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Showing papers on "Fast packet switching published in 1974"


Journal ArticleDOI
TL;DR: A protocol that supports the sharing of resources that exist in different packet switching networks is presented and provides for variation in individual network packet sizes, transmission failures, sequencing, flow control, end-to-end error checking, and the creation and destruction of logical process- to-process connections.
Abstract: A protocol that supports the sharing of resources that exist in different packet switching networks is presented. The protocol provides for variation in individual network packet sizes, transmission failures, sequencing, flow control, end-to-end error checking, and the creation and destruction of logical process-to-process connections. Some implementation issues are considered, and problems such as internetwork routing, accounting, and timeouts are exposed.

802 citations



Proceedings Article
01 Jan 1974

33 citations


Journal ArticleDOI
TL;DR: It is shown that, under certain conditions, it is possible to have a packet size that minimises the total overheads and Simulations using exponentially distributed messages have been carried out.
Abstract: In packet-switched data networks, overheads are incurred primarily due to two aspects: the protocol, i.e. headers. acknowledgements etc. and blank padding of the partially used packet. In the letter, the overhead factors due to these two sources are derived under certain assumptions. Simulations using exponentially distributed messages have been carried out, and results from these are also presented. It is shown that, under certain conditions, it is possible to have a packet size that minimises the total overheads.

6 citations


Journal ArticleDOI
TL;DR: In this article, a line protection switching system, called lpss−3, is proposed to provide one standby line for protection of as many as 10 service carrying lines for the L5 repeatered line.
Abstract: A new system has been designed to provide protection switching capability for the L5 repeatered line. This line-protection switching system, called lpss−3, provides one standby line for protection of as many as 10 service carrying lines. Switching equipment is located in terminal, terminal main, and switching power-feed stations. Economic and reliability considerations allow switching spans of up to 150 miles. Either temperature pilot deviations or excessive total signal energy initiates automatic switching. Manual control of all switching functions is provided locally and via telemetry. A dedicated pcm signaling system maintains interstation switching system coordination. Identical information is transmitted in complem entary form over two adjacent L5 channels. Parity and complementary checking as well as automatic retransmission of failed codes enhances error immunity.

5 citations


20 May 1974
TL;DR: The flow control mechanism for single-packet messages was studied and the explanation for this undesirable behavior was able to be come up with.
Abstract: The transmission of digitized speech over the ARPANET represents a new dimension in the use of packet switching systems. The throughput and delay requirements for this newly emerging application area are quite different from the throughput and delay requirements for interactive use or file transfers. In particular, we need to achieve a high throughput for small messages since long messages result in long source delays to fill the large buffers. Therefore we are currently studying the throughput limits for single-packet messages. We realize that up to now little attempt was made to optimize throughput for low delay traffic. It was nevertheless surprising for us to find out that the observed throughput for single-packet messages is in many cases only about one fourth of what one would expect. In what follows we are going to explain why this happens and what could be done to correct this situation. On April 1, 1974, we sent, using the IMP message generator, single-packet messages at the highest possible rate ("RFNM-driven") from the MOFFET-IMP to the SRI-IMP. There are two three-hop paths from MOFFET to SRI, one of them involving two 230.4 kbs circuits. Since there was hardly any interfering traffic we expected an average round-trip delay of not more than 100 msec. Assuming that there are, on an average, 3 messages in transmission between MOFFET and SRI and assuming a message length of about 1000 bits this should result in a throughout of more than 30 kbs. The observed through was, however, less than 8 kbs. A repetition of the experiment showed the same result. A more detailed analysis of the collected data revealed that an average number of 3.5 messages were simultaneously in transmission between MOFFET and SRI. The throughput degradation could therefore not have been due to interfering traffic between these two sites. Also the channel utilization for all channels that were involved in the transmission was less than 40 percent. The observed mean round-trip times between MOFFET and SRI, however, were about 500 msec. Since these large round-trip times were obviously not due to physical limitations, we studied the flow control mechanism for single-packet messages and were able to come up with an explanation for this undesirable behavior. When a single-packet message arrives at the destination IMP out of order (i.e., the logically preceding message has not yet arrived there) it is not accepted by the destination IMP. It is rather …

4 citations



Journal ArticleDOI
M. McDonald1, H. Rudin
TL;DR: It is found that imposing a real priority structure can markedly influence delays when: first, the trunks are relatively heavily loaded, and second, the nodes' incoming traffic arrives over high-speed channels.
Abstract: When messages are transmitted as a series of possibly noncontiguous packets, an effective priority is introduced which favors short messages. The strength of this effect upon transmission time is investigated and compared with schemes where an additional priority scheme is imposed. It is found that imposing a real priority structure can markedly influence delays when: first, the trunks are relatively heavily loaded, and second, the nodes' incoming traffic arrives over high-speed channels.

1 citations


Journal ArticleDOI
TL;DR: A transmission control method and a call control method between packet-switched network and computers are proposed for the packet-interleaved communication on the basis of the HDLC procedure (high-level data link control procedure).
Abstract: This paper describes a study of transmission control procedure for computer-to-computer and computer-computer-to-terminal communication through a public packet-switched network. Four types of basic data link are defined over a packet travel path in the network, and the functions required for the data link are discussed. A process number and its associated control method are proposed as a method of packet-interleaved communication. By applying the result of the discussion and introducing the concept of a data link and a process number, a transmission control method and a call control method between packet-switched network and computers are proposed for the packet-interleaved communication on the basis of the HDLC procedure (high-level data link control procedure).

1 citations