📄 rfc1069.txt
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RFC 1069 IP ISO Addressing February 1989
The Authority and Format Identifier (AFI) is "47" (BCD). The Initial
Domain Identifier (IDI) consists of the International Code Designator
(ICD) assigned to the Internet, and must contain the value "0006".
The Version Number must contain the value "02". The Global Area
Number must contains the value "00". The Padding field is of
variable length, but must contain the value zero.
4. Specific Values for use with the IGP specific field
In general, a particular routing domain may specify any addressing
scheme for use with the IGP specific part of the address, up to 11
octets in length (consistent with the maximum address length of 20
octets). However, it is expected that initially addresses used in
this field will consist of either the current IP addresses, or
addresses conformant with those specified in the draft ANSI proposal
for intra-domain routing.
For end systems which are members of routing domains using the IP
addresses for internal routing, the addresses will look as follows:
Callon & Braun [Page 6]
RFC 1069 IP ISO Addressing February 1989
Octet
+------------------------+
| AFI | 1
+------------------------+
| IDI / ICD | 2
+-- --+
|(specifies DoD Internet)| 3
+------------------------+
| Version Number | 4
+------------------------+
| Global Area | 5
+--- ---+
| Number | 6
+------------------------+
| Routing | 7
+--- ---+
| Domain | 8
+------------------------+
| | 9
: Padding : :
: : :
| | 15
+------------------------+
| Four Octet | 16
+--- ---+
| Internet | 17
+--- ---+
| DoD | 18
+--- ---+
| Address | 19
+------------------------+
| Selector | 20
+------------------------+
Figure 3: ISO IP Address with Encoded DoD IP Address
For end systems which are members of routing domains using the
address format specified in the draft ANSI proposal for intra-domain
routing [6], the addresses will look as follows:
Callon & Braun [Page 7]
RFC 1069 IP ISO Addressing February 1989
Octet
+------------------------+
| AFI | 1
+------------------------+
| IDI / ICD | 2
+-- --+
|(specifies DOD Internet)| 3
+------------------------+
| Version Number | 4
+------------------------+
| Global Area | 5
+--- ---+
| Number | 6
+------------------------+
| Routing | 7
+--- ---+
| Domain | 8
+------------------------+
| | 9
+--- ---+
| Padding | 10
+--- ---+
| | 11
+------------------------+
| | 12
+--- LOC-AREA ---+
| | 13
+------------------------+
| | 14
: ID : :
: : :
| | 19
+------------------------+
| Selector | 20
+------------------------+
Figure 4: ISO IP Address with Encoded ANSI-format Address
5. Devices Attached to PDNs
Otherwise isolated end systems, which are attached to the Internet
only indirectly via public data networks, and simple LANs which are
similarly attached only via Public Data Networks, may make use of a
separate address format based on their X.121 address. Such addresses
may, for example, use the ISO-X.121 address format discussed in [3].
These addresses will need to be handled for routing purposes in much
the same way as addresses in routing domains which have been
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RFC 1069 IP ISO Addressing February 1989
interconnected to the Internet, but which use other address formats,
such as those specified by national standards bodies.
6. Migration to Future Routing Protocols
Initially, routing of ISO datagrams in the Internet may make use of
the first 8 octets of the address (AFI, ICD, version, global area
number, and routing domain number) as a flat field identifying the
routing domain. This implies that if EGP is initially used for
routing between routing domains, a new version of EGP may be required
to carry 8 octet routing domain numbers instead of 3 octet network
numbers.
There are currently several efforts underway to determine the
requirements for inter-autonomous system routing, and to define a new
protocol. One of the requirements of inter-autonomous system routing
is the need to be able to deal with a very large Internet. It is
anticipated that during the lifetime of the addressing scheme
described in this RFC the number of networks in the Internet will
grow to the point where it is no longer feasible for any gateway to
maintain separate routes to every network in the Internet. Allowing
inter-domain routing to be done by routing domain number instead of
network number is therefore a necessary step in the long term.
It is difficult to anticipate the rate at which the number of routing
domains may grow. For example, during a period of time in which the
number of networks grows by a factor of 100, it is not clear whether
the number of routing domains may also be expected to grow by a
factor of 100, or by some lesser amount. It is possible that the
number of routing domains will also grow to a point where it is not
feasible for a single gateway to maintain separate routes to each.
In order to prepare for this eventuality, we have provided for a
"global area" field.
In the long term, it will be necessary for gateways to route to
destinations which are in routing domains utilizing other addressing
formats, specified by other organizations such as ANSI, ECMA, etc.
In this case, it will not be possible to ensure that the first 8
octets of the address specifies the routing domain. In the long
term, it will therefore be necessary to route based on variable
length routing domain identifiers. It may be assumed that future
inter-domain routing protocols will allow for specification of either
(1) an address mask, specifying which part of an address is relevant
for specifying those destinations which are reachable via a
particular domain; or (2) a length field, specifying how many leading
octets in a particular address are relevant. Specification of the
details of such a routing protocol is beyond the scope of this
document.
Callon & Braun [Page 9]
RFC 1069 IP ISO Addressing February 1989
References
[1] ISO, "Protocol for Providing the Connectionless-Mode Network
Services", RFC-926, ISO, December 1984.
[2] ANSI, "Guidelines for the Specification of the Structure of the
Domain Specific Part (DSP) of the ISO Standard NSAP Address",
RFC-982, ANSI Working Document X3S3.3/85-258, April 1986.
[3] ISO, Draft International Standard 8348/DAD2, "Information
Processing Systems -- Data Communications -- Network Service
Definition, Addendum 2 Covering Network Layer Addressing", RFC-
941, April 1985.
[4] Reynolds, J. and J. Postel, "Assigned Numbers", RFC-1010,
USC/Information Sciences Institute, May 1987.
[5] Callon, R. and H. W. Braun, "Working Draft -- Guidelines for the
use of Internet-IP addresses in the ISO Connectionless-Mode
Network Protocol," RFC-986, June 1986.
[6] ISO TC97/SC6/WG2 working document, "Intermediate System to
Intermediate System Intra-Domain Routing Exchange Protocol".
Callon & Braun [Page 10]
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