- By Initial Connection Protocol (ICP), I mean a third level protocol
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- which is initiated by a user process at one site in order to contact a
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- server process at another site. Typically, the user process will be a
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- Telnet and the server process will be a logger, but there may be other
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- cases.
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- In this RFC, I wish to describe a family of ICPs suitable for
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- establishing one pair of connections (one in each direction) between any
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- user process and any server process, and to propose further a particular
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- subset of this family as the standard ICP for connecting user processes
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- to loggers on systems which accept teletype-like devices.
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- Notation
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- We have no standard notation for describing system calls which initiate
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- and close connections or cause data to be sent, so I will use the
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- following ad hoc notation.
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- Init (local = l, foreign = f, size = s)
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causes the local Host to attempt to establish a connection between
socket l at the local Host and socket f, with a byte size of s for
the connection.
l is a 32 bit local socket number,
f is a 40 bit foreign socket number, the high-order eight bits
of which specify the foreign Host, and
s is an eight bit non-zero byte size.
The sum of l and f must be odd.
- Listen (local = l, size = s)
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causes the local Host to wait for a request for connection to local
socket l with byte size s. The process will be woken when a
connection is established. The parameters l and s are the same as
for Init.
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The data named by d is sent over the connection attached to local
socket l. l must be a send socket attached to a connection. d is the
name of a data area.
- Receive (socket = l, data = d)
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The receive side counterpart to send.
- Close (socket = l)
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Any connection currently attached to a local socket l is closed.
- A Family of ICPs
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- Briefly, a server process at a site attaches a well-advertised send
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- socket L and listens. A user process initiates connection to L from its
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- receive socket U. The byte size for this connection is 32. The server
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- process then transmits a 32-bit even number S and closes the connection.
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- The 32-bit number S and its successor, S+1, are the socket number the
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- server will use. The final steps are for sockets S and S+1 at the
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- server site to be connected to sockets U+1 and U respectively at the
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- user site.
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- Using the notation, the server executes the following sequence:
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Listen (socket = L, size = 32)
[Wait until a user connects]
Send (socket = L, data = S)
Close (socket = L)
Init (local = S, foreign = U+1, size = Bu)
Init (local = S+1, foreign = U, size = Bs)
- The user executes the following:
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Init (local = U, foreign = L, size = 32)
Receive (socket = U, data = S)
Close (socket = U)
Init (local = U+1, foreign = S, size = Bu)
Init (local = U, foreign = S+1, size = Bs)
- Note that L is a send socket (odd), while S and U are receive sockets
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- (even). Where L, S or U are used as values of local, they are 32-bit
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- numbers; where they are values of foreign, they are 40-bit numbers. The
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- parameters Bs and Bu are the byte sizes to be sent by the server and
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- user, respectively.
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- by the three numbers L, Bs and Bu, and must meet the restrictions that
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(a) L is a send socket,
(b) Bs and Bu are legal byte sizes, and
(c) for each L there is only on pair of associated byte sizes.
- This last restriction prevents two distinct services from being
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- available through the same socket and distinguished only by the byte
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- sizes.
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- Telnet ICP
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- For connecting teletype-like users, i.e. interactive and ASCII, to Hosts
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- serving such users, I propose an ICP of the form described above and
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- characterized by L = 1, Bs = Bu = 8. [There has been some confusion
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- about socket numbers. Here I specifically mean L = X00000001]
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- Formalities
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- I propose that the Telnet ICP be made official. Comments should be
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- published before the May NWG meeting, the subject will be discussed
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- there, and we will decide there to accept or reject this protocol.
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[ This RFC was put into machine readable form for entry ]
[ into the online RFC archives by Jeff Sorte 5/97 ]
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