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diff --git a/doc/rfc/rfc795.txt b/doc/rfc/rfc795.txt new file mode 100644 index 0000000..e13b2db --- /dev/null +++ b/doc/rfc/rfc795.txt @@ -0,0 +1,232 @@ + + +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. + + + + + + + + + + + + + + + + + +Postel [Page 1] + + + September 1981 +RFC 795 Service Mappings + + + +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 + + + + + + + + + + + + + + + + + + + + + + + + + +Postel [Page 2] + + + September 1981 +RFC 795 Service Mappings + + + +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 + + + + + + + + + + + + + + + + + + + + + + + + +Postel [Page 3] + + + September 1981 +RFC 795 Service Mappings + + + +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] + |