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This is a modified version of the Internet RFC suitable for machine-translating. Original version is available here: RFC795
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HISTORIC
Network Working Group                                          J. Postel
Request for Comments:  795                                           ISI
                                                          September 1981
                            SERVICE MAPPINGS
                            ----------------
This memo describes the relationship between the Internet Protocol (IP) [1] Type of Service and the service parameters of specific networks.

The IP Type of Service has the following fields:

Bits 0-2: Precedence. Bit 3: 0 = Normal Delay, 1 = Low Delay. Bits 4: 0 = Normal Throughput, 1 = High Throughput. Bits 5: 0 = Normal Relibility, 1 = High Relibility. Bit 6-7: Reserved for Future Use.
      0     1     2     3     4     5     6     7
   +-----+-----+-----+-----+-----+-----+-----+-----+
   |                 |     |     |     |     |     |
   |   PRECEDENCE    |  D  |  T  |  R  |  0  |  0  |
   |                 |     |     |     |     |     |
   +-----+-----+-----+-----+-----+-----+-----+-----+
111 - Network Control 110 - Internetwork Control 101 - CRITIC/ECP 100 - Flash Override 011 - Flash 010 - Immediate 001 - Priority 000 - Routine

The individual networks listed here have very different and specific service choices. RFC 795 Service Mappings
Postel                                                          [Page 1]

                                                          September 1981
AUTODIN II

The service choices are in two parts: Traffic Acceptance Catagories, and Application Type. The Traffic Acceptance Catagories can be mapped into and out of the IP TOS precedence reasonably directly. The Application types can be mapped into the remaining IP TOS fields as follows.
      TA    DELAY    THROUGHPUT    RELIABILITY
      ---   -----    ----------    -----------
      I/A     1           0             0
Q/R 0 0 0 B1 0 1 0 B2 0 1 1
      DTR    TA
      ---   ---
      000   Q/R
001 Q/R 010 B1 011 B2 100 I/A 101 I/A 110 I/A 111 error RFC 795 Service Mappings
Postel                                                          [Page 2]

                                                          September 1981
ARPANET

The service choices are in quite limited. There is one priority bit that can be mapped to the high order bit of the IP TOS precedence. The other choices are to use the regular ("Type 0") messages vs. the uncontrolled ("Type 3") messages, or to use single packet vs. multipacket messages. The mapping of ARPANET parameters into IP TOS parameters can be as follows.
      Type   Size   DELAY    THROUGHPUT    RELIABILITY
      ----   ----   -----    ----------    -----------
        0      S      1           0             0
0 M 0 0 0 3 S 1 0 0 3 M not allowed
      DTR   Type   Size
      ---   ----   ----
      000     0      M
001 0 M 010 0 M 011 0 M 100 3 S 101 0 S 110 3 S 111 error RFC 795 Service Mappings
Postel                                                          [Page 3]

                                                          September 1981
PRNET

There is no priority indication. The two choices are to use the station routing vs. point-to-point routing, or to require acknowledgments vs. having no acknowledgments. The mapping of PRNET parameters into IP TOS parameters can be as follows.
      Routing   Acks    DELAY    THROUGHPUT    RELIABILITY
      -------   ----    -----    ----------    -----------
        ptp      no       1           0             0
ptp yes 1 0 1
station no 0 0 0 station yes 0 0 1
      DTR   Routing   Acks
      ---   -------   ----
      000   station    no
001 station yes 010 station no 011 station yes 100 ptp no 101 ptp yes 110 ptp no 111 ptp yes

SATNET

There is no priority indication. The four choices are to use the block vs. stream type, to select one of four delay catagories, to select one of two holding time strategies, or to request one of three reliability levels. The mapping of SATNET parameters into IP TOS parameters can thus quite complex there being 2*4*2*3=48 distinct possibilities.

References ----------

[1] Postel, J. (ed.), "Internet Protocol - DARPA Internet Program
Protocol Specification," RFC 791, USC/Information Sciences Institute, September 1981.










Postel [Page 4]

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