  \
                            [" x" ]}

       ::= 'hh:mm'

       ::= ("UTC+" | "UTC-") 'hhmm'

       ::= 'Name of a transport protocol'

       ::= ( |  )

       ::= (([ "P=" 'PRMDname' "; " ] \
                            ["A=" 'ADMDname' "; " ] \
                            "C="  "; " \
                            "MTAname=" 'MTAname')
                            |  )

       ::= "Update: FORMAT=V3; DATE=" 'yymmdd' \
                            "; START=" 'yymmdd' \
                            ["; END=" 'yymmdd'] 

       ::= "RTS-window-size: " \
                            'window size' 



Eppenberger                                                    [Page 30]

RFC 1465        Routing Coordination for X.400 Services         May 1993



       ::= 'OR address, ISO 10021-2 Annex F'

       ::= \
                             \
                            {  } \
                            {  } \
                            {  }

Security Considerations

   Security issues are not discussed in this memo.

Author's Address

   Urs Eppenberger
   SWITCH Head Office
   Limmatquai 138
   CH-8001 Zurich
   Switzerland

   Phone: +41 1 261 8112
   Fax:   +41 1 261 8133

   EMail: Eppenberger@switch.ch
          S=Eppenberger; O=SWITCH; P=SWITCH; A=ARCOM; C=CH;

   Comments to the document may also be sent to the distribution list
   wg-msg@rare.nl of the RARE Working Group on Mail and Messaging.






















Eppenberger                                                    [Page 31]