As per Relevance of the word expedited, we have this rfc below:
Network Working Group Y.
Request For Comments: 1859 Intel Corp
Category: Informational October 1995
ISO Transport Class 2 Non-use of Explicit Flow Control over
RFC1006
Status of this
This memo provides information for the Internet community. This
does not specify an Internet standard of any kind. Distribution
this memo is unlimited
Table of
1. Introduction - General recommendations.......................2
2. The protocol.................................................3
2.1 TCP service as a Network Service - The Primitives...........3
2.2 Connection Establishment....................................4
2.3 Data Transfer...............................................5
2.4 Connection Release..........................................6
3. Packet Format................................................6
4. DIGITAL DECnet over TCP/IP...................................8
Acknowledgements................................................9
References......................................................9
Author's Address................................................9
1. Introduction - General
This document is an extension to STD35, RFC1006, a standard for
Internet community. The document does not duplicate the
definitions contained in RFC1006 and in International Standard
8073. It supplements that information with the description of how
implement ISO Transport Class 2 Non-use of Explicit Flow Control
top of TCP
The document should be used in conjunction with the RFC1006 and
8073.
The RFC1006 standard defines how to implement ISO 8073
Class 0 on top of TCP. This memo defines how to implement ISO 8073
Transport Class 2 Non-use of Explicit Flow Control on top of TCP
Like ISO Transport Class 0, Class 2 Non-use of Explicit Flow
provides basic connection with minimal overhead
A Transport protocol class is selected for a particular
connection based upon the characteristics of the lower layers and
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RFC 1859 ISO Transport and Flow Control October 1995
requirements of the upper layer. Use of class 2 Non-use of
Flow Control is suitable when the use of separate virtual
channels for normal and expedited Data are desirable or when
explicit disconnection of the Transport connection is desirable
Hosts which choose to implement this extension are expected to
on the well-known TCP port number 399.
It is recommended that the well-known RFC1006 TCP port 102 not
used. This recommendation is done to minimise impact to an
RFC1006 implementation
The memo also describes the use of this extension within the
Network Architecture (DNA).
2. The
The protocol specified by this memo is fundamentally equivalent
the protocol ISO 8073 Transport Class 2 Non-use of Explicit
Control, with the following extensions
- Expedited Data service is supported
- Splitting and Recombining may be used for Expedited
transmission
- The Network Service used is provided by TCP
The ISO 8073 Transport protocol Class 2 allows Multiplexing. It
recommended that this capability not be use for performance reasons
The ISO 8073 Transport protocol exchanges information between
in discrete units of information called transport protocol data
(TPDUs). The protocol defined in this memo encapsulates these
in discrete units called TPKTs. The structure of these TPKTs
their relationship to TPDUs are discussed in the next sections
2.1 TCP service as a Network Service - The
The mapping between the TCP service primitives and the
primitives expected by ISO 8073 Transport when operation
Connection-oriented network service is straightforward
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RFC 1859 ISO Transport and Flow Control October 1995
Note: The following description of the mapping is a repeat from
RFC1006 standard
network service
--------------- ---
CONNECTION
N-CONNECT.REQUEST open
N-CONNECT.INDICATION listen (PASSIVE open)
N-CONNECT.RESPONSE listen
N-CONNECT.CONFIRMATION open (ACTIVE open)
DATA
N-DATA.REQUEST send
N-DATA.INDICATION data ready followed by read
CONNECTION
N-DISCONNECT.REQUEST
N-DISCONNECT.INDICATION connection closes or
Mapping parameters between the TCP service and the network service
also straightforward
network service
--------------- ---
CONNECTION
Called address server's IP address (4 octets
Calling address client's IP address (4 octets
all others
DATA
NS-user data (NSDU)
CONNECTION
all parameters
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RFC 1859 ISO Transport and Flow Control October 1995
2.2 Connection
The principles used in connection establishment are based upon
described in ISO 8073, with the following extensions
- Connection Request and Connection Confirmation TPDUs may
the use of Expedited Data transfer using the negotiation
specified in ISO 8073.
- Connection Request and Connection Confirmation TPDUs must
negotiate the Use of Explicit Flow Control
To perform an N-CONNECT.REQUEST action, the TS-peer performs
active open to the desired IP address using the well know TCP
399. When the TCP signals either success or failure, this results
an N-CONNECT.INDICATION action
To await an N-CONNECT.INDICATION event, a server listens on the
know TCP port 399. When a client successfully connects to this port
the event occurs and an implicit N-CONNECT.RESPONSE action
performed
2.3 Data
The elements of procedure used during transfer are based upon
presented in ISO 8073, with the two following extensions
- Expedited Data may be supported (if negotiated during
establishment).
In Non-Use of Explicit Flow Control Expedited Data requires
Expedited Data Acknowledgement
- Splitting and Recombining may be used for Expedited
transmission
The procedure of Splitting and Recombining allows a
connection to make use of multiple TCP connections
TCP connections created for Splitting purposes should also
the primitives described in 2.1.
It is recommended to only create a second TCP connection
Expedited Data when transmission of Expedited Data is requested
Expedited Data must only be sent over an outgoing TCP connection
This second TCP connection must not be shared among
connections and must remain established until the
connection is terminated, at which time it must be closed
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RFC 1859 ISO Transport and Flow Control October 1995
Implementors note: The procedure of Splitting and Recombining
Expedited Data transmission guaranties that a congested Normal
TCP connection cannot block an Expedited Data TCP connection. It
ensures independence of the Normal Data TCP connection from
Expedited Data TCP connection
To perform an N-DATA.REQUEST action, the TS-peer constructs
desired TPKT and uses the TCP send data primitive
To trigger an N-DATA.INDICATION action, the TCP indicates that
is ready and a TPKT is read using the TCP read data primitive
2.4 Connection
The elements of procedure used during a connection release
identical to those presented in ISO 8073.
A connection can be terminated by the user in one of two ways
- Abort Disconnect specifies that all messages at the source are
required to be sent to the destination before the connection
disconnected
- Synchronous Disconnect specifies that all messages at the
must be sent to the destination, and that all messages at
destination must be delivered, before the connection
disconnected
Disconnect Request and Disconnect Confirmation TPDUs are exchanged
both cases. The Disconnect Request TPDU carries a code indicating
reason for the disconnection
In the case of a Synchronous Disconnect the Disconnect Request
code is normal (80 hex). For an Abort Disconnect the
Request reason code is normal with additional information
value set to (c0 hex).
Upon receipt of a Disconnect Confirmation TPDU a N-DISCONNECT.
action is performed to close the TCP connection
If the TCP connection fails for some other reason, this generates
N-DISCONNECT.INDICATION event
3. Packet
A fundamental difference between TCP and the network service
by ISO transport is that TCP manages a continuous stream of octets
with no explicit boundaries
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RFC 1859 ISO Transport and Flow Control October 1995
The protocol described in RFC1006 uses a simple packetization
in order to delimit TPDUs. Each packet, termed a TPKT, consists
two parts: a packet-header and a TPDU
We use the same scheme described in RFC1006 for this extension
There is no need to change the version number. The ISO transport
sufficiently describes the transport protocol class being used
The format of the packet-header described below is a repeat
RFC1006.
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| vrsn | reserved | packet length |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
where
vrsn 8
This field is always 3 for the version of the
described in this memo
packet length 16 bits (min=7, max=65535)
The packet length is the length of the entire packet
octets, including packet-header
The format of the ISO transport TPDU is defined in ISO 8073.
4. DIGITAL DECnet over TCP/
DECnet over TCP/IP is implemented using the DECnet Session
layer over this RFC1006 extension protocol
The informational RFC defined in this document provides the
Service functionality required by DECnet Applications while
over TCP/IP
The next paragraph is a brief summary of the role of the
Session Control Layer. For further details, refer to the DIGITAL
Session Control Layer Specification
The DECnet Session Control Layer makes a Transport Service
to End Users of a network. This layer is concerned with system
dependent functions related to creating, maintaining, and
Transport Connections. Separate virtual data channels, known
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RFC 1859 ISO Transport and Flow Control October 1995
"Normal" and "Expedited", are provided to End Users.
Session Control must be guaranteed independence of these channels
the Transport Layer. Expedited Data transmission cannot be blocked
a congested normal data channel. DECnet Session Control requires
all data in transit be delivered before initiating the release of
Transport Connection
DECnet, DNA, and the DIGITAL logo are trademarks of Digital
Corporation
Bill Duane, Jim Bound, David Sullivan, Mike Dyer, Matt Thomas,
Harrington and many other members of the DECnet engineering team
[ISO8072] ISO. "International Standard 8072.
Processing Systems -- Open Systems Interconnection
Transport Service Definition."
[ISO8073] ISO. "International Standard 8073.
Processing Systems -- Open Systems Interconnection
Transport Protocol Specification."
[ISO8327] ISO. "International Standard 8327.
Processing Systems -- Open Systems Interconnection
Session Protocol Specification."
[RFC791] Postel, J., "Internet Protocol - DARPA Internet
Protocol Specification", STD 5, RFC 791,
USC/Information Sciences Institute, September 1981.
[RFC793] Postel, J., "Transmission Control Protocol -
Internet Program Protocol Specification", STD 7,
793, USC/Information Sciences Institute, September 1981.
[RFC1006] Rose, M., and D. Cass, "ISO Transport Services on Top
the TCP - Version: 3", STD 35, RFC 1006,
Research and Technology Center, May 1987.
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RFC 1859 ISO Transport and Flow Control October 1995
Security
Security issues are not discussed in this memo
Author's
Yanick
End Systems
Digital Equipment
Centre Technique (Europe
B.P. 027
950 Routes des
06901 Sophia antipolis,
Phone: +33 92-95-62-85
Fax: +33 92-95-62-32
EMail: pouffary@taec.enet.dec.
Pouffary Informational [Page 8]
if you see any problems within the linking, don't worry be happy,
this is version 0.1 of the Relevance System and you gotta expect some crappy subroutines sometimes,
just be content we did not write this in Java, which would have made this "bigger and better" HAHAHHA.
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