Multiplex communications – Pathfinding or routing – Combined circuit switching and packet switching
Reexamination Certificate
1998-02-02
2001-09-04
Chin, Wellington (Department: 2664)
Multiplex communications
Pathfinding or routing
Combined circuit switching and packet switching
C370S396000
Reexamination Certificate
active
06285670
ABSTRACT:
TECHNICAL FIELD
This invention relates to telecommunications switching systems and specifically to a system in which each of the switching nodes has multiple ports for node-host communications.
BACKGROUND OF THE INVENTION
An example of the switching system to which the present invention applies is described in U.S. Pat. No. 5,544,163, Expandable Telecommunications System, the contents of which are incorporated herein by reference. The switching system comprises a plurality of programmable switching nodes and host software that exercises supervisory control over the switching nodes. The hosts are typically implemented as software applications running as a personal computer to provide various supervisory functions. The switching nodes are interconnected by an internodal switching network. A second network termed the “host network,” interconnects the switching nodes and the host computer for supervisory communications. Examples of the host supervisory applications include call setup and teardown applications and applications that perform various system monitoring and administrative functions.
In the above-referenced patent, a single system host computer communicates with the switching nodes and all messages from the switching nodes are sent to that computer. However, in some environments the host computer may be overloaded, for example, by a high frequency of call setup and teardown operations and by other functions that may be assigned by the system operator. Moreover various nodes or groups of nodes may be situated in widely separated geographic locations and communications between a single host computer and all of the switching nodes may be substantially more expensive than distribution of the host functions on a geographic basis.
To solve these problems, a prior system divides the supervisory host applications among multiple host computers. This takes care of the host computer overload problem as well as the problem with widely separated geographic locations. However, the host applications usually have different priorities, with applications that perform call setup and teardown functions requiring the highest priority in the switching nodes. The operators of the switching system may divide the supervisory host applications among multiple host computers based on the their priorities. For example, the operator may limit to one computer host applications that control and configure various switching node features or perform call setup and teardown functions. The lower priority host applications will then be placed on other computers. However, all messages received by the switching nodes have the same priority and since all hosts communicate with the switching nodes, the switching nodes in turn, process lower priority applications at the same priority level as higher priority applications. This is not a problem with a single host computer system since requests can then be sent to the switching nodes according to the priority levels of the requests.
SUMMARY OF THE INVENTION
In accordance with the invention, each switching node in the system has multiple ports for node-host communications, all ports being connected to the host network. One of the ports in each switching node is designated as a primary or master port and it is used exclusively for communications with a primary host. Incoming messages on the master port are given the highest priority on the switching node and, the primary host is therefore preferred for applications that require high priority responses in the switching nodes.
The other ports in the switching nodes are secondary ports and they are used for communications with one or more secondary hosts. Since incoming messages on the secondary ports have a lower priority, the secondary hosts involve applications that perform query operations, switch monitoring and other applications that do not require high priority response in the switching nodes. The switching nodes process incoming messages at the primary ports with a higher priority than those arriving at the secondary ports. This automatically provides higher priority handling to higher priority tasks.
Although incoming messages on the primary port have higher priorities than incoming messages on the secondary ports, the fairness algorithms often used in priority arrangements do not process higher priority tasks to the complete exclusion of lower priority tasks. A switching node may therefore be overloaded in some situations and fail to respond to higher priority applications as speedily as required. Therefore, we prefer to provide the primary host with overall control of communications with the switching nodes, including those that are transmitted to the secondary ports.
Specifically, the primary host can disable port communications at any of the switching nodes. This terminates host-node communications with the designated ports. It thus ensures that the affected node can catch up with time-critical tasks, such as call setup, that have fallen behind. The primary host can later re-enable the affected port when the switching node has sufficiently reduced its backlog of high-priority tasks.
REFERENCES:
patent: 4385206 (1983-05-01), Bradshaw et al.
patent: 4547880 (1985-10-01), De Vita et al.
patent: 4872197 (1989-10-01), Pemmaraju
patent: 5146452 (1992-09-01), Pekarske
patent: 5544163 (1996-08-01), Madonna
patent: 5579384 (1996-11-01), Seymour
patent: 5694547 (1997-12-01), Subramanian et al.
patent: 6055237 (2000-04-01), Hebert et al.
“XNL Switch and Its Control” IBM Technical Disclosure Bulletin, vol. 34, No. 8, Jan. 1, 1992, pp. 61-21, XP00030231.
Hosoya, M. et al., “Contention Solver for a superconducting packet switch” IEEE Transactions on Applied Superconductivity, vol. 7, No. 2, Jun. 1, 1997, pp. 2274-227, XP002104016.
“Arbitration for Multiprocessor Bus Switch” IBM Technical Disclosure Bulletin, vol. 36, No. 5, May 1, 1993, p. 353/354 XP000409018.
Ghai Rajat
Higgins Peter
Chin Wellington
Excel Switching Corporation
Jones Prenell
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