At Law Conferencing we realize that no matter how good our service offerings may be, they are of no use to our customers if our network is not up when you need them. Our engineering staff has worked very hard to build a system architecture utilizing the most sophisticated technology in the industry to insure reliability.
All voice traffic at Law Conferencing is supported by two local-exchange carriers and two long-distance carriers. In-house, we have more port capacity than most of our conferencing competitors.
It is of utmost importance to us that we deliver to you a secure and reliable network, and the promise that we've got all bases covered.
Law Conferencing has built a self-healing Synchronous optical network (SONET). SONET is a standard for optical telecommunications transport that was formulated by the ECSA for ANSI, which sets industry standards in the United States for telecommunications and other industries. The comprehensive SONET/synchronous digital hierarchy (SDH) standard is expected to provide the transport infrastructure for worldwide telecommunications for at least the next two or three decades.
The increased configuration flexibility and bandwidth availability of SONET provides significant advantages over the older telecommunications system. These advantages include the following:
In brief, SONET defines optical carrier (OC) levels and electrically equivalent synchronous transport signals (STSs) for the fiber-optic-based transmission hierarchy.
Synchronous versus Asynchronous
Traditionally, transmission systems have been asynchronous, with each terminal in the network running on its own clock. In digital transmission, clocking is one of the most important considerations. Clocking means using a series of repetitive pulses to keep the bit rate of data constant and to indicate where the ones and zeroes are located in a data stream.
Because these clocks are totally free-running and not synchronized, large variations occur in the clock rate and thus the signal bit rate. For example, a DS-3 signal specified at 44.736 Mbps + 20 parts per million (ppm) can produce a variation of up to 1,789 bps between one incoming DS-3 and another.
Asynchronous multiplexing uses multiple stages. Signals such as asynchronous DS-1s are multiplexed, and extra bits are added (bit-stuffing) to account for the variations of each individual stream and combined with other bits (framing bits) to form a DS-2 stream. Bit-stuffing is used again to multiplex up to DS-3. DS-3s are multiplexed up to higher rates in the same manner. At the higher asynchronous rate, they cannot be accessed without demultiplexing.
In a synchronous system such as SONET, the average frequency of all clocks in the system will be the same (synchronous) or nearly the same (plesiochronous). Every clock can be traced back to a highly stable reference supply. Thus, the STS-1 rate remains at a nominal 51.84 Mbps, allowing many synchronous STS-1 signals to be stacked together when multiplexed without any bit-stuffing. Thus, the STS-1s are easily accessed at a higher STS-N rate.
Low-speed synchronous virtual tributary (VT) signals are also simple to interleave and transport at higher rates. At low speeds, DS-1s are transported by synchronous VT-1.5 signals at a constant rate of 1.728 Mbps. Single-step multiplexing up to STS-1 requires no bit stuffing, and VTs are easily accessed.
Pointers accommodate differences in the reference source frequencies and phase wander and prevent frequency differences during synchronization failures.