Time-Slot Interchange
Encyclopedia
A Time Slot Interchange switch uses RAM
, memory for mapping and a counter. Like any switch, it has input and output ports.
The function of the RAM is to store the packets which are inputted to it via its input terminal. Memory for mapping stores the information.
The counter here is like a normal counter.
is stored in the memory for mapping purpose. The counter is incremented with the internal clock. Current value of counter is indicating that the data of which input port is to be forwarded.
Based on the value of the counter, it access the input port say i, then its mapping information is obtained from the memory for the mapping. RAM is accessed and the packet stored in the RAM is forwarded to the output port which is obtained through memory. Then the counter is incremented to the next value. It repeat the algorithm
for other ports.
t=2nT
which gives
n=t/2T
Now the t is the design
parameter along with n. Hence T determine n for the given t. Similarly it limits t for the given n. Here comes limitation that it cannot be used for arbitrarily large n or small t.
Random-access memory
Random access memory is a form of computer data storage. Today, it takes the form of integrated circuits that allow stored data to be accessed in any order with a worst case performance of constant time. Strictly speaking, modern types of DRAM are therefore not random access, as data is read in...
, memory for mapping and a counter. Like any switch, it has input and output ports.
The function of the RAM is to store the packets which are inputted to it via its input terminal. Memory for mapping stores the information.
The counter here is like a normal counter.
Mechanism
When packet comes to the input, it stores the packet in RAM. Its mappingMapping
In geomatics or geospatial science and technology:Mapping usually refers to map-making and often used instead of cartography.Mapping term is also sometimes used for geospatial data collection but in fact it is not mapping because a map is created from some cartographic works In geomatics or...
is stored in the memory for mapping purpose. The counter is incremented with the internal clock. Current value of counter is indicating that the data of which input port is to be forwarded.
Based on the value of the counter, it access the input port say i, then its mapping information is obtained from the memory for the mapping. RAM is accessed and the packet stored in the RAM is forwarded to the output port which is obtained through memory. Then the counter is incremented to the next value. It repeat the algorithm
Algorithm
In mathematics and computer science, an algorithm is an effective method expressed as a finite list of well-defined instructions for calculating a function. Algorithms are used for calculation, data processing, and automated reasoning...
for other ports.
Limitation
In TSI switch, twice memory access is required (one to read and one to store). Let T be the time to access the memory. Therefore, for a port 2T time will be taken to access the memory only. Let there are n input port. If t is the operation time for n lines, then it must hold the relationt=2nT
which gives
n=t/2T
Now the t is the design
Design
Design as a noun informally refers to a plan or convention for the construction of an object or a system while “to design” refers to making this plan...
parameter along with n. Hence T determine n for the given t. Similarly it limits t for the given n. Here comes limitation that it cannot be used for arbitrarily large n or small t.
See also
- Clos NetworkClos networkIn the field of telecommunications, a Clos network is a kind of multistage circuit switching network, first formalized by Charles Clos in 1953, which represents a theoretical idealization of practical multi-stage telephone switching systems. Clos networks are required when the physical circuit...
- Crossbar switchCrossbar switchIn electronics, a crossbar switch is a switch connecting multiple inputs to multiple outputs in a matrix manner....
- Nonblocking minimal spanning switchNonblocking minimal spanning switchA nonblocking minimal spanning switch is a device that can connect N inputs to N outputs in any combination. The most familiar use of switches of this type is in a telephone exchange. The term "non-blocking" means that if it is not defective, it can always make the connection...
- Banyan switchBanyan switchIn electronics, a banyan switch is a complex crossover switch used in electrical or optical switches.It is named for its resemblance to the roots of the banyan tree which cross over in complex patterns. Logical banyan switches are used in logic or signal pathways to crossover switching of signals...
- Fat treeFat treeThe fat tree network, invented by Charles E. Leiserson of MIT, is a universal network for provably efficient communication. Unlike an ordinary computer scientist's notion of a tree, which has "skinny" links all over, the links in a fat-tree become "fatter" as one moves up the tree towards the root...
- Omega networkOmega NetworkAn Omega network is a network configuration often used in parallel computing architectures. It is an indirect topology that relies on the perfect shuffle interconnection algorithm.-Connection Architecture:...