As per Relevance of the word multicast, we have this rfc below:
Network Working Group H.
Request for Comments: 3091 University of
Category: Informational 1 April 2001
Pi Digit Generation
Status of this
This memo provides information for the Internet community. It
not specify an Internet standard of any kind. Distribution of
memo is unlimited
Copyright
Copyright (C) The Internet Society (2001). All Rights Reserved
This memo defines a protocol to provide the Pi digit
service (PIgen) used between clients and servers on host computers
This protocol is intended to provide the Pi digit generation
(PIgen), and be used between clients and servers on host computers
Typically the clients are on workstation hosts lacking local
support, and the servers are more capable machines with greater
calculation capabilities. The essential tradeoff is the use
network resources and time instead of local computational cycles
The key words "MUST", "MUST NOT", "REQUIRED", "SHALL", "SHALL NOT",
"SHOULD", "SHOULD NOT", "RECOMMENDED", "MAY", and "OPTIONAL" in
document are to be interpreted as described in RFC 2119 [RFC2119].
All digits supplied by implementations of this service are
[US-ASCII] representations of decimal (base 10) numbers following
decimal point in values or approximations of Pi. There MUST be
implied decimal value of 3 (three) preceding the values provided
the service defined by this protocol
1. TCP Based Digit Generator
One REQUIRED PIgen service is defined as a stateless TCP service.
server listens on TCP port 314159. Once a connection is
the server sends a stream of data, one digit of Pi at at time
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RFC 3091 Pi Digit Generation Protocol 1 April 2001
starting with the most significant digit following the decimal point
Any incoming data MUST be discarded. This continues until the
closes the connection
The data flow over the connection is limited by the normal TCP
control mechanisms, so there is no concern about the server
data faster than the client can process it
Servers MAY use any appropriate method of Pi digit generation
provide this service, including (but not limited to) table
[DIGITS], numerical calculation [FIBPI,PIFFT] and
sampling [MCM]. However, the method chosen SHOULD provide a
value for the digits of Pi generated
Implementors of PIgen MUST provide this service to be
compliant with this RFC
1.1. Approximate
An OPTIONAL PIgen service is defined as a stateless TCP service.
server listens on TCP port 220007. Once a connection is
the server sends a stream of data, one digit of the rational
22/7 at a time, starting with the most significant digit
the decimal point. Any incoming data MUST be discarded.
continues until the client closes the connection
2. UDP Based Digit Generator
An OPTIONAL PIgen service is defined as a stateless UDP service.
server listens on UDP port 314159. When a datagram requesting
specific digit of Pi is received, an answering datagram is
containing the value of the requested digit of Pi according to
format defined in sections 2.1.1. and 2.1.2.
The requested digit value MAY be determined by any appropriate
of Pi digit generation. RECOMMENDED methods include table
[DIGITS], or numerical calculation [BBPPA].
2.1. Packet
The datagram-based components of the PIgen protocol suite all
the following UDP data payload formats (defined in the ABNF of
2234 [RFC2234]).
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RFC 3091 Pi Digit Generation Protocol 1 April 2001
2.1.1. Request Payload
request = nth_
nth_digit = 1*DIGIT ; specifying the n-th digit following
; decimal
2.1.2. Reply Payload
reply = nth_digit ":" DIGIT ; where DIGIT is the value of the n-
; digit following the
;
2.2. Approximate
An OPTIONAL PIgen service is defined as a stateless UDP service.
server listens on UDP port 220007. When a datagram requesting
specific digit of the rational number 22/7 is received, an
datagram is sent containing the value of the requested digit of 22/7
according to the format defined in sections 2.1.1. and 2.1.2.
3. IP Multicast Based Digit Generator
An OPTIONAL PIgen service is defined as a stateless UDP service.
random distribution of digits of Pi are sent using the payload
described in section 2.1.2. to the IP multicast
314.159.265.359.
There is no request structure. If a server implementing
component of the protocol suite joins the PIgen multicast group
does not detect a server providing digits within 30 seconds, it
elect to become the PIgen multicast provider
The PIgen multicast provider generates a random distribution of
digits of Pi and sends them out to the multicast group.
multicast clients build up a coherent value of Pi by listening to
multicast group over time
The randomly selected digit value MAY be determined by
appropriate method of Pi digit generation. RECOMMENDED
include table lookup [DIGITS], or numerical calculation [BBPPA].
ensure an adequately random distribution, a proper random
generator should be used, see [RANDOM] for some examples
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RFC 3091 Pi Digit Generation Protocol 1 April 2001
4. Service
Clients SHOULD discover PIgen servers via the DNS SRV
[RFC2782]. The service used is "pigen" and the protocols used
"tcp" and "udp". Approximate services (sections 1.1. and 2.2.)
should be discovered using a service of "pigem". This allows
central administration of addressing, fallback for failed relays
collectors, and static load balancing
5. Security
As almost every secure Internet protocol requires a highly
value of Pi in order to function correctly, it is imperative
clients only use a trusted PIgen server. The imminent collapse
the Internet is assured if this guideline is not strictly followed
6.
[RFC2119] Bradner, S., "Key words for use in RFCs to
Requirement Levels", BCP 14, RFC 2119, March 1997.
[US-ASCII] Coded Character Set--7-Bit American Standard Code
Information Interchange, ANSI X3.4-1986.
[DIGITS] ftp://pi.super-computing.org/pub/
[FIBPI] Pi and the Fibonacci
http://www.mcs.surrey.ac.uk/Personal/R.Knott/Fibonacci
fibpi.
[PIFFT] Pi Calculation based on FFT and AGM http://momonga.t.u
tokyo.ac.jp/~ooura/pi_fft.
[MCM] The Monte Carlo
http://www.daimi.aau.dk/~u951581/pi/MonteCarlo/pimc.
[BBPPA] Bailey-Borwien-Plouffe Pi
http://www.mathsoft.com/asolve/plouffe/plouffe.
[RFC2234] Crocker, D. and P. Overell, "Augmented BNF for
Specifications: ABNF", RFC 2234, November 1997.
[RANDOM] Randomness for Crypto http://www.cs.berkeley.edu/~daw/rnd
[RFC2782] Gulbrandsen, A., Vixie, P. and L. Esibov, "A DNS RR
specifying the location of services (DNS SRV)", RFC 2782,
February 2000.
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RFC 3091 Pi Digit Generation Protocol 1 April 2001
[CHARGEN] Postel, J., "Character Generation Protocol", STD 22,
864, May 1983.
7. Author's
Hugh
University of
2281 Bonisteel Blvd
Ann Arbor, MI 48109-2099
EMail: kennedyh@engin.umich.
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RFC 3091 Pi Digit Generation Protocol 1 April 2001
Full Copyright
Copyright (C) The Internet Society (2001). All Rights Reserved
This document and translations of it may be copied and furnished
others, and derivative works that comment on or otherwise explain
or assist in its implementation may be prepared, copied,
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