RFC 1526 (rfc1526) - Page 3 of 8

Assignment of System Identifiers for TUBA/CLNP Hosts

RFC 1526              System Identifiers for TUBA         September 1993


               _______________
               |_|___________________________________
               |AFI_|__IDI___|_______________________|
               |_47_|__0005__|DFI_|AA_|Rsvd_|_RD_|Area_|ID_|Sel_|
        octets |_1__|___2____|_1__|_3_|__2__|_2__|_2___|_6_|_1__|

                    Figure 2 (a): GOSIP Version 2 NSAP structure.
               ______________
               |_|_____________________________________
               |AFI_|__IDI__|_________________________|
               |_39_|__840__|DFI_|_ORG_|Rsvd_|RD_|Area_|_ID_|Sel_|
        octets |_1__|___2___|_1__|__3__|_2___|_2_|__2__|_6__|_1__|

                     IDP   Initial Domain Part
                     AFI   Authority and Format Identifier
                     IDI   Initial Domain Identifier
                     DSP   Domain Specific Part
                     DFI   DSP Format Identifier
                     ORG   Organization Name (numeric form)
                     Rsvd  Reserved
                     RD    Routing Domain Identifier
                     Area  Area Identifier
                     ID    System Identifier
                     SEL   NSAP Selector


                 Figure 2(b): ANSI NSAP address format for DCC=840

2.  Autoconfiguration

   There are provisions in OSI for the autoconfiguration of area
   addresses. OSI end systems may learn their area addresses
   automatically by observing area address identified in the IS-Hello
   packets transmitted by routers using the ISO 9542 End System to
   Intermediate System Routing Protocol, and may then insert their own
   system identifier. (In particular, RFC 1237 explains that when the ID
   portion of the address is assigned using IEEE style 48-bit
   identifiers, an end system can reconfigure its entire NSAP address
   automatically without the need for manual intervention.) End systems
   that have not been pre-configured with an NSAPA may also request an
   address from an intermediate system their area using [5].

2.1  Autoconfiguration and 48-bit addresses

   There is a general misassumption that the 6-octet system identifier
   must be a 48-bit IEEE assigned (ethernet) address.  Generally
   speaking, autoconfiguration does not rely on the use of a 48-bit
   ethernet style address; any system identifier that is globally



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