On the addressing problem for loop switching
On the addressing problem for loop switching
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DOI：
10.1002/j.1538-7305.1971.tb02618.x
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发表时间：
1971-10
影响因子：
--
通讯作者：
R. Graham;H. Pollak
中科院分区：
文献类型：
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作者：
R. Graham;H. Pollak
用于执行贝尔系统的交换功能的方法是在基本假设下开发的，即完成呼叫的保持时间比建立呼叫所需的时间长。在考虑与计算机之间的某些形式的通信时，出现了这样一种可能性，即以其目的地为头部的消息可能在通信网络中穿行，而无需等待在开始其旅程之前物理实现完整的专用路径。J.R.皮尔斯和可能被称为“循环切换”。我们想象用户，也许最好被认为是计算机终端或其他数据生成设备，单向循环。这些“本地”环路通过各种交换点彼此连接以及连接到其它“区域”环路，其它“区域”环路又彼此连接以及连接到“国家”环路。如果来自一个环路的消息的目的地是另一个环路上的用户，则该消息绕着始发环路前进到合适的交换点，在该交换点处，该消息可以选择进入不同的环路，该过程继续，直到该消息到达其目的地。问题自然出现了，消息如何知道要遵循哪个循环序列。希望每个连接处的设备能够对目的地寻址环路应用简单的测试，该测试具有几个吸引人的特征：（i）它允许消息在到达其目的地时使用极其简单的路由选择策略。(ii)通过使用此策略，消息将始终在同一区域中的任何两个局部循环之间采用最短的可能路径。{iii)寻址的方法适用于任何回路的集合，不管它们的互连多么复杂。我们提出的寻址方案将主要应用于相互连接可能会有很大不同的本地环路。如果像J. R。Pierce 1有可能实现既紧凑又相当有效的寻址。
The methods used to perform the switching functions of the Bell System have been developed under the fundamental assumption that the holding time of the completed call is long compared to the time needed to set up the call. In considering certain forms of communication with and among computers the possibility arises that a message, with its destination at its head might thread its way through a communication network without awaiting the physical realization of a complete dedicated path before beginning on its journey. One such scheme has been proposed by J. R. Pierce and may be called “loop switching.” We imagine subscribers, perhaps best thought of as computer terminals or other data generating devices, on one-way loops. These “local” loops are connected by various switching points to one another as well as to other “regional” loops which are in turn connected to one another as well as to a “national” loop. If a message from one loop is destined for a subscriber on another loop it proceeds around the originating loop to a suitable switching point where it may choose to enter a different loop, this process continuing until the message reaches its destination. The question naturally comes up, how the message is to know which sequence of loops to follow. It would be desirable for the equipment at each junction to be able to apply a simple test to the destination addressing the loops which has several attractive features: (i) It permits an extremely simple routing strategy to be used by the messages in reaching their destmations. (ii) By using this strategy, a message will always take the shortest possible path between any two local loops in the same region. {iii) The method of addressing applies to any collection of loops, no matter hoio complex their interconnections. The addressing scheme we propose will be applied primarily to local loops where the mutual interconnections may be quite varied. If a certain amount of hierarchical structure is introduced into the regional and national loop structure, as suggested by J. R. Pierce1 it is possible to achieve addressings which are both compact and quite efficient.