East Coast Datacom Nx8- Dual Composite MUX High-Speed 16-Port TDM Multiplexer, Nx8-DualMUX Operation Manual

FOR TECHNICAL SUPPORT CALL:

East Coast Datacom, Inc.

245 Gus Hipp Blvd., STE #3

Rockledge, FL 32955 USA

TEL: [phone] or [phone]

FAX: [phone]

WEB: www.ecdata.com

DOC # 166119

OPERATIONS MANUAL

Nx8- Dual Composite MUX

High-Speed 16-Port TDM Multiplexer

31 August, 2006

Manufactured by:

East Coast Datacom, Inc.

i

1 Introduction............................................................................................................................. 3

1.1 Network Configurations ..................................................................................................... 3

1.2 Planning ............................................................................................................................ 4

2 Key Functions ......................................................................................................................... 5

2.1 Multiplexer Operation ........................................................................................................ 6

2.1.1 Multiplexer .................................................................................................................... 6

2.1.2 Demultiplexer ............................................................................................................... 8

2.1.3 FIFO Buffers ................................................................................................................. 8

2.1.4 Channel Allocation / De-allocation ............................................................................... 8

2.1.5 Management Channel .................................................................................................. 9

2.1.6 Composite Port Operation ........................................................................................... 9

2.1.7 Channel Port Operation ............................................................................................. 12

2.2 System Operation ........................................................................................................... 14

2.2.1 Configuration Management Functions ....................................................................... 14

2.2.2 Non-volatile Parameter Storage ................................................................................. 15

2.2.3 Null Configuration Reset ............................................................................................ 15

2.2.4 System Reset ............................................................................................................. 16

2.2.5 Configuration Backup and Restoral to File ................................................................ 16

2.2.6 Configuration Copy Commands between Local and Remote Systems ..................... 16

2.2.7 Copying the Operating Systems from a Local to Remote System ............................ 17

2.2.8 Time and Day Clock ................................................................................................... 17

2.2.9 Node ID Information ................................................................................................... 18

2.2.10 Log-In, Log-Off and Change Password ..................................................................... 18

2.3 Backup, Restoral, and Bandwidth Assignment Operations ............................................ 18

2.3.1 Channel Failover Modes and Associated Parameters ............................................... 18

2.3.2 Expanded Bandwidth Configuration ........................................................................... 19

2.3.3 Redundant (or Hot Standby) Link Configuration ........................................................ 20

2.3.4 Backup with Prioritized Channels .............................................................................. 21

3 Hardware Installation ........................................................................................................... 29

3.1 Main Chassis ................................................................................................................... 30

3.1.1 AC Mains Power ........................................................................................................ 30

3.1.2 Chassis rack-mounting .............................................................................................. 30

3.1.3 Thermal requirements ................................................................................................ 30

3.2 Power Supply Modules ................................................................................................... 31

3.2.1 Power Supply Replacement ....................................................................................... 31

3.3 Processor Card ............................................................................................................... 31

3.3.1 Processor Card Replacement .................................................................................... 32

3.4 Port I/O Cards ................................................................................................................. 32

3.4.1 Port I/O Card Replacement ........................................................................................ 32

3.5 Troubleshooting .............................................................................................................. 32

3.5.1 Basic System Checks and Operation ........................................................................ 32

4 User Interface ....................................................................................................................... 35

4.1 Indicators ......................................................................................................................... 35

4.1.1 Processor Card .......................................................................................................... 35

4.1.2 Port I/O Card .............................................................................................................. 36

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4.1.3 Redundant Power Supply .......................................................................................... 37

4.2 Console Operation .......................................................................................................... 37

4.2.1 Console Setup ............................................................................................................ 37

4.3 Power-Up Login & Logoff ................................................................................................ 38

4.4 Menu and Screen Format ............................................................................................... 39

4.5 Menu Structure ................................................................................................................ 40

4.6 Help Menu ....................................................................................................................... 41

4.7 Top-Level Menu .............................................................................................................. 42

4.7.1 Composite Link Statistics [1] ...................................................................................... 42

4.7.2 Composite Configuration Menu [2] ............................................................................ 44

4.7.3 Channel Configuration Menu [3] ................................................................................ 47

4.7.4 Status & Configuration Functions Menu [4] ............................................................... 52

4.7.5 Test & Maintenance Menu [5] .................................................................................... 55

5 Appendix ............................................................................................................................... 59

5.1 Factory Default Configuration (Null Configuration) ......................................................... 59

5.2 Connector Pinout Diagrams ............................................................................................ 60

5.2.1 Channel Port Connectors (DCE) ................................................................................ 60

5.2.2 Composite Port Connector (DTE) .............................................................................. 61

5.2.3 Console Port Connector ............................................................................................. 62

5.3 Adapter Cables ............................................................................................................... 63

5.3.1 Composite Port V.35 Adapter Cable Connection Diagram ........................................ 63

5.3.2 Composite Port X.21 Adapter Cable Connection Diagram ........................................ 64

5.3.3 Composite Port RS-449 Adapter Cable Connection Diagram ................................... 65

5.3.4 Channel Port V.35 Adapter Cable Connection Diagram............................................ 66

5.3.5 Channel Port X.21 Adapter Cable Connection Diagram............................................ 67

5.3.6 Channel Port RS-449 Adapter Cable Connection Diagram ....................................... 68

5.3.7 Channel Port-to-Console Adapter Cable ................................................................... 69

5.4 Configuration Storage ....................................................... Error! Bookmark not defined.

5.5 Configuring an Nx8-DualMUX Link for Simplex Operation ............................................. 70

5.5.1 Behavior of System Management in Transmit Loopback .......................................... 70

5.6 Technical Specifications .................................................................................................. 72

5.7 Ordering Information ....................................................................................................... 73

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1

SAFETY WARNING

Always observe standard safety precautions during installation, operation and
maintenance of this product. To avoid the possibility of electrical shock, be sure to
disconnect the power cord from the power source before you remove the IEC power
fuses or perform any repairs.

PROPRIETARY NOTICE

The information contained herein is proprietary to East Coast Datacom, Inc. Any
reproduction or redistribution of this publication, in whole or in part, is expressly
prohibited unless written authorization is provided by East Coast Datacom, Inc.

WARRANTY NOTICE

WARRANTIES: East Coast Datacom, Inc. (hereafter referred to as E.C.D.) warrants
that its equipment is free from any defects in materials and workmanship. The warranty
period shall be three (3) years from the date of shipment. E.C.D.'s sole obligation under
its warranty is limited to the repair or replacement of defective equipment, provided it is
returned to E.C.D., transportation prepaid, within a reasonable period. This warranty will
not extend to equipment subjected to accident, misuse, alterations or repair not made by
E.C.D. or authorized by E.C.D. in writing.

PUBLICATION NOTICE

This manual has been compiled and checked for accuracy. The information in this
manual does not constitute a warranty of performance. E.C.D. reserves the right to
revise this publication and make changes from time to time in the content thereof.
E.C.D. assumes no liability for losses incurred as a result of out-of-date or incorrect
information contained in this manual.

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Digital Carrier

Network

Up to 128Kbps Aggregate Channel Bandwidth w/o Backup
(Links A & B may be unequal rate)

-OR­Up to 256 Kbps Aggregate Channel Bandwidth w/Backup ­HI & LO priority channels (Links A & B equal rate)

Nx8 DualMUX Nx8 DualMUX

<128 Kbps

<128 Kbps

Link A

Link B

T

T

T

T

T

T

T

T

Up to 16 terminal devices

Clock timing

Clock timing

1 Introduction

The Nx8-DualMUX is a modular, 16 Port Dual-composite TDM multiplexer for high-speed
serial data terminal equipment. It is designed to work in a paired, point-to-point configuration
over one or two synchronous composite clear-channel links of up to 128Kbps each.

The system may be configured with from 4 to 16 channel ports, operating at rates up to 38.4
Kbps asynchronous, or up to 64Kbps synchronous.

The system is configured and managed by the user through an RS-232 Console port terminal
interface to either a computer/laptop running a terminal emulation program, or a standard
ASCII dumb terminal.

1.1 Network Configurations

The Nx8-DualMUX may be used in Point-to-point applications with different types of
equipment and circuits. As long as the circuits between the two units is synchronous and
provides transparent data transport, the link should operate. Even geosynchronous satellite
delays up to 0.5 sec are tolerated without any problem.

Figure 1 shows an example of utilizing a service provider‟s digital carrier service. In most

such applications, the carrier‟s equipment provides a clock timing source at some multiple of

64 Kbps. If needed, the Nx8-DualMUX can provide timing at many n x 64Kbps rates, up to
2,048Kbps from an internal oscillator on one end of the link, and synchronize to that rate on
the other end. This is also helpful when connecting units back-to-back in limited distance
applications.

Figure 1 Point-to-point Link using Digital Carrier

The Nx8-DualMUX may also be used in conjunction with higher-rate multiplexing equipment
as a sub-multiplexer. An example of this is shown in Figure 2. The Nx8-DualMUX units may
each be assigned one or two ports on the larger multiplexer and those ports programmed for
operation at any of the selectable n x 8Kbps rates.

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4

1.2 Planning

Figure 2 Point-to-point Link as Sub-multiplexer

The network administrator must determine how the Nx8-DualMUX units will work in the
network and understand the applications that will utilize each of the available channels. Some
of this work is made easier by the fact that link bandwidth requirements are easily determined
by summing the bandwidth needs of each channel port that is planned to be used, and
adding the fixed overhead. Inband control signal transport should also be considered when
needed, as some bandwidth is required to support this function.

Additionally, the network administrator should have in mind other considerations that are
factors in planning for the installation. Some of these are:

1) Power requirements, including redundancy

2) Ventilation and cooling

3) Rack space requirements

4) Cabling & distances between equipment

5) Ease of access for maintenance

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Composite Port Interface (DTE)

Software-selectable interface types: RS-232, EIA-530, V.35*, RS-422/449*, X.21*
*(via cable adapter)

Selectable clock rates: 8Kbps to 128Kbps, in increments of 8Kbps

Internal Clock for local or back-to-back operation

Channel Port Interface (DCE)

Software-selectable interface types on ports 1, 5, 9 and 13: RS-232, EIA-530, V.35*, RS-422/449*, X.21*
*(via cable adapter)

Programmable Asynchronous (RS-232 only), or Synchronous operation on a per-port basis

Async data rates: 1200, 2400, 4800, 7200, 9600, 14.4K, 19.2K, 28.8K, & 38.4K (bits per second)

Synchronous data rates: all async data rates + 16K, 24K, 32K, 40K, 48K, 56K, & 64K (bits per second)

Programmable RTS to CTS delay: 0, 3, 7, 13, 26, or 53 (milliseconds)

Transmit data clock selection: TxC or TxCE

Multiplexing

Non-disruptive channel configuration / reconfiguration

Fixed overhead limited to 1600bps, for framing and in-band management channel (1200bps)

Option for in-band transport of RTS for remote DCD

Composite Link Backup and Restoral

Per-Channel Recovery and Priority Options

Measurement of composite link error performance

System Features

Console port for reconfiguration of linked local and remote systems via terminal

Universal AC power input, 85 – 264 VAC, 50/60Hz

Power Supply Redundancy option

Downline loading of firmware revisions

Backup and Restoral of configurations to/from PC

Hot-swappable, modular cards and power supply

2 Key Functions

This section presents the functional operation and concepts of the Nx64-DualMUX. Readers
should familiarize themselves with this section before proceeding to the Installation section.

Feature Summary

The major features of the Nx8-DualMUX are outlined in the following table:

Table 1 – Nx8-DualMUX Major Features

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Composite Port I/F

Multiplexer

.
.

Input

FIFOs

x16

.
.

Port Loop

Functions

Demultiplexer

.
.

Output

FIFOs

x16

.
.

Port Loop
Functions

Port Loops

Port
RxD

x16

Port
TxD
x16

Allocation

Memory

Frame

Generation

& Counter

Allocation

Memory

Frame
Synch.
Detect

& Counter

Mgt Link TxD

(from Proc)

Mgt Link RxD

(to Proc)

Loopback
Functions

MUX BLOCK DIAGRAM - DATA FLOW

Sync

2.1 Multiplexer Operation

The central hardware element of the Nx8-DualMUX is a multiplexer/demultiplexer function
through which all end-to-end user and management information flows. The drawing of Figure
3 provides a high-level reference diagram for this function. Other functions such as clock
synthesis and synchronization, backup and restoral of channels and links, control paths and
programming, and user interfaces are not included.

Figure 3 MUX Data Flow Diagram

2.1.1 Multiplexer

The Nx8-DualMUX incorporates both the ability to multiplex outbound data over the
composite link as well as demultiplex the same inbound data stream. Multiplexing is achieved

by generating a “frame”, which is a fixed-length, repetitive data pattern.

The frame consists of a frame bit followed by a fixed number of “timeslot” bits, each of which

is assigned to a specific data port that has been allocated. As the multiplexer scans across
the frame a bit at a time, it inserts a serial bit from the port buffer to which that timeslot bit is
assigned. Therefore, the bits forming a channel are always in the same position from frame to
frame.

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2.1.1.1 Timeslots and Channel Rates

The number of timeslots assigned to a channel determine the bandwidth of the channel,
Since the frame rate is constant, the greater the number of channel bits in the frame, the
greater the port rate that can be supported.

The basic frame rate is 400 frames-per-second, and each channel bit, or timeslot in the frame
provides 400 Hz of bandwidth available for allocation to a channel. This allows port rates that
are multiples of this rate to be supported. For example, 19.2KHz is 48 x 400 Hz, and
therefore requires 48 timeslots per frame.

Timeslots are assigned in a manner that distributes their placement throughout the frame.
The purpose of this method is to insure that the rate of arrival or departure of channel bits on
the composite port is approximately matched to the bit rate of the channel port, and therefore
minimizes the requirement for an elastic storage buffer for each channel.

In addition, by not requiring a pre-determined timeslot map for each channel or channel rate,
channels may be allocated and de-allocated from time to time without disrupting the
operation or data flow of other channels. In other words, newly allocated channels are fit into
the timeslot map wherever there are available timeslots, but do not affect those already
assigned.

The above concepts are illustrated in the diagram of Figure 4. In this simple case, the
composite frame is 20 bits, corresponding to an 8KHz link. The frame size could be chosen
as large as 320 bits (128KHz), but for simplicity 8KHz is chosen. Given that the frame bit
occupies 1 bit (400Hz), and the management channel 3 bits (1200Hz), 16 bits are left in
which to assign channel bandwidth.

The first channel, “a”, is 2400Bps and is assigned available timeslot positions 5, 6, 9, 12, 15,
and 18. (The pattern is unimportant, but noteworthy that the timeslots are distributed

throughout the frame, and their location in the timeslot map allocates them to channel “a”.
When channel “b” is allocated, also 2400Bps, the timeslots are chosen from among the

remaining available timeslots, but in a different placement and pattern. None of the timeslots

of channel “a” are disturbed in the process. When complete, there are still 4 timeslots

remaining corresponding to 1600Hz of bandwidth, enough for a 1200Bps channel, for
example.

Although this is a very simple example (8KHz composite is usually insufficient), higher link
rate examples may be configured and are assigned in the same way. All 16 ports may be
time-division multiplexed on the composite link given sufficient bandwidth. The 1600Hz
required for the framing bit and the management channel is fixed however, and must be
considered when planning channel allocation.

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8

F

20 - (320) bits

Da1Da

2

Da

3

Da

4

Da

5

Da

6

M1M2M

3

F Da1Da

2

Da

3

Da

4

Da

5

Da

6

M1M2M

3

Db1Db

2

Db

3

Db

4

Db

5

Db

6

Da

5

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Channel "a"

allocated = 2400Bps

Channel "b"

allocated = 2400Bps

. . .

F - Framing timeslot
M - Management channel timeslot
Da, Db - Data channel a or b timeslot

Figure 4 – Frame and Super-frame Multiplexing

2.1.2 Demultiplexer

Demultiplexing of the composite data stream is accomplished using the same timeslot
channel mapping as used for multiplexing. One difference is that the demultiplexer must first
locate the super-frame bit pattern in the data stream as a reference point for all other
timeslots that follow. Once the repetitive super-frame bit pattern has been recognized and
located, the demultiplexer is said to be in “synchronization” with the remote multiplexer.

Having located the super-frame bit pattern, the demultiplexer can send each arriving bit
following the framing bit to the specific channel port buffer to which it is assigned, including
the management channel.

2.1.3 FIFO Buffers

Timeslots comprising a single channel need not be evenly distributed throughout the frame
(and in fact, seldom are). For this reason, serial data bits associated with a given port are
often transmitted and received in patterns of bursts and lulls that is much different than the
fixed bit rate of the port.

While the average rate of channel bits on the composite link will always equal that at the port,
it is necessary to buffer a small number of bits for each channel between the port and the
composite link. These buffers, referred to as “FIFOs” (First-In, First-Out buffers) are memory
arrays used for the purpose of regulating the flow of data.

2.1.4 Channel Allocation / De-allocation

Channels are associated with a corresponding port number; thus Port 7 is tied to Channel 7,
for example. The user determines which ports to utilize, their interface speeds, and other
parameters associated with the port interface or the channel, and then goes about
configuring them.

Prior to the channel being allocated, the user is able to freely modify these parameters.
However, until the channel is allocated, no data can be exchanged between the two ports at
each end of the link. When the channel is allocated, the bandwidth and timeslots are
assigned and the port becomes active.

All of the channel and port parameters may be modified after a channel has been allocated.
In those cases where the channel bandwidth is altered, either by changing the channel rate

or modifying the transport of control status, the system will automatically de-allocate the
channel and then subsequently re-allocate the same channel with the new parameters. This

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will result in a momentary interruption or loss of data while the process takes place, but

9

minimizes the duration of the interruption and eliminates the need for the operator to
manually enter the sequence of commands.

The Nx8-DualMUX has an additional feature that re-allocates channels to new timeslots
when the composite link rate is changed by the user. This is particularly important when the
composite link rate is decreased, with a corresponding reduction in the size of the timeslot
allocation memory. Without re-allocating the port channels to fit in the smaller allocation
memory, many of the channels would lose the ability to pass end-to-end data.

2.1.4.1 Non-disruption of Channels

The process of configuration of any one channel is non-disruptive to the flow of data among
other active (allocated) channels. Thus any channel may be allocated, de-allocated, or

modified in any of it‟s parameters, without risk of disrupting data among those ports which are

in use and do not require reconfiguration.

2.1.4.2 Total Bandwidth Availability

Channels are allocated by their required bandwidth, and the total composite bandwidth
needed to support all active channels is simply the sum of the channel bandwidth
requirement, plus the fixed overhead of 8000bps for framing and the management channel.

When a channel is de-allocated it makes available that same bandwidth, added to any
available pre-existing bandwidth, to be used by other channels at a later reconfiguration
point.

2.1.5 Management Channel

The Nx8-DualMUX reserves a fixed sub-channel of 1200 bps for end-to-end, embedded
communication between a pair of linked systems. Once both units have become
synchronized, this channel is used for system management functions. These functions
include remote user configuration, message and command acknowledgments, status
reporting, program downloading, and test/maintenance commands.

2.1.6 Composite Port Operation

The composite port carries all end-to-end information between the systems comprising a
linked pair of multiplexes. As a DTE interface, a data clock signal(s) at the port is a required
input from an attached DCE device. The clock rate must be one of several selectable
multiples of 8kHz (see Table 1). Additionally, the Nx8-DualMUX composite port must be
configured to that same rate in order for the internal port clock generators to work properly.

2.1.6.1 Internal Source Clock Timing

It is possible to use the Nx8-DualMUX as a source of timing on one end of a link. This
requires a special cable arrangement as shown in Figure 5 and performing the required
configuration steps to program the composite port. In this example, multiplexer 1, on the left,
generates a clock signal on TXCE based on the internal crystal oscillator. This clock is used
to clock out TxD. On the opposite side, the transmit clock and data signals are crossed over
to the receive side and the clock is used to latch RxD. As received, the RxC signal on
multiplexer 2 is looped back to the clock source block, and used as the outgoing TXCE. The
transmit clock and data signals are crossed over again in the same manner as RxC and RxD,
respectively. Thus all clocks are derived from a single source.

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RXD

RXC

TXD

TXC

TXCE

RXD

RXC

TXD

TXC

TXCE

Loop-timed

DTE

Internal-timed

DTE

Tx data

latch

Transmitted
TXCE is used to
clock out TXD

Cross-over "null modem"

cable connections

Rx data

latch

Rx data

latch

Tx data

latch

COMPOSITE DTE to DTE CONNECTION DIAGRAM

Internal

Oscillator

Clock

Source

RxC

Loop

Clock

Source

Transmitted
TxCE is used to
clock out TXD

Multiplexer 1 Multiplexer 2

TxCE Enable

TxCE Enable

Figure 5 Composite port cable diagram for DTE-to-DTE connections

Other non-symmetrical arrangements based on this approach to connect with transmission
equipment requiring an external timing source are possible.

2.1.6.2 Hardware Interface Options

The composite port is configurable for three different electrical interface standards:

1) RS-232

2) V.35 (V.11 and V.24)

3) EIA-530 (also includes RS-449 and X.21 with cable adapter)

These options are programmable and do not require the setting of hardware straps or
switches. However, support for standard connectors for V.35, RS-449, and X.21 requires
cables, which adapt between the native composite DB-25 connector and the desired interface
connector.

2.1.6.3 Link State Option

The composite link may be enabled or disabled by command. When the link is disabled, no
information is transmitted, and received data is ignored. Since received data is not
recognized, synchronization as reflected in the SYNC status is reset and synchronization is
lost. No information can be exchanged between systems via the management channel when
the composite link is disabled.

When the composite link is enabled, complete frames are transmitted along with the
management channel. The received data is accepted, and if a valid framing pattern is
detected, the system will synchronize and begin receiving the management channel data
from the remote system.

2.1.6.4 Link Rate Option

The operator may modify the expected received clock rate of the composite port. This may be

done on either the local or remote system. In either case, a system that is in synchronization
will lose sync until the actual DCE matches the selected rate. Once completed on remote
system, a change in the selected clock rate will result in the loss of the management channel
and the ability to send any subsequent commands to the remote system until the remote
DCE clock matches the selected rate.

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RXD

TXD

RXD

TXD

Composite

Port

Receive Loopback

RXD

TXD

RXD

TXD

Composite

Port

Nx8-MUX

Transmit Loopback

Nx8-MUX

For the Nx8-DualMUX, any parameter entry to the composite link rate causes the system to

1) resize the timeslot allocation memory map to the new frame size, 2) re-allocate all
channels with non-zero clock rates to fit in the new allocation map, and 3) stores the
complete configuration in non-volatile memory. Channels that have been previously de­allocated, but have a rate assigned to them other than zero, will be re-allocated at the rate
assigned, beginning with channel 1 and proceeding in an ascending order up to channel 16.

Should there be insufficient composite bandwidth at the new rate to accommodate all
channels at their assigned rates, the system will de-allocate those channels by number
higher than last channel allocated, but will leave their assigned rate unchanged. Thus for
example, if channels 1 through 12 fit into the new capacity of the composite link at their
assigned rates, but channel 13 will not, then channels 13 through 16 will be de-allocated and
their assigned rate will remain unchanged. If at a later time, the composite link rate is
increased and one or more of channels 13 through 16 can be accommodated, they will be
allocated bandwidth at their previously-assigned rate.

As a result of the above channel re-allocation, all channels will potentially be disrupted and
cannot be returned to service until both local and remote systems have been given equivalent
commands to modify the composite link rate. Even then, unless the channel bandwidth
parameters in both systems are identical, channel timeslots will not match. In such cases, the

operator should use the “Copy Mixed Configuration to Remote” command (see section

2.2.6.3 ).

2.1.6.5 Control Signal Leads

The state of the RTS lead on the composite port may be selected by configuration option.

The DTR lead is set ON when electrical power is applied to the system.

2.1.6.6 Composite Port Loop Options

The Composite Port may be put into one of two loop configurations by user command. These
two loop modes are termed Receive loopback and Transmit Loopback and are mutually
exclusive.

The diagram of Figure 6 illustrates both modes. In receive loopback (left), the same data that
is received at the composite port is also sent to the transmit side of the interface in place of
the data that is normally sent on the TxD lead.

In transmit loopback (right), the same data that is transmitted at the composite port is also
returned to the receive side of the interface in place of the data that is normally received on
the RxD lead.

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Figure 6 – Composite Port Receive and Transmit Loopback Modes

12

2.1.7 Channel Port Operation

The 16 channel ports may be configured individually according to their various port options.
All ports are implemented as DCE interfaces and provide clocking to the attached terminal
equipment.

Any supported channel rate may be configured on any channel, from 1200 bps to 64Kbps.
The only remaining limitation being that the aggregate channel rate of all ports may not
exceed the available user bandwidth of the composite link. The channel rate applies to both
channel port pairs and both ports must operate at the same rate.

2.1.7.1 Hardware Interface Options

Any of the 16 channel ports will operate as RS-232 interface types. In addition, each of the
four quad I/O port cards possesses a single port that can be configured as an EIA-530
interface, or a V.35 type interface (RS-449 and X.21 port connectors are supported through
an attached adapter cable with EIA-530 operation; V.35 requires an adapter cable for a
compatible port connector.)

2.1.7.2 Sync and Async Timing Modes

Each channel port may be configured for operation in either RS-232 synchronous or
asynchronous mode. For asynchronous mode, in order to properly set up the port, the user
must be aware of the character size and stop, start, and parity settings of the terminal
equipment. The bandwidth required on the composite link for asynchronous channels is equal
to the baud rate.

Both ports comprising a channel must be configured in identical timing modes (i.e., both sync
or both async).

If a channel port is set to operate as an EIA-530 or V.35 interface, it must use synchronous
timing.

2.1.7.3 Clocking Option

Although the channel ports cannot accept as ynchronous clock timing from an attached
device, each port can be configured to receive the transmit clock on the TxCE lead and use
this signal for clocking in the data on the TxD lead.

In this case, it is up to the user to configure the attached equipment to synchronize with the
outgoing RxC or TxC, otherwise data errors will occur.

2.1.7.4 RTS / CTS Delay Option

An option exists on each channel port to configure the CTS control lead signal level output to
follow the RTS control lead signal level input at the port. Various delays may be selected,
from zero delay up to 53mS. Additionally, the CTS control lead may be set to either an ON
state or an OFF state.

2.1.7.5 DCD Source Option

The DCD (RLSD) control signal lead at the channel port may be configured for one of two
modes.

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13

TXD

RXD

Channel

Port N

Nx64-MUX

(Channel N)

RxD

'MARK'

Local Loopback

(Channel N)

TxD

TXD

RXD

Channel

Port N

Nx64-MUX

(Channel N)

RxD

Local & Remote Loopback

Channel

Port N

TXD

RXD

Nx64-MUX

(Channel N)

RxD

'MARK'

Remote Loopback

(Channel N)

TxD

(Channel N)

TxD

In the first and default mode, the DCD signal follows the state of the composite
synchronization detector. Thus if SYNC is ON, DCD at the channel port is ON, and OFF if
SYNC is OFF.

In the second mode, the DCD signal may be configured to respond according to the state of
the corresponding channel port RTS input at the far end of the link. This configuration option
may be set at either end, or both ends of the channel as needed. If the option is set at one
end of the channel, the other may be freely set to one of the other two modes.

2.1.7.6 Channel Port Loop Options

Each channel port may be selectively put into three loop mode configurations. The two loop
modes are termed Local Loopback and Remote Loopback and may be used singly, or in
combination.

The diagrams of Figure 7 illustrate the data paths followed for each of the three combinations
of loop modes. In local loopback (top, left), the data that is received at the channel port TxD
lead is sent to the RxD lead of the interface in place of the data that is normally sent, while a
constant “Mark” signal is sent to the transmit side of the channel.

In remote loopback (top, right), the data that is received from the channel is sent back to the
transmit side of the channel in place of data that is normally input from the port TxD lead,
while a constant “Mark” signal is sent to the RxD lead.

When both local and remote loopback are invoked, the two loop functions are overlaid with
the resulting loop paths as shown in the bottom diagram of Figure 7.

Figure 7 Three Channel Port Loopback Modes

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14

2.2 System Operation

2.2.1 Configuration Management Functions

The configuration management functions are those features to which an operator has access
for the purpose of installing, and configuring a working end-to-end multiplexer link. Many of
these functions are self-explanatory and are thoroughly addressed in Section 4.2-Console
Operation.

However, certain fundamental aspects of the configuration management process are
noteworthy and are discussed in the following sections.

2.2.1.1 Local / Remote Systems

When configuring a linked pair of systems, the operator will be using a console attached to
one system or the other. Since there are no built-in distinctions between a local and a remote
multiplexer, the reference point of local or remote is solely dependent on the point of view

from the operator‟s console. The local system is the one to which the console terminal is

attached, and the far-end system is the remote system.

2.2.1.2 Composite Port Configuration

The composite port configuration is critical to the configuration process as a first step for two
reasons:

First, by configuring the composite ports and establishing a link between two attached
multiplexers, both systems may be configured simultaneously and with compatible
parameters.

Second, the composite port rate determines the aggregate bandwidth (and frame size)
available to the channels. If channels are allocated prior to establishing the composite port
rate, then they must be re-allocated (repeat de-allocate/allocate steps) in order to map them
into the new multiplexer frame size.

Because it is expected that the operator will perform much of the configuration process on
linked systems, the ability to configure the composite port on a remote system is restricted.
Thus the potential for an operator to inadvertently bring down the link (and the in-band
management channel) to a non-recoverable state is reduced.

The ability to change a remote systems composite link rate is not restricted however. The use
of this function should be approached very cautiously, as a change in the programmed link
rate has the same effect as changing the link clock, i.e., the link will immediately become
inoperative until a new common clock has been re-established at the same rate as
programmed in both multiplexers.

As another exception for troubleshooting purposes, the Receive Loopback function on the
remote composite port is allowed since it can be controlled once invoked.

2.2.1.3 Channel and Port Configuration

While a channel is an end-to-end entity, a port is physically independent and separately
configurable on each end of the channel. This distinction is important, because it means that
the operator need only make changes to channel parameters (i.e., rate and channel state)
once on linked systems, and there is no local or remote viewpoint for these parameters.

One exception to the above statement is that of the option for the DCD source on any Nx8K
(i.e., 56Kbps and higher) channel rates (see section 2.1.7.5 – DCD Source Option). When the
DCD source for a port is selected to follow the far-end RTS, an additional 8Kbps of channel

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15

bandwidth is added to carry the control signal end-to-end. While bandwidth is added in both
directions, only the port selected to respond to the RTS from the opposite end of the channel
will operate in this mode. If this option is changed while the channel is allocated, there will be
a momentary disruption of the channel data as the system re-configures the channel.

For port parameters, local and remote ports must be configured separately. However, both
local and remote ports may be configured in the same session from either end of the
multiplexer link.

NOTE: Two unlinked systems, whose channels have been configured with identical
parameters in separate sessions, may not pass end-to-end channel data correctly when they
are subsequently linked. Without coordinating the channel allocation sequence between
linked systems via the management channel, multiplexer frame maps are not likely to match.

2.2.2 Non-volatile Parameter Storage

Operating configuration parameters for the Nx8-DualMUX that are modified by the user are
first written in random-access-memory (RAM). As long as the power is not turned off or the
mux is not reset, the system will continue to work with these parameters in effect. This is
referred to as the “working configuration”.

When the user is satisfied with the working configuration parameters as they are set, or
simply wishes to save the working configuration for a later editing session, that configuration
may be stored in non-volatile (FLASH) memory. Once saved, the same configuration will be
restored to RAM each time the power is turned on or a system reset occurs. This
configuration is called the “stored configuration”.

One exception to the preceding paragraph occurs in the case of channel loopback functions.
Both local and remote channel loops when put into effect by the user via a menu option, are
immediately stored in FLASH memory. Therefore, it is not necessary to save a channel
loopback state to preserve it‟s status in the event of a power loss to the system.

Other commands available to the user also result in storing the working configuration to

FLASH memory. These include the commands “Copy Configuration to Remote”, “Enter Node
ID”, and modifying the Composite Link Rate. In most cases, the storing of configuration

information is synchronized on both Local and Remote systems, via the management
channel.

A diagram illustrating the operations which result in changes to the working and stored
configurations and the effect on both local and remote systems may be found in Appendix
section Error! Reference source not found.-Error! Reference source not found..

2.2.3 Null Configuration Reset

A working configuration may be erased and returned to a default non-functional condition
through a null configuration reset. This operation de-allocates all channels, resets all channel
ports to a standard default condition, and disables the composite port on the local system.

This operation does not erase the configuration stored in FLASH memory

NOTE: The null configuration reset operation affects only the LOCAL system. Thus channels
that are allocated on the remote system will appear unallocated on the local system. This
command should only be used as a last resort in order to re-initialize a configuration that
cannot be easily rectified. In most cases, this operation should be performed on both local
and remote systems before proceeding to build a new configuration.

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2.2.4 System Reset

A system reset results from either 1) powering up the system, or 2) a System Reset
command. A system reset command performs identically the same functions as a power-on
reset, without having to cycle the power.

When a system reset occurs, the firmware containing the operational programs, including the
program for the hardware, are loaded from FLASH memory into both RAM and the FPGA,
respectively, where they are executed and reside until the power is removed.

Upon a system reset, configuration data is also loaded from FLASH memory into the working
configuration maintained in RAM, where it may be modified under user control over the
course of operation. If a modified working configuration has not been previously stored in
FLASH memory, the modification will be lost after a subsequent system reset command.

2.2.5 Configuration Backup and Restoral to File

Two separate processes allow the working configuration of an Nx8-DualMUX system to be
stored to a disk file on a computer, and, to allow a previously stored disk file to replace the
stored configuration within a system. Together these two processes constitute configuration
backup and restoral and are useful to reduce the time required to configure a system that
does not conform to a desired configuration.

The process of configuration backup and restoral is detailed in sections Error! Reference
source not found. and Error! Reference source not found..

2.2.6 Configuration Copy Commands between Local and Remote Systems

A configuration stored on a system may be copied by command to a remote system across
an operating link. Before this operation may take place, both systems must be in
synchronization with each other to allow the management channel to transport the
configuration data from one system to the other.

2.2.6.1 Copying the Local Configuration to the Remote System

Using this command, all parameters of the local system‟s working configuration are sent to
the remote system and copied into that system‟s stored configuration. At the same time the

local system also performs a store operation of the working configuration, such that both
systems have identical stored configurations.

It should be noted that individual port configuration parameters are also copied to the remote
system and duplicated, as these will often need to be configured differently on local and
remote ends of the channel. See section 2.2.6.3.

2.2.6.2 Copying the Remote Configuration to the Local System

Using this command, all parameters of the remote system‟s working configuration are
requested and received by the local system and copied into that system‟s stored

configuration. . At the same time the remote system also performs a store operation of the
working configuration, such that both systems have identical stored configurations.

It should be noted that individual port configuration parameters are also copied to the local
system and duplicated, as these will often need to be configured differently on local and
remote ends of the channel.

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2.2.6.3 Copying a Mixed Configuration from a Local to Remote System

Using this command, the configuration parameters of the local system are copied to the
remote in a similar manner as described in section 2.2.6.1 above, with the following
difference:

Remote port parameters that have been stored in non-volatile memory on the local system
and which may differ from those of the local system, are sent to the remote system to
become that system‟s new port parameters.

The stored parameters for the remote system are gathered by the local system automatically
and periodically while the systems are linked, but are only stored in non-volatile memory as
the result of an operator command. Therefore, the restoral of remote port parameters using
this command, will only be to the state that existed prior to the most recent working
configuration store operation.

The automatic gathering of remote port parameters as described applies to both systems, as
either may be regarded as remote or local at different times, relative only to the end of the
link at which commands are entered.

2.2.7 Copying the Operating Systems from a Local to Remote System

Three menu commands provide the ability to update the operating system (firmware) on a
remote system. Because of the possibility of a download of such a large file and the difficulty
of reversing an update to the operating system once it has been committed to FLASH
memory, the command for copying the operating system across the management channel
does not store the result in FLASH memory.

To completely update the operating system on the remote system, the operator must first
execute the Copy Local Operating System to Remote command. This saves a copy of the
local operating system in a temporary area of RAM. NOTE: If this step fails to complete
properly, the operator should not attempt to soft boot the remote system.

If the first step completes successfully, the next step is to execute the Soft Boot Remote
System command. This results in the just-saved firmware replacing the operating system in
RAM, and restarting execution with the new operating system. NOTE: If the remote system
does not give an indication that it has accepted the soft boot and is working normally, the
operator may revert to the current remote operating system by insuring that the remote
system is reset, either by command, or a power cycle. The remote system will then re-boot
from FLASH memory.

Once the remote system has successfully soft booted and is operating in sync with the local
system, the final command to Copy Remote Operating System to Flash is executed. This
step preserves the new operating system in non-volatile memory, such that it will always be
executed after a reset or a power cycle. Note: An operator should never execute this final if
there is any doubt that the new operating system is functioning correctly

2.2.8 Time and Day Clock

Each system possesses a day and 24-hour time clock that is initialized with a system reset
(by command or power-on), or by explicitly setting the time manually via a menu selection
and entry.

Since the clock is not an internal battery-backed calendar clock, the system reset initializes
the time to “000 00:00:00.00”, based on a format of: ddd hh:mm:ss.ss. Days are numbered
sequentially in decimal notation, beginning with day 000.

When the time is set manually, only the hour (0-23) and minute (0-59) fields may be set by
the operator.

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CAN BE

BUMPED

CANNOT BE

BUMPED

CAN BE

BUMPED

CANNOT BE

BUMPED

SEEKS BACKUP

NO BACKUP

(FIXED)

HIGH

LOW

PRIORITY MATRIX (FAILOVER MODES)

2.2.9 Node ID Information

A unique node name, of up to 20 alphanumeric ASCII characters, may be entered into the
non-volatile memory of each system in order to identify that system in the customer‟s
network.

The node id is displayed on the second line of every menu screen.

2.2.10 Log-In, Log-Off and Change Password

When the system is powered-on, or after a reset command, the operator must login in order
to access the management system. Once logged in, the operator may change the password
at any time via the Change Password command on the Log In Menu.

The system is initially programmed with the password “default” when shipped from the
factory. This permits the operator the means to initially login and establish a personal
password.

If the password is lost, the customer should contact East Coast Datacom, Inc. for instructions
on how to gain access to the Change Password screen entry function.

2.3 Backup, Restoral, and Bandwidth Assignment Operations

The Nx8-DualMUX allows for the distribution of channel bandwidth over two aggregate links,
and for the restoral of specific channels to an operational link under single-link failure
conditions. The flexibility of bandwidth distribution and fault-tolerance offers many options to
configuring a system. This section will address this facet of operation and some of the
possible configuration scenarios.

2.3.1 Channel Failover Modes and Associated Parameters

Before considering system configurations, it is important to understand channel failover mode
assignments. Channel failover modes determine under what conditions a channel is switched
to the alternate composite link from it‟s home composite link (the one to which it is originally
assigned). Priorities also determine if a channel circuit is to be bumped for a higher priority
channel. Other parameters associated with the channel affect the backup clock rate and
restoral time.

2.3.1.1 Failover Modes

There are two priority attributes, each with two possible values. These can best be
represented in the following matrix and together define the failover modes:

Table 2

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LINK A (e.g. 128Kbps)

EXPANDED BANDWIDTH CONFIGURATION

LINK B (e.g. 128Kbps)

Total Bandwidth = 256Kbps

(less 2 x 1600b/s link overhead)

Channel

Port #s

Channel

Port #s

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Timeslot

Map A

Timeslot

Map B

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Timeslot

Map A

Timeslot

Map B

The High/Low attribute determines whether a channel can be bumped or not, to make room
for another channel. High priority channels cannot be bumped, even by another high priority
channel. Low priority channels may only be bumped by high priority channels.

The Seek Backup/No Backup attribute defines whether a channel will be switched to the
backup link subject to available bandwidth and priority.

2.3.1.2 Failover Port Clock Rate

The failover rate is a channel port clock rate which may be different, typically lower, than the
channel rate on the primary, or home link. The purpose of this option is to allow a greater
number of backed-up channels to be accommodated on a single surviving link where
available bandwidth becomes more critical.

2.3.1.3 Channel Restoral Timer

Each channel may be configured with a timer that determines how and when the channel is

restored to it‟s home link when that link returns to service. This helps alleviate a channel

hopping back and forth under intermittent composite link conditions and creating circuit
disruptions to the terminal device.

In addition to time settings for this option ranging from immediate to one hour, a manual
choice is available. For this option, the channel will not be restored until either 1) the user
modifies the timer to a finite delay, or 2) the composite link on which the channel is currently
backed-up fails, AND the home link on which the channel was originally assigned is in
service.

2.3.2 Expanded Bandwidth Configuration

One of the simplest configurations using the dual link support in the Nx64 Dual Mux is that of
expanding the aggregate link capacity of the multiplexer up to 4.096 Mbps. With two links
between units, each channel may be assigned to either Link A or Link B, until the total
bandwidth available on both composites is consumed.

Figure 8

In the figure above, channels are assigned as needed to either of the composite links. It is not
required that the two links be of equal rate since the need may simply be for more aggregate
channel bandwidth than is available on a single link. In this example, channels 1, 3, 7, 8, 9,
10, 12, and 15 are assigned to Link A and channels 2, 4, 5, 6, 11, 13, 14 and 16 are assigned
to Link B.

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20

-- No channel data traffic --

Primary LINK A (e.g. 128Kbps)

REDUNDANT LINK CONFIGURATION

Backup LINK B (e.g. 96Kbps)

Channel

Port #s

Channel

Port #s

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Timeslot

Map A

Timeslot

Map B

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Timeslot

Map A

Timeslot

Map B

1) Normal State: Before fault, or after automatic restoral

-- Failed Link --

Primary LINK A (e.g. 128Kbps)

Backup LINK B (e.g. 96Kbps)

Channel

Port #s

Channel

Port #s

2) Backup State: After Link A fault

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Timeslot

Map A

Timeslot

Map B

1

2

3

4

5

6

7

8

9

10

11

12

13

14

15

16

Timeslot

Map A

Timeslot

Map B

Assuming no channel backup switching is required, all channels should be configured for a
failover mode such that they do not seek backup, i.e., their assignment to either Link A or
Link B is fixed, regardless of the state of those links. In such a case, high or low priority will
not matter, since there is no channel switching activity.

2.3.3 Redundant (or Hot Standby) Link Configuration

Another simple configuration example, but quite different than the previous, is that of the
redundant link, shown in Figure 9. In this case, one link, the primary link, carries all channel
traffic under normal conditions. The other link is defined as a backup, or hot standby,
available to accept channels switched over should a failure occur on the primary link.

The backup link does not necessarily need to be of equal rate as the primary, but certainly
should not be greater. If the backup capacity is less than the primary, then some channels
may not be accommodated on the backup should a loss of the primary link occur.

In the figure above, all channels are assigned to a single primary link, in this case Link A. In
the normal state, both links are in service and all channel traffic is on the primary link. Should
a failure occur on Link A in this example, the system will switch channels to the backup link,

assuming it is operational.

If the backup link has the same rate as the primary link, a switch-over of all channels may
occur. In this example, since Link B has a lower rate and channel capacity, some channels
may not fit in the bandwidth available. As shown, channels 4, 11, and 13 are out of service
and are not switched to the surviving link.

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Figure 9