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Annotation of coherent/d/bin/mail/smail/docs/Domains, revision 1.1

1.1     ! root        1:              WHAT YOU NEED TO KNOW ABOUT PATHALIAS
        !             2:           AND WHAT PATHALIAS NEEDS TO KNOW ABOUT YOU
        !             3:                               or
        !             4:                   HOW PATHALIAS MAKES DOMAINS
        !             5: 
        !             6:                        Christopher Seiwald
        !             7: 
        !             8: This note describes the host connectivity data and domain data
        !             9: needed to effect UUCP domain-style address routing.  This
        !            10: describes mostly the domain data, but also discusses how to
        !            11: distribute connectivity data.  Look elsewhere for a discussion of
        !            12: domains.
        !            13: 
        !            14: Briefly, the connectivity data (what's in mod.map) connects
        !            15: all hosts in the UUCP network into one big directed graph, and
        !            16: the domain data superimposes a domain tree onto that graph.
        !            17: Pathalias converts these two sets of data into a routing database
        !            18: which smail/rmail, a UUCP mail routing program, uses.
        !            19: 
        !            20: 1.  Domains and Gateways for UUCP
        !            21: 
        !            22: For domains in the UUCP zone, the top of a subdomain is all
        !            23: gateway hosts for that domain; the top of the UUCP zone will
        !            24: probably be nearly a hundred hosts.  As a transition aid, we
        !            25: also consider an individual host at the bottom of the domain tree a
        !            26: subdomain "host.UUCP", with one gateway and no further subdomains.  
        !            27: (We expect to phase this out eventually.)
        !            28: 
        !            29: A gateway host for a domain must do four things:
        !            30:        I)      Pass mail bound for that domain to the
        !            31:                appropriate host.
        !            32:        II)     Pass mail bound for outside that domain to a
        !            33:                gateway in the parent domain.
        !            34:        III)    Pass mail bound for a subdomain to a gateway of
        !            35:                that subdomain.
        !            36:        IV)     Recognise the domain!user address syntax.
        !            37: 
        !            38: smail/rmail already provides (IV).  With the data described here,
        !            39: pushed through pathalias, smail/rmail can then provide (I)-(III).
        !            40: 
        !            41: 2.  The Zone Registry
        !            42: 
        !            43: For any sizeable zone, one gateway host supports the zone registry.
        !            44: For other zones, such as BITNET, CSNET, DDN, etc., registries are
        !            45: supported, using conventions appropriate to those zones.  Contact
        !            46: electronic mail addresses are supported for queries, and updates to
        !            47: configuration information may also be handled via mail.  In the UUCP
        !            48: zone, the id's "[email protected]" and "[email protected]"
        !            49: serve to collect the connectivity and domain data, respectively, for
        !            50: that zone.
        !            51: 
        !            52: The registry for a zone speaks for that zone, communicating
        !            53: chiefly with its peers, the registry of the parent domain, and
        !            54: the registries of the subdomains.
        !            55: 
        !            56: 3.  Functions of Domain Data
        !            57: 
        !            58: Each gateway for a domain must map the domain-style names into
        !            59: the UUCP host names for all hosts of the domain.  This host name
        !            60: mapping provides (I) above.
        !            61: 
        !            62: Each gateway for a domain knows a) at least one gateway for each
        !            63: immediate subdomain, and b) at least one gateway host of the
        !            64: parent domain.  This provides (II) and (III) above.
        !            65: 
        !            66: For consistency across the gateways of a domain, each gateway for
        !            67: the domain should know a) ALL gateways for each immediate
        !            68: subdomain; and b) ALL gateways for the parent domain.  Pathalias
        !            69: will pick the closest. In this way, one single database can
        !            70: describe the domain structure for all gateways on a domain,
        !            71: without variations for each gateway. 
        !            72: 
        !            73: In order to aid routing and avoid overloading the parent gateway,
        !            74: gateways should also know most gateways for peer level domains.
        !            75: This information is also provided by the map and used by pathalias.
        !            76: When a new peer domain is created, traffic can be routed through the
        !            77: parent (which must be updated immediately) until information about
        !            78: the peer can be propagated.
        !            79: 
        !            80: Additionally, a gateway could know about domains more than one
        !            81: level above or below it so that mail doesn't stop for address
        !            82: resolution at every gateway along its path.
        !            83: 
        !            84: 4.  Format of Domain Data
        !            85: 
        !            86: 4.1  Host Name List
        !            87: 
        !            88: The host name list aliases the domain style address of a host to
        !            89: the UUCP host name.  The pathalias input format is:
        !            90: 
        !            91:                uucp-name .domain-name[, ...]
        !            92: 
        !            93: The .UUCP suffix is implicit in the uucp-name (smail/rmail does
        !            94: this), and is not needed.
        !            95: Upper/lower case doesn't matter in a dotted domain name.
        !            96: Examples:
        !            97:        
        !            98:                ihnp4 = .ATT.COM
        !            99:                ucbvax = .Berkeley.EDU
        !           100:                cbosgd = .osgd.cb.att.com, .cbosgd.att.com
        !           101: 
        !           102: Might produce from pathalias:
        !           103: 
        !           104:                ihnp4                   mtxinu!ihnp4!%s
        !           105:                .ihnp4.ATT.COM          mtxinu!ihnp4!%s
        !           106:                ucbvax                  ucbvax!%s
        !           107:                .Berkeley.EDU           ucbvax!%s
        !           108:                cbosgd                  cbosgd!%s
        !           109:                .osgd.cb.att.com        cbosgd!%s
        !           110:                .cbosgd.att.com         cbosgd!%s
        !           111: 
        !           112: A single host may have more than one domain style address; in
        !           113: fact, a host may be in several domains at once.  However, each
        !           114: host must have a single primary location in the domain tree,
        !           115: and other addresses should be viewed as transition aids.  For
        !           116: example, cbosgd might be known as cbosgd, cbosgd.UUCP,
        !           117: cbosgd.ATT.UUCP, cbosgd.btl.csnet, and cbosgd.ATT.COM, but
        !           118: the primary name is the one in the organizational domain (COM)
        !           119: which applies to all networks, and the others are temporary
        !           120: names for upward compatibility only.
        !           121: 
        !           122: 4.2  Domain Gateway List
        !           123: 
        !           124: The domain gateway list aliases the domain style address of a
        !           125: domain to the UUCP host name of the closest gateway of that
        !           126: domain.  This involves a trick in pathalias, and employs a
        !           127: extra network name domain-gw.  The pathalias input format is:
        !           128: 
        !           129:                domain-gw .domain-name
        !           130: 
        !           131: Again, the .UUCP suffix is implicit in the uucp-name, and is
        !           132: not needed.  
        !           133: Examples:
        !           134: 
        !           135:                decwrl .DEC.COM
        !           136:                decuac .DEC.COM
        !           137: 
        !           138:                cbosgd .ATT.COM
        !           139:                clyde .ATT.COM
        !           140: 
        !           141: Might generate from pathalias:
        !           142: 
        !           143:                .DEC.COM        seismo!decuac!%s
        !           144:                .ATT.COM        cbosgd!%s
        !           145: 
        !           146: Note that pathalias chooses the closest host from inside the {}'s.
        !           147: The (DEAD)'s prevent pathalias from following along the mock network
        !           148: called "domain-gw".
        !           149: 
        !           150: 5.  Distribution of Domain Data
        !           151: 
        !           152: A zone registry maintains a Host Name List (in the format of 4.1
        !           153: above) of all hosts within its domain and a Domain Gateway List
        !           154: (in the format of 4.2 above) of all gateways of the domain.
        !           155: 
        !           156: Up: A registry collects the Domain Gateway List from the registry
        !           157: of each of its subdomains, and transmits to the registry of its
        !           158: parent domain its own Domain Gateway List and, if it chooses, the
        !           159: Domain Gateway Lists of some or all of its subdomains.  Whether
        !           160: it includes lists from its subdomains depends on how important it
        !           161: considers them to the parent domain.
        !           162: 
        !           163: Down: Similarly, a registry collects the Domain Gateway List from
        !           164: the registry of its parent domain, and transmits to the registry
        !           165: of each of its subdomains its Domain Gateway List and the Domain
        !           166: Gateway List of its parent domain.  Note that the Domain Gateway
        !           167: List of the parent domain may include lists from the parent's
        !           168: other subdomains.
        !           169: 
        !           170: A registry may decide not to use the parent domain's Domain
        !           171: Gateway List or not to transmit it to its subdomains' registries.
        !           172: (This should be done only with the consent of the subdomains.) In
        !           173: this case, the registry must introduce a domain gateway alias for
        !           174: all top level domains, to ensure that all the mail gets delivered.
        !           175: 
        !           176: Across: a registry transmits to each of the gateways of its
        !           177: domain its Host Name List, its Domain Gateway List, and collected
        !           178: Domain Gateway Lists.  The registry also transmits to each normal
        !           179: host (one gateway, no subdomains) of its domain its Domain
        !           180: Gateway List.
        !           181: 
        !           182: Together, "up," "down," and "across" insure that each gateway has
        !           183: the Host Name List for its domain, and the Domain Gateway List of
        !           184: its own domain and at least its parent domain and subdomains.
        !           185: "Up" and "across" will probably take place on demand by mail.
        !           186: "Down" will probably be broadcast via netnews on a regular
        !           187: schedule.  In particular, the second level information for the UUCP
        !           188: zone (one entry per organization) and the complete top level domain
        !           189: information make up the postings to mod.map.
        !           190: 
        !           191: 6.  Distribution of Connectivity Data
        !           192: 
        !           193: The distribution of connectivity data will probably follow the
        !           194: path of domain data: registries passing connectivity data up,
        !           195: down, and across the domain tree, with the exception that the
        !           196: connectivity within a third (or lower) level domain will be
        !           197: discouraged from leaving the domain, so the data the UUCP zone
        !           198: registry distributes will include only the first and second
        !           199: level gateways.  Local information about internal subdomains and
        !           200: machines of organizations should not be included in globally
        !           201: published information, but rather distributed locally as needed.
        !           202: 
        !           203: 7.  Various Notes
        !           204: 
        !           205: The following are examples of data that should be joined together
        !           206: as input to pathalias.
        !           207: 
        !           208:        Parent Domain Gateway List
        !           209:        Parent Connectivity Data
        !           210:        This Level Domain Gateway List
        !           211:        This Level Host Name List
        !           212:        This Level Connectivity Data
        !           213:        Collected Subdomains' Domain Gateway Lists
        !           214:        Collected Subdomains' Connectivity Data
        !           215:        Private Additions
        !           216:        Alias for "this host"
        !           217: 
        !           218: This note does not describe the inclusion of private additions to
        !           219: the domain or connectivity data.
        !           220: 
        !           221: Because domain names intermix with host names (and the .UUCP
        !           222: suffix is implicit), you can address hosts known at your gateway
        !           223: as "uucp-host.UUCP".  We discourage this, because the address is 
        !           224: then particular to the sender's location.
        !           225: 
        !           226: 
        !           227:                /+\
        !           228: 5/1/85         +\      [email protected]
        !           229:                \+/
        !           230: 
        !           231: [Updated 5/9/86 by Mark Horton.]
        !           232: #
        !           233: #@(#)Domains   2.5 (smail) 9/15/87
        !           234: #

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