Channel Bank Operation

Problem
As your company has expanded, more and more services are being purchased from the local telephone company. With telephone lines and data connections expanding, the time has come to consider connecting to the PSN with a digital T1 transmission line. How can you take your present telephone company connections and switch them over to one high quality T1 connection?

Solution
Coastcom's D/I Mux III in channel bank mode connects directly to the PSN with one T1 transmission trunk. D/I Mux III offers a great variety of channel cards which offer circuits similar to those supplied by the local telephone company. D/I Mux III also creates options to use special services from the PSN which may not be available from the local telephone company.

How Does It Work?
A D/I Mux III in channel bank mode allows one T1 to be terminated. The T1 is synchronized to the PSN network by recovering the clock it receives from the PSN T1. In a private network, where one channel bank communicates directly to another, one of the channel banks would be the source of timing and the other would synchronize to the received T1 clock.

Figure s1. Channel Bank Operation

What Actually Occurs?
The law firm of Lee M. Haung is doing brisk business and has added two new law associates to its staff. Each new employee requires a telephone and modem line.

The telephone requirements are presently handled by a key system which allows an operator to switch calls from three 2-Wire trunks supplied by the local telephone company. Each modem now requires a separate connection and installation.

With the D/I Mux III, all communications connections are made at one point. The customer easily adds circuits as required. The PSN only needs to change software programming to accommodate the new circuits.

How Do You Set It Up?
FXS channel cards in FXS mode can supply the telephone and modem requirements. The three 2-Wire trunks are connected to the FXS circuits. Common 2-Wire modems also connect to FXS circuits. Coastcom also has 4-Wire channel cards to supply dedicated 4-Wire modem connections.

What Do You Order?
One D/I Mux III multiplexer is required. A quad (four circuit) or a dual (two circuit) FXS channel card is required to supply basic telephone service. A ringing generator is also required to supply ringing to the lines.

Drop and Insert Backbone Network

Solution
Coastcom D/I Mux IIIs, in drop and insert mode, can extend the T1 received from the corporate center to the various buildings. A drop and insert backbone network provides a single connection to the public network, creates a cost savings, and insures the high quality of digital T1 service.

How Does It Work?
A D/I Mux III backbone network consists of two D/I Mux IIIs in channel bank mode communicating with each other. Between the two D/I Mux IIIs, in channel bank mode, are D/I Mux IIIs in drop and insert mode.

A D/I Mux III in drop and insert mode allows information to be dropped (received) and inserted (transmitted) along a T1 transmission line. If the information is not required at the drop and insert site, then it can pass through the system to the next location.

When information passes through the D/I Mux III, it is received on the T1-1 port and passes through the system and out of the T1-2 port. Information from the T1-2 port passes through to the T1-1 port. Information that passes through a D/I Mux III in drop and insert mode remains digital and maintains high quality.

Figure s2. Drop and Insert Backbone Network

What Actually Occurs?
Big Tractor Manufacturing has installed a D/I Mux III in each of its buildings to create a drop and insert backbone network. T1 transmission over inexpensive twisted pair cable reaches one mile, which allows easy connection to all the buildings at the site. A microwave radio carries the T1 to and from the corporate center.

The corporate center PBX switches calls from the PSN and D/I Mux III. The PBX connects to the PSN and D/I Mux III with common 2-Wire trunks. The T1 from the corporate center is carried over a microwave link to the manufacturing site.

From the PSN a call comes in for the frame manufacturing building. The call rings the PBX which rings an FXO channel card in the D/I Mux III. The FXO places the call on a T1 transmission channel which goes to the D/I Mux III at the frame manufacturing building. An FXS channel card at the frame manufacturing building then delivers the call to a standard telephone. The call informs the frame manufacturing supervisor of a delivery.

The frame manufacturing supervisor calls and informs the gate guard of the delivery. The call is made over the same FX circuit but directed by the PBX to the guard house over a different FXO channel card. The supervisor then instructs the gate guard to hold the truck until the shipping list is compared with the purchase requisition.

When the truck arrives, the gate guard faxes the shipping list to the purchasing department at the corporate center. Once again the information is carried over an FX circuit, but this time it is delivered by the PBX to the purchasing department at the corporate center. When a discrepancy is discovered, the purchasing department calls the supplier through the PBX, which makes the connection to the PSN.

D/I Mux IIIs, in drop and insert mode, allow several remote sites to use the same PBX. Instead of having the LEC supply a telephone to every building, the remote telephones take advantage of the PBX's switching function and PSN connection.

How Do You Set It Up?
The FXO channel cards at the corporate site would be operated in FXO loop start mode. FXS channel cards connected directly to telephones require loop start operation.

What Do You Order?
A D/I Mux III is required at each building and at the corporate center. FXO circuits are installed at the corporate center. FXS circuits plus ringing generators are required at each building site.

Dual Channel Bank Operation

Solution
Operating D/I Mux III in dual channel bank mode doubles the capacity of the transmission system by allowing another T1 to be accessed from the PSN. Dual channel bank mode does not require a new shelf or system hardware. Only channel cards would be required for the new circuits. Dual channel bank mode is a selection in the D/I Mux III system software.

How Does It Work?
A D/I Mux III in dual channel bank mode allows two T1s to be terminated. The two T1s are synchronized. In dual channel bank mode the timing comes from one of the T1 lines or is supplied to both T1 lines from the D/I Mux III's internal clock.

Ports T1-1 and T1-2 on the D/I Mux III connect to the T1 lines. The T1 lines operate like two separate channel banks. Information does not pass through the system from one T1 line to the other T1 line as it does in drop and insert operation.

Figure s3. Dual Channel Bank Operation

What Actually Occurs?
The Motivational Center sells books, audio tapes, and presents seminars on motivation and human potential. Sales at the Motivational Center have increased at an exponential rate. To meet the communications needs another T1 transmission line is purchased from the PSN.

To work with the latest print technology, a Switched 56 data circuit will be added so electronic files can be downloaded to the printer company. A high quality audio link is installed so material recorded at the Golden Pelican recording studios can be reviewed on a daily basis. For better customer service, toll free 800 lines are installed. Customer's access the PSN and your 800 service switch (PBX 800) when they dial your 800 number over a standard telephone.

How Do You Set It Up?
FXS channel cards are setup in Megacom 800 mode to supply toll free 800 customer service lines. The 800 service requires FXS hardware at the corporate center. Any standard telephone can access the 800 number.

An OCUDP channel card supplies the network interface for the Switched 56 service. A Switched 56 data circuit is required at the printer's location. This is not a dedicated service; you will only pay for service time used during the call to the printer.

A receive DPC is required at the corporate center and a transmit DPC is required at the studio end.

What Do You Order?
A D/I Mux III is required at the Golden Pelican studio and at the corporate center. Quad or dual 2-Wire FXS channel cards will supply the 800 service lines at the corporate center. A ringing generator would also be required for the 800 lines.

An OCUDP is installed with a Switched 56 CSU/DSU at the corporate center. The printer's location would need a Switched 56 connection and a switched 56 CSU/DSU.

A transmit DPC is required at the Golden Pelican studio and a receive DPC is required at the corporate center.

TWIN T1M / LAN to WAN Connections

Solution
Coastcom's TWIN T1M allows several LANs to be connected over a high speed data link. The TWIN T1M is ideal for linking LANS, data concentrators, and compressed video.

How Does It Work?
TWIN T1M would be used for connecting to three or four T1s. D/I Mux III or the T1M CSU/DSU could be used if connecting to only one or two T1s. With high-speed SDCUs installed in the TWIN T1M, connection to several high speed LAN bridges is made simple.

Figure s4. TWIN T1M LAN Connections

What Actually Occurs?
The Overall Insurance Company has seen a lot of growth with its quick response to changing client requirements. New approaches to operating the business are brought up on a daily basis. In order to avoid lawsuits, Overall Insurance Company must provide the same services to all their clients throughout the country. A WAN allows the whole company to communicate instantly and to make decisions in a timely manner.

Agent Tom Wright has a client that wants to insure his home, business, and helicopter with Overall Insurance if the coverage and price are agreeable. Tom has done calculations on the risk involved with the various properties and has come up with a figure for the three items.

Tom sends the information on the LAN to the underwriters group for approval. The underwriter's database does not show any similar type situations, so the approval must come from a senior underwriter with executive approval. The files are easily transferred over the LAN to both parties and approved. The case is then entered into the underwriter's database for future reference.

How Do You Set It Up?
Install four SDCUs in a TWIN T1M at the corporate center. Each SDCU operates at its maximum data rate of either 1.536 Mbps (with B8ZS T1 line coding) or 1.344 Mbps (with standard T1 line coding) to fully utilize each of the four T1s. Each SDCU is routed on a different T1 path. Both of the internal multiplexers within the TWIN T1M are set to operate in dual channel bank mode to supply the four T1 lines.

The network file server located at the corporate center is where the shared files are kept and traded. A T1M CSU/DSU at each of the other offices connects the LAN to the corporate center LAN, easily creating a WAN.

What Do You Order?
Dedicated leased or private T1 lines are required to transport the information whenever the LANs request. One TWIN T1M with four SDCUs is required at the corporate center. Four T1M CSU/DSUs with one SDCU installed in each is required at the other offices.

FDLP / High Quality T1 transmission

Solution
The D/I Mux III can generate a minor alarm when a frame error rate or CRC error rate threshold is passed. When the D/I Mux III is in ESF mode, the FDLP option can log the transmission quality into an error history report. You can deploy a backup T1 transmission system when the primary system fails or experiences a high error rate.

How Does It Work?
The LIUs detect T1 transmission errors and report them to the CCU and FDLP. The CCU will send a minor alarm to the D/I Mux III control system when a user selectable error threshold is passed. The FDLP registers the errors in the form of errored seconds and failed seconds, then logs the errors into 15 minute, hour, and day reports. The FDLP can also be configured to print out error reports.

Figure s5. High Quality T1 Transmission

What Actually Occurs?
When a big snow storm hits, the T1 transmission paths between the microwave towers is degraded, the error rate on the primary path then passes the threshold of acceptable errors. A minor alarm is reported to the D/I Mux III control terminal, computer, or NCC. The network manager, seeing that the storm is predicted to last, decides to switch over to the backup T1 transmission line.

How Do You Set It Up?
Any intelligent Coastcom multiplexer (the D/I Mux III, the T1M CSU/DSU, or the TWIN T1M) will perform the error rate alarm function. To observe the error rate threshold, enter the Set ERT Alarm screen using the SB command from the system control menu. Select an error rate threshold and enable the alarm.

If using ESF and an FDLP is installed, the Performance Monitor screen guides the selection of various error monitoring, reports, and printer options. Enter the Performance Monitor screen with the PM command from the system control menu.

What Do You Order?
A D/I Mux III is required at both ends of the network as described in Figure 5. An A/B switch is required to switch the T1 transmission paths in a timely manner.

FDLP is required to collect CRC error reports. A printer is also required to keep an ongoing record of CRC errors.

T1 Interface Options

Solution
D/I Mux III offers a variety of T1 interfaces to meet all of your network's requirements.

The CSU functionality, a requirement of the public network, is contained in the Dual CSU Interface. A Dual CSU Interface also has the ability to perform loopback tests, which meet the requirement for the fiber optic portion of the network. A Dual Standard DSX-1 Interface supplies a basic connection to the digital cross-connect.

How Does It Work?
There are three varieties of Dual CSU Interface; the T1/DSX-1 with one CSU interface and one DSX-1 interface, DSX-1/DSX-1 with two DSX-1 interfaces, and the T1/T1 with two CSU interfaces. Dual CSU Interfaces offer test and loopback capabilities for the network and the end user. The Dual Standard DSX-1 Interface supplies two standard DSX-1 interfaces.

T1 Interface Options Table

Figure s6. T1 Interface Options

What Actually Occurs?
Every T1 interface option is used in the network, as shown in Figure 6. To supply the PBX Center with a connection to the PSN, a Dual CSU Interface with T1/T1 connections is used. This allows 48 DS0 voice channels to easily connect to the public network.

At the Data Center, the D/I Mux III connects to the DXC II with a Dual Standard DSX-1 Interface. The DXC II then routs the data channels to the corporate centers and the PSN.

Corporate Center One receives the information on a Dual CSU Interface with DSX-1/DSX-1 connections. Both the DXC II system and fiber optic system surrounding Corporate Center One require DSX-1 interfaces. The Dual CSU Interface functionality makes testing of the fiber optic link easy.

At the other side of the fiber optic link is Corporate Center Two with the required DSX-1 interface to the fiber optic network and a T1 interface to the PSN.

How Do You Set It Up?
The D/I Mux III at the PBX Center is installed with a Dual CSU Interface (T1/T1) and placed in the dual channel bank mode of operation.

The D/I Mux III at the Data Center is installed with a Dual Standard DSX-1 Interface and placed in channel bank mode.

The D/I Mux III at Corporate Center One is installed with a Dual CSU Interface (DSX-1/DSX-1) and placed in drop and insert mode.

The D/I Mux III at Corporate Center Two is installed with a Dual CSU Interface (T1/DSX-1) and placed in drop and insert mode.

What Do You Order?

• Dual CSU Interface (T1/T1)

• Dual Standard DSX-1 Interface

• Dual CSU Interface (DSX-1/DSX-1)

• Dual CSU Interface (T1/DSX-1)

Any intelligent D/I Mux III product (D/I Mux III, TWIN T1M, or the T1M CSU/DSU) accepts these T1 interfaces.