Abstract: A communications system in which a first node is connected to a plurality of second nodes for controlling the operation of the second nodes. The plurality of second nodes is arranged in one or more logical interconnects, the topology of the one or more logical interconnects being distinct from the topology of the physical interconnection of the nodes. Each second node sends status messages to its logical successor node and monitors the status messages received from its logical predecessor node for determining the status thereof.

Abstract: A communications system has a plurality of islands, and a media path having resources for carrying data in a plurality of calls between first and second ones of the islands. Each of the first and second islands has a controller for managing allocation of the resources of the media path between the plurality of calls. A faulty controller is detected, and either replaced with a working replacement controller or recovered to working order. A further controller provides to the replacement or recovered controller, on replacement or recovery, information on the allocation of the resources of the media path.

Abstract: Malicious code in a code-executing device is detected by generating test data, which is substantially unsusceptible to compression without reducing its information content, and storing it as image data in memory external to the device. The test data is stored into memory of the device. A checksum calculation is performed on the test data stored in the memory of the device to generate a first checksum value. A corresponding checksum calculation is performed on the image data to generate a second checksum value. The first value is compared with the second value to determine whether or not the test data in the memory of the device has been corrupted. These steps are repeated until sufficient test data in the memory of the device is checksum tested to determine whether or not malicious code is present in the device. The malicious code is difficult to conceal itself from the checksums. Hence, it is possible to determine whether or not the device has been compromised.

Abstract: The invention provides a method of detecting malicious code in a code-executing device (10), the method characterised in that it includes the steps of: (a) generating test data which is substantially unsusceptible to compression without reducing its information content and storing it as image data (230) in memory external to the device (10); (b) loading the test data (R0 to Rm) into memory (30) of the device (10); (c) performing a checksum calculation on the test data (R0 to Rm) stored in the memory (30) of the device (10) to generate a first checksum value, performing a corresponding checksum calculation on the image data (230) to generate a second checksum value, and the comparing the first value with the second value to determine whether or not the test data in the memory of the device (30) has been corrupted; (d) repeating step (c) until sufficient test data in the memory (30) of the device (10) is checksum tested to determine whether or not malicious code is present in the device (10).

Abstract: A communications system comprising a plurality of islands, a media path comprising resources for carrying data in a plurality of calls between first and second ones of the islands in which each of the first and second islands comprises control means for managing allocation of the resources of the media path between the plurality of calls; in which the system also comprises means for detecting a faulty control means and either replacing the faulty control means with a working replacement control means or recovering the faulty control means to working order; in which the system also comprises means for providing from a further control means to the replacement or recovered control means on replacement or recovery information on the allocation of the resources of the media path.