US 8,009,702 B2 · Method and arrangement for local sychronization in master-slave distributed communication systems

Abstract

A communication system which consists of several modules—operating in parallel on segments of a packet—to increase speed and handling capacity. One module acts as master, the others are slave modules controlled by control signals derived by the master module. It is important that in each module the data segment and the respective control signal of each packet are correctly synchronized, because in large systems the data paths carrying packet segments and the control signal paths may have substantially different delays. The invention provides for measurement of the propagation delay differences and for introducing a controlled delay in each slave module, so that data segments and control signals can be correctly correlated by delaying either the one or the other. Synchronization packets are transmitted besides normal data packets, for obtaining time stamps which are used to determine the delay difference.

Claims8

Dependent claims

a non-transitory program storage device readable by machine, tangibly embodying a program of instructions executable by the machine for providing local synchronization in a master-slave distributed communication network designed for processing data packets, the program instructions comprising steps of:

receiving data packets and sync packets, each data packet comprising a header containing control information, and a data payload;
partitioning the data packets into N segments for parallel processing of N different segments in different parts of the system over N different links;
sending a first segment comprising the header to a master unit;
transmitting N−1 next segments containing only data payload to slave units;
wherein N is not greater than a size of the data packet divided by a size of the header;
and splitting the sync packets into sync packet segments and injecting the sync packet segments into a same path as the data packet segments.

3 more elements

in a first slave unit for parallel processing of data segments, wherein the first slave unit is adapted to receive a data segment via a data path:
using an ingress control interface for receiving derived control information, derived sync control information, and the data segments, wherein the derived control information comprises information about control decisions made by a master unit and contains information required by the first slave unit about the control decisions made by the master unit;
and using an egress control interface for transmitting the derived control information to a next slave unit;
using a sync control detector for:
inspecting the incoming control information;
triggering load of a control time-stamp register with a sequence number provided by a sequencer if the incoming derived control information is of type sync;
locally measuring a propagation delay difference between the control and data flows by obtaining time stamps for the data path and the control path, which represent the time shift between the two paths, time shift information representing the propagation delay difference between the data path and the control path;
delaying either a data segment or derived control information, in response to the time shift information obtained by the time shift information means;
associating its segment with a corresponding derived control information counterpart by introducing a programmable delay in the data and/or control paths, such that the differences between propagation delays of the paths can be compensated for;
and forwarding the derived control information received by the first slave unit to a next slave unit until the derived control information reaches a last slave unit;
using an internal clock for continuously incrementing a counter;
and using the sequencer comprising the counter to restart counting from zero after a specific reset command;
and resetting the sequencer in response to one of:
a first receipt of a synchronization packet segment and the corresponding derived synchronization control information.

11 more elements

Dependencies are inferred from the claim text.

Method and arrangement for local sychronization in master-slave distributed communication systems

Life of this patent

Method and arrangement for local sychronization in master-slave distributed communication systems

Life of this patent

Abstract

Claims8