Multiplex communications – Fault recovery – Bypass an inoperative station
Reexamination Certificate
1998-03-18
2002-04-23
Vincent, David R. (Department: 2661)
Multiplex communications
Fault recovery
Bypass an inoperative station
C370S406000
Reexamination Certificate
active
06377542
ABSTRACT:
BACKGROUND OF THE INVENTION
Field of the Invention
Synchronous Digital Hierarchy (SDH) equipment is the latest generation of equipment that is used to provide high bandwidth communications capabilities for use between telephone exchanges and in other areas where high quality telecomms is required (broadcast video distribution, etc). Embedded within the traffic ‘traffic’ carrying capability of the equipment are data communications channels (DCCs). These channels constitute a datacomms network that uses OSI protocols.
Each piece of equipment constitutes a routeing node in the datacomms network formed by the data channels, and can operate any one of a number of different routeing methods. The present invention is concerned with the interworking of two of the possible routeing methods.
The two routeing methods that will commonly occur in SDH networks are IS—IS (ISO 10589) and quasi-static routeing (where alternate routes may be chosen on link failure). Where this occurs, routeing loops, causing loss of communications can be caused. The present invention detects the formation of a routeing loop and changes the behavior of the IS—IS node accordingly.
The IS—IS routeing protocol is one of a set of ‘link state’ dynamic routeing protocols. These protocols automatically distribute routeing information round the datacomms network, allowing nodes to learn the required routeing information from the actual network. This provides the ability to automatically reconfigure, allowing routeing round network faults, in case of network link failure.
The IS—IS routeing protocol has two routeing levels, Level-
1
and Level-
2
. See
FIG. 2
(from ISO 10589) for the use of these levels and the general environment of this protocol and the topologies and systems supported by Intradomain Routeing.
The present invention is also applicable to other datacomms scenarios, where a dynamic routeing protocol is interworked with static routeing, or a different dynamic protocol (e.g. OSPF and static routes, etc).
SUMMARY OF INVENTION
According to the present invention there is provided a Synchronous Digital Hierarchy (SDH) based communications network comprising a plurality of Intermediate Systems (IS), the ISs being divided between at least one IS—IS Area and at least one non-IS—IS Area, an IS—IS Area being an area with which a routeing protocol forming part of the Network Layer (Layer
3
) of the Open Systems Interconnection including routeing (OIS), is provided for routeing messages between areas, including routeing means, whereby where a message is routed from an IS—IS Area to a destination IS within a non-IS—IS Area and the connection to the destination IS is broken, and as a result a message is returned from the non-IS—IS Area to the originating IS—IS Area connection to the destination IS is made by a second choice connection.
There is further provided a method for use in Synchronous Digital Hierarchy (SDH) based communications network comprising a plurality of Intermediate Systems (IS), the IS being divided between at least one IS—IS Area and at least one non-IS—IS Area, wherein when a message is returned from the non-IS—IS Area to the originating IS—IS Area a second choice connection to the destination IS is made.
REFERENCES:
patent: 5262906 (1993-11-01), Mazzola
patent: 5307353 (1994-04-01), Yamashita et al.
patent: 5430727 (1995-07-01), Callon
patent: 5440540 (1995-08-01), Kremer
patent: 5497368 (1996-03-01), Reijnierse et al.
patent: 5557745 (1996-09-01), Perlman et al.
patent: 5717687 (1998-02-01), Minot et al.
patent: 5719861 (1998-02-01), Okanoue
patent: 5793765 (1998-08-01), Boer et al.
patent: 5856974 (1999-01-01), Gervais et al.
Kirschstein et al.
Marconi Communications Limited
Phunkulh Bob A.
Vincent David R.
LandOfFree
Rap alternate routeing for ISO 10589 does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Rap alternate routeing for ISO 10589, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Rap alternate routeing for ISO 10589 will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2841496