rfc1340.txt

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Reynolds & Postel				               [Page 28]

RFC 1340		    Assigned Numbers		       July 1992


			 IANA ETHERNET ADDRESS BLOCK

   The IANA owns an Ethernet address block which may be	used for
   multicast address asignments	or other special purposes.

   The address block in	IEEE binary is (which is in bit	transmission
   order):

		       0000 0000 0000 0000 0111	1010

   In the normal Internet dotted decimal notation this is 0.0.94 since
   the bytes are transmitted higher order first	and bits within	bytes
   are transmitted lower order first (see "Data	Notation" in the
   Introduction).

   IEEE	CSMA/CD	and Token Bus bit transmission order: 00 00 5E

   IEEE	Token Ring bit transmission order: 00 00 7A

   Appearance on the wire (bits	transmitted from left to right):

       0			   23				 47
       |			   |				 |
       1000 0000 0000 0000 0111	1010 xxxx xxx0 xxxx xxxx xxxx xxxx
       |				     |
       Multicast Bit			     0 = Internet Multicast
					     1 = Assigned by IANA for
						 other uses

   Appearance in memory	(bits transmitted right-to-left	within octets,
   octets transmitted left-to-right):

       0			   23				 47
       |			   |				 |
       0000 0001 0000 0000 0101	1110 0xxx xxxx xxxx xxxx xxxx xxxx
	       |		     |
	       Multicast Bit	     0 = Internet Multicast
				     1 = Assigned by IANA for other uses

   The latter representation corresponds to the	Internet standard bit-
   order, and is the format that most programmers have to deal with.
   Using this representation, the range	of Internet Multicast addresses
   is:

	  01-00-5E-00-00-00  to	 01-00-5E-7F-FF-FF  in hex, or

	  1.0.94.0.0.0	to  1.0.94.127.255.255	in dotted decimal




Reynolds & Postel				               [Page 29]

RFC 1340		    Assigned Numbers		       July 1992


			     IP	TOS PARAMETERS

   This	documents the default Type-of-Service values that are currently
   recommended for the most important Internet protocols.

   There are four assigned TOS values: low delay, high throughput, high
   reliability,	and low	cost; in each case, the	TOS value is used to
   indicate "better".  Only one	TOS value or property can be requested
   in any one IP datagram.

   Generally, protocols	which are involved in direct interaction with a
   human should	select low delay, while	data transfers which may involve
   large blocks	of data	are need high throughput.  Finally, high
   reliability is most important for datagram-based Internet management
   functions.

   Application protocols not included in these tables should be	able to
   make	appropriate choice of low delay	(8 decimal, 1000 binary) or high
   throughput (4 decimail, 0100	binary).

   The following are recommended values	for TOS:

		  -----	Type-of-Service	Value -----

      Protocol		 TOS Value

      TELNET (1)	 1000		      (minimize	delay)

      FTP
	Control		 1000		      (minimize	delay)
	Data (2)	 0100		      (maximize	throughput)

      TFTP		 1000		      (minimize	delay)

      SMTP (3)
	Command	phase	 1000		      (minimize	delay)
	DATA phase	 0100		      (maximize	throughput)

      Domain Name Service
	UDP Query	 1000		      (minimize	delay)
	TCP Query	 0000
	Zone Transfer	 0100		      (maximize	throughput)

      NNTP		 0001		      (minimize	monetary cost)







Reynolds & Postel				               [Page 30]

RFC 1340		    Assigned Numbers		       July 1992


      ICMP
	Errors		 0000
	Requests	 0000 (4)
	Responses	 <same as request> (4)

      Any IGP		 0010		      (maximize	reliability)

      EGP		 0000

      SNMP		 0010		      (maximize	reliability)

      BOOTP		 0000

      Notes:

      (1) Includes all interactive user	protocols (e.g., rlogin).

      (2) Includes all bulk data transfer protocols (e.g., rcp).

      (3) If the implementation	does not support changing the TOS during
      the lifetime of the connection, then the recommended TOS on
      opening the connection is	the default TOS	(0000).

      (4) Although ICMP	request	messages are normally sent with	the
      default TOS, there are sometimes good reasons why	they would be
      sent with	some other TOS value.  An ICMP response	always uses the
      same TOS value as	was used in the	corresponding ICMP request
      message.

   An application may (at the request of the user) substitute 0001
   (minimize monetary cost) for	any of the above values.




















Reynolds & Postel				               [Page 31]

RFC 1340		    Assigned Numbers		       July 1992


			 IP TIME TO LIVE PARAMETER

   The current recommended default time	to live	(TTL) for the Internet
   Protocol (IP) [45,105] is 64.















































Reynolds & Postel				               [Page 32]

RFC 1340		    Assigned Numbers		       July 1992


			 DOMAIN	SYSTEM PARAMETERS

   The Internet	Domain Naming System (DOMAIN) includes several
   parameters.	These are documented in	RFC-1034, [81] and RFC-1035
   [82].  The CLASS parameter is listed	here.  The per CLASS parameters
   are defined in separate RFCs	as indicated.

   Domain System Parameters:

      Decimal	Name					      References
      --------	----					      ----------
	     0	Reserved					   [PM1]
	     1	Internet (IN)					[81,PM1]
	     2	Unassigned					   [PM1]
	     3	Chaos (CH)					   [PM1]
	     4	Hessoid	(HS)					   [PM1]
       5-65534	Unassigned					   [PM1]
	 65535	Reserved					   [PM1]

   In the Internet (IN)	class the following TYPEs and QTYPEs are
   defined:


      TYPE	      value and	meaning

      A		      1	a host address				    [82]
      NS	      2	an authoritative name server		    [82]
      MD	      3	a mail destination (Obsolete - use MX)	    [82]
      MF	      4	a mail forwarder (Obsolete - use MX)	    [82]
      CNAME	      5	the canonical name for an alias		    [82]
      SOA	      6	marks the start	of a zone of authority	    [82]
      MB	      7	a mailbox domain name (EXPERIMENTAL)	    [82]
      MG	      8	a mail group member (EXPERIMENTAL)	    [82]
      MR	      9	a mail rename domain name (EXPERIMENTAL)    [82]
      NULL	      10 a null	RR (EXPERIMENTAL)		    [82]
      WKS	      11 a well	known service description	    [82]
      PTR	      12 a domain name pointer			    [82]
      HINFO	      13 host information			    [82]
      MINFO	      14 mailbox or mail list information	    [82]
      MX	      15 mail exchange				    [82]
      TXT	      16 text strings				    [82]

      RP	      17 for Responsible Person			   [172]
      AFSDB	      18 for AFS Data Base location		   [172]
      X25	      19 for X.25 PSDN address			   [172]
      ISDN	      20 for ISDN address			   [172]
      RT	      21 for Route Through			   [172]




Reynolds & Postel				               [Page 33]

RFC 1340		    Assigned Numbers		       July 1992


      NSAP	      22 for NSAP address, NSAP	style A	record	   [174]
      NSAP-PTR	      23 for domain name pointer, NSAP style	   [174]

      AXFR	      252 transfer of an entire	zone		    [82]
      MAILB	      253 mailbox-related RRs (MB, MG or MR)	    [82]
      MAILA	      254 mail agent RRs (Obsolete - see MX)	    [82]
      *		      255 A request for	all records		    [82]












































Reynolds & Postel				               [Page 34]

RFC 1340		    Assigned Numbers		       July 1992


			       BOOTP PARAMETERS

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