Rotator switch data path structures

Details Rotator switch data path structures Rotator switch data path structures

1998-04-09

2001-10-23

Chin, Wellington (Department: 2664)

Multiplex communications

Pathfinding or routing

Combined circuit switching and packet switching

C370S412000, C370S417000, C370S418000, C340S002200, C340S002260, C340S002280

Reexamination Certificate

active

06307852

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to rotator switches and is particularly concerned with data path structures.
BACKGROUND TO THE INVENTION
The rotator is a form of buffered space switch in which connections between a set of sources and destinations are made though a set of tandems each containing buffer memory, the tandems are connected in rotation to each source, and in rotation to each destination. In the most basic form of the rotator, there are equal numbers of source, destination and tandem nodes, and rotation of connections is achieved by means of a space switch between the tandem and source and between the tandem and destination nodes. The bandwidth of each interconnecting link used to form a commutated paths through the space switch, is made equal to or with dilation made greater than the input rate of each source or equally the output rate of any destination.
In the rotator described in prior art which will be referred to as the original rotator, during each phase of the cycle, K information units (IU)-are transferred from the tandem to each destination, and K IUs are transferred from each source to each tandem. The basis of operation ensured by the scheduling or collision avoidance matching process is that at any time the tandem can be assigned a maximum of only K IUs for any given destination. For the purposes of this document and without loss of generality of the enhancements, the value of K will be set to one information unit for both the original rotator and the enhanced rotator. The number of sources, destinations, and tandems are represented by s, d, and t, respectively. Thus in general for K=1 for the original rotator, the tandem will have s=d IU storage locations, which are read out in the sequence shown in the table.
Source 0
Source 1
Source 2
Source 3
connects to
connects to
connects to
connects to
Cycle
Phase
tandem #
tandem #
tandem #
tandem #
0
0
0
3
2
1
0
1
1
0
3
2
0
2
2
1
0
3
0
3
3
2
1
0
1
0
0
3
2
1
1
1
1
0
3
2
1
2
2
1
0
3
1
3
3
2
1
0
Since all tandems visit all destinations, in the simplest matching process, any source may place an IU on any tandem not already having an IU for that destination. In implementation this means that the address in the RAM to which an IU placed is equivalent to the destination identity and this may be passed to tandem as a parameter with, or in advance of the IU requiring a label of length log
2
(d) bits. The addressing of read out for transfer to the destination simply follow the connection sequence and may employ a simple modulo d counter incremented at every phase of the rotation.
If one tandem is considered in isolation it can be seen that in s=d=t phases it provides each destination with one IU and that this IU can come from any one of the s sources. For any given rotation, sources are mutually exclusive (i.e., two IUs cannot come from the same source and go to different destinations in the simple original rotator). Thus, viewed independently, each tandem provides connectivity directly equivalent to that of a space switch except that the connection between the sources and destinations is spread out (sheared) in time over the period of one rotation (*note 1). Given there are s tandems and s phases per rotation, instead of being equivalent to one re-configuration of a an s by s space switch per rotation, the total effect is equivalent to one reconfiguration of an s by s space switch per phase, one phase step being the time it takes to transfer one IU.
*Note 1: There is one other constraint in terms of the original rotator, this is that each decision on allocation to a tandem is dependent on the previous
3
allocation decisions, a constraint in the form of a moving window.
SUMMARY OF INVENTION
An object of the present invention is to provide an improved rotator switch.
In accordance with an aspect of the present invention there is provided a rotator switch having a rotation cycle and comprising a plurality of source nodes, each source node having an output, a first commutator, a plurality of intermediate nodes, each said intermediate node including two random access memories, the first one for being written to, the second for being read from during each rotation cycle, means for swapping said first and second memories at a same point in the rotation cycle in time or alternatively relative to a particular source or destination, such that selecting unoccupied memory locations is independent of allocations made in the previous cycle of rotation, a second commutator and a plurality of destination nodes. whereby the output from the memories are written via the second commutator and the plurality of destination nodes.
In accordance with another aspect of the present invention there is provided a rotator switch having a multiplexing group of K1 sources onto one tandem rotator switch comprising: a plurality of source nodes, each source node having an output multiplexed with the output of another source node to provide a multiplexed output; a first commutator connected to the multiplexed outputs; a plurality of intermediate nodes connected to the first commutator- a second commutator connected to the intermediate nodes and having a plurality of multiplexed outputs; and a plurality of destination nodes, each destination node having an input demultiplexed with the input of another destination node to from the plurality of multiplexed output, whereby each tandem becomes a compound tandem being connected to K1 source nodes at any phase of the rotation.
An advantage of this aspect of the present invention is that the duration of rotation and the total tandem memory-Tequirement is reduced by a factor of K
1
times compared with that of the prior art rotator employing equivalent numbers of sources, tandems and destination nodes. This aspect is differentiated from a double rate source, double rate tandem-and double rate destination with block size K in the prior art by the process of retaining scheduling for each of the K
1
multiplexed sources and destinations as singular independent sources and destinations thereby limiting source and destination memory bandwidth and ensuring equality in distribution of assigned switching bandwidth.
In accordance with another aspect of the present invention there is provided a rotator switch comprising: a plurality of source nodes being divided into a plurality of (K
2
) sub-groups, each source node of a sub-group having an output to a specific-commutator, said rotator switch comprising a first plurality of switches, a plurality of intermediate nodes, each intermediate node connected to each of said first plurality of switches of the first commutator, a second commutator including a second plurality of switches, each of said second plurality of switches connected to each of the plurality intermediate nodes, up to and including a K
2
th commutator including a K
2
th plurality of switches each of said K
2
th plurality of switches connected to each of the plurality intermediate nodes and a plurality of destination nodes, each destination node having an input connected to one of the K
2
th plurality of switches forming the inverse of the connectivity of the source to intermediate node connectivity,whereby the compound tandem is connected via K
2
commutators of relative size 11K
2
, thus reducing the dimensions of the first and second commutators and enabling them to be associated with each sub-group of sources and destinations hence allowing more efficient partitioning.
In accordance with a further aspect of the present invention there is provided a rotator switch comprising: a plurality of source nodes, each source node. having an output, a first rotator plane including a first commutator including a first plurality of switches each of said first plurality of switches connected to at least some of the source node outputs, a first plurality of intermediate nodes each intermediate node connected to each of said first plurality of switches of the first commutator, a second commutator including a second plurality of switches each of said second

Affiliated with

Also associated with

Rating

Rotator switch data path structures does not yet have a rating. At this time, there are no reviews or comments for this patent.

If you have personal experience with Rotator switch data path structures, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rotator switch data path structures will most certainly appreciate the feedback.

Rate now

Comments { 0 }

Profile ID: LFUS-PAI-O-2595504