TECHNICAL FIELD
The present invention relates to link fault sectionalization testing. More particularly, the present invention relates to simultaneous, multi-channel link fault sectionalization testing.
BACKGROUND ART
In signaling system 7 (SS7) telecommunications signaling networks, signal transfer point (STP) nodes terminate SS7 signaling links that carry signaling data. SS7 signaling links terminated by an STP are typically 56 kbps or 64 kbps DS-0 links. In order to transfer signaling information across long distances, many DS-0 channels may be multiplexed into a single high-speed channel, such as a DS-1 or El channel. A DS-1 channel uses a T1 carrier, which operates at 1.544 Mbps, while an E1 channel uses a carrier that operates at 2.048 Mbps. As transmission distances increase and the number of intermediate signal processing/handling components (e.g., signal regenerators, cross-connects, patch panels, etc.) increase, the potential for link failures or degradations in link quality also increases. Consequently, link fault sectionalization testing techniques have been developed to monitor and diagnose signaling link transmission problems.
Link fault sectionalization (LFS) is a technique that allows a node within a signaling network to test links, so as to determine where in the network a fault or failure is occurring. The node initiating a LFS test is able to send patterns along the path of the signaling link and place successive downstream nodes into a loopback mode of operation. The node then analyzes the patterns that come back to determine if there is a fault between the sending node and a remote node One significant limitation of current LFS test systems involves the fact an LFS controller can only control and test one channel of a TDM facility (e.g., a T1 or E1 trunk) at a time. This limitation is generally illustrated by the LFS loopback test scenario presented in . illustrates a signaling environment 100, which includes a first signal transfer point (STP) node 102 and a second STP node 104, which are connected via a TDM T1 trunk 106. TDM trunk 106 includes 24 individual DS-0 signaling channels, including a signaling channel 108. Because of the physical distance separating the STP pair, a T1 repeater element 110 is employed to perform intermediate regeneration of any signals communicated on the T1 span connecting the STP pair. As such, the repeater element 110 effectively divides the T1 span into two span segments, a first span segment 112 and a second span segment 114. In the event of a communication problem involving T1 trunk 106, STP node 102 may initiate an LFS loopback test in order to locate or isolate the T1 span segment that is responsible for the communication difficulty. More particularly, STP node 102 may select a single DS-0 signaling channel, in this case signaling channel 108, and place the signaling link channel in loopback mode. LFS diagnostics may be performed on the single channel over span segment 112. Once the test for the first channel is completed, the test must be repeated for each individual channel until the fault is isolated. Thus, current LFS test systems require that tests for individual channels be run serially.
In other words, an LFS controller function associated with STP node 102 is dedicated to processing a single channel of the TDM signaling facility for the duration of an LFS test. Consequently, each time that a different signaling channel or link needs to be tested, an operator must manually reconfigure the LFS controller to test the desired TDM channel. This operating limitation becomes significantly burdensome when it is considered that, as part of link installation, network operators typically run LFS tests for up to 24 consecutive hours on a single, specific link to assess the bit error rate (BER) characteristics of that link. Consequently, per link LFS testing on an entire communication trunk (e.g., a T1 trunk) could take weeks. Furthermore, network elements are becoming increasingly capable of handling higher link density communication interfaces, which will only serve to exacerbate this problem.
Accordingly, there exists a long-felt need for improved methods and systems for performing LFS testing in a communications network.
DISCLOSURE OF THE INVENTION
According to one aspect, the present invention includes a network routing node, such as a signaling system 7 (SS7) signal transfer point (STP) or signaling gateway (SG), that terminates multiple signaling communication links and simultaneously performs link fault sectionalization (LFS) testing on some or all of the links. An STP node may include a communications link interface module that terminates a time division multiplexed (TDM) T1 trunk, where the trunk includes 24 DS-0 signaling link channels. To efficiently facilitate LFS testing of the trunk, a single LFS state machine may service some or all of the signaling channels associated with the trunk. The LFS state machine may simultaneously perform LFS testing on some or all of the 24 associated DS-0 channels by periodically storing, retrieving and processing LFS state information related to each signaling channel. As such, a single LFS state machine may be shared or multi-tasked among multiple channels of a TDM trunk.
In an extension of the technique described above, signaling channels associated with multiple TDM trunks may be serviced by a single LFS state machine, thereby minimizing the amount of LFS-related resources required to support simultaneous LFS testing of multiple TDM facilities.
The LFS state machine may be implemented using a microprocessor or a programmable logic component, such as a field programmable gate array (FPGA), which may be located on the link interface module.
As used herein, the term “link fault sectionalization test” is intended to refer to generically to any suitable loopback-based test of a TDM channel associated with a signaling link in which testing for each channel is implemented using a state machine. One example of such a test is the LFS test used for testing TDM-based SS7 signaling links. However, as will be described in detail below, the multi-channel LFS test methods and systems described herein may be used to test other types of TDM channels, including bearer channels and non-SS7 signaling channels.
Accordingly, it is an object of the present invention to provide methods and systems for simultaneously testing multiple communications links.
It is another object of the present invention to provide a link interface module for simultaneously testing multiple communication channels.
It is yet another object of the present invention to provide an LFS state machine for simultaneously testing multiple communication channels.
It is yet another object of the present invention to provide methods and systems for reducing the time required to perform LFS bit error rate (BER) testing on multiple signaling links.
Some of the objects of the invention having been stated hereinabove, other objects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.
About IP.com
