GarrettCom MAGNUM 6KM User manual

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Corporate Headquarters
GarrettCom, Inc.
47823 Westinghouse Drive
Fremont, CA 94539
Phone [phone]
Fax [phone]
Website: http://www.GarrettCom.com
email [email protected]
Magnum
Personal Hubs
Installation and User Guide

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Magnum


Personal Hub


Installation and User Guide
Part #: 84-00023 (Rev B)
Trademarks
Ethernet is a trademark of Xerox Corporation
NEBS is a trademark of Telcordia Technologies
UL is a registered trademark of Underwriters Laboratories
GarrettCom, Magnum and Personal Switch are trademarks and Personal Hub is
a registered trademark of GarrettCom, Inc.
Important: Magnum Personal Hubs contain no user serviceable parts.
Attempted service by unauthorized personnel shall render any and all
warranties null and void. If problems are experienced with a Magnum Personal
Hub, consult Section 5, troubleshooting, of this User Guide.
Copyright 2001 GarrettCom, Inc. All rights reserved. No part
of this publication may be reproduced without prior written permission from
GarrettCom, Inc.
Printed in the United States of America.

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Contacting GarrettCom, Inc
Please use the mailing address, phone and fax numbers and email address listed
below:
GarrettCom, Inc.
213 Hammond Ave.
Fremont, CA 94539
Phone [phone]
Fax [phone]
Website: http://www.GarrettCom.com
email [email protected]
Federal Communications Commission
Radio Frequency Interference Statement
This equipment generates, uses and can radiate frequency energy and if
not installed and used properly, that is in strict accordance with the
manufacturer's instructions, may cause interference to radio communication. It
has been tested and found to comply with the limits for a Class A computing device
in accordance with the specifications in Subpart J of Part 15 of FCC rules, which
are designed to provide reasonable protection against such interference when
operated in a commercial environment. Operation of this equipment in a
residential area is likely to cause interference, in which case the user at his own
expense will be required to take whatever measures may be required to correct the
interference.

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TABLE OF CONTENTS Page
1.0 SPECIFICATIONS............................................................1
1.1. Technical Specifications.....................................................1
1.2 ORDERING INFORMATION............................................3
2.0 INTRODUCTION.............................................................4
2.1 Inspecting the Package and Product ....................................4
2.2 Product Description............................................................5
2.3 Features and Benefits...........................................................7
2.4 Applications.........................................................................9
3.0 INSTALLATION ..................................................................10
3.1 Table-Top or Shelf Mounting...........................................10
3.2 Wall (or Vertical Surface) Mounting.................................11
3.3 Twisted Pair Connections..................................................12
3.4 AUI Connection (Models H40A and H80A only).............12
3.5 Switchable Up-Link Feature..............................................13
3.6 Cascading Personal Hubs with the Up-Link Port ..............14
4.0 OPERATION...................................................................15
4.1 Functional Operation, Use of LED Indicators...................15
5.0 TROUBLESHOOTING ..................................................16
5.1 Before Calling for Assistance............................................16
5.2 When Calling for Assistance .............................................17
5.3 Return Material Authorization (RMA) Procedure.............17
5.4 Shipping and Packaging Information.................................18
APPENDIX A: WARRANTY INFORMATION ..........................18
Revisions
Rev C 04/01: Change the company name to GarrettCom, Inc. (Formerly it
was Garrett Communications). There are no changes to the content of the
material at this time.
Rev A 04/97 : This revision is the initial release of the Magnum
Personal Hub user manual.

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The Magnum Line
ETHERNET CONNECTIVITY PRODUCTS
"DESIGNED AND MANUFACTURED IN THE USA"
OVERVIEW
GarrettCom, Inc.offers the premium-quality Magnumline of Ethernet LAN
connectivity products with industry-standard functionality and built-in fiber
configurability. Magnum products are designed for use in demanding Carrier Class,
Industrial Grade and OEM applications where reliability is a primary consideration.
4K-Series Switches, 100 & 10Mbps, copper ports with optional
fiber port, with auto-negotiating full switching performance
Quad-Series Fiber Switches, 100 & 10Mbps, fiber and copper
ports, mixed-speed and mixed-media types, full switching
performance
“Outdoor” Ethernet Switch, for temperature uncontrolled locations
6 10/100 and 2 100Mb fiber ports, can be connected in strings
Mixed-Media Fiber Hub, 16-port Stackable, 10/100 auto-sensing
Dual Speed 8-port and 16-port Stackables, 10/100 auto-sensing
Stackable Hubs, SNMP Optional
10Mb series and 100Mb series, both w/ optional port modules
Personal Switches, 10/100Mb
8 port dual speed, Auto-negotiable with fiber option
Personal Hubs, 100Mb or 10/100Mb
8-port, with two switched ports (1 fiber built in)
Personal Hubs, 10Mb series
8-port + AUI, stackable to 5 high, + optional BNC of fiber port
8 or 9-port and 4 or 5-Port Personal Hubs, w/ man. up-link sw.
Media Converters, 10Mb and 100Mb series
All media combinations, incl. fiber ST, SC, mm., single mode
The “X-line” of configurable MiXed Media products:
Stackable Concentrators, SNMP optional, 13-Ports
Mini-Concentrators, 7 Ports, Repeaters, 2-Ports
Repeater Port Modules (RPMs),6 types for Ethernet media
Bridge Port Modules (BPMs), 4 types, for segment isolation
Fan-Outs, 10Mb series
2, 4 and 8 Port Models
Transceivers, 10Mb and 100Mb series 10Mb Mini-Transceivers
and Coax Models, All Types - Apr, 01

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1.0 SPECIFICATIONS
1.1. Technical Specifications
Performance:
Data Rate: 10 Mbps
Partitioning: Enforced after 32 consecutive collisions.
Reconnect: Occurs after 512 bits error-free transmission.
Maximum Ethernet Segment Lengths:
10BASE-T (Unshielded twisted pair) - 100 m (328 ft)
10BASE-T (Shielded twisted pair)- 150m (492 ft)
AUI Drop Cable - 50 m (164 ft)
Network Standards:
Ethernet V1.0/2.0 IEEE 802.3: 10BASE-T, 10BASE5.
(Magnum Personal Hubs are physical layer standard Ethernet products, and
operate in networks independently of all software.)
Operating Environment:
Ambient Temperature: 32ºF to 122ºF (0ºC to 50ºC)
Storage Temperature: -20ºC to 60ºC
Ambient Relative Humidity: 10% - 95% (non-condensing)
Power Supply (External):
Power Input: 95 - 125 vac at 60 Hz for "-d" Models,
200 - 250 vac at 50 Hz for "-i" Models, which have
IEC power cable connector in the external power unit.
Power Consumption: H40A, H50: 6 watts max.; H80A,
H90: 10 watts max.
Connectors:
H40A: 4 front shielded RJ-45 (1 with up-link switch), 1
rear AUI, female with slide lock.
H50: 4 front shielded, RJ-45, 1 rear shielded RJ-45 with
up-link switch.
H80A: 8 front shielded RJ-45 (1 with up-link switch), 1
rear AUI, female with slide lock.
H90: 8 front shielded RJ-45, 1 rear shielded RJ-45 with
up-link switch.
(Shielded 10BASE-T connectors accept either unshielded or shielded
wiring lugs for standard twisted pair media wiring.)
The regular RJ-45 ports support the standard for hubs-to-users twisted pair wiring: pin 1= receive+, 2 =
receive-, 3 = transmit+, 6 = transmit-, other pins not used. The RJ-45 port with the MDI-X switch is
normally the same, but when switched it supports the standard for up-links using twisted pair wiring, i.e., the
transmit and the receive pairs are exchanged: pin 1 = transmit+, 2 = transmit-, 3 = receive+, 6 = receive- ,
other pins not used.

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Switches:Up-Link: MDI-X (Media Dependent Interface-Crossover)
manual slide switch, converts RJ-45 port from a regular (=) user
segment port to a crossover (X) up-link port for on-off connection to a backbone
or another cascaded hub.
Packaging:
Enclosure: Rugged, high strength steel enclosure.
Suitable for vertical or horizontal mounting.
Recessed LEDs to avoid damage.
Dimensions:
H40A: 4.4in x 2.9in x 0.75in (11.0cm x 7.4cm x 1.9cm)
H50: 4.8in x 3.3in x 0.75in (12.2cm x 8.4cm x 1.9cm )
H80A: 4.4in x 5.0in x 0.75in (11.2cm x 12.7cm x 1.9cm )
H90: 4.4in x 5.0in x 0.75in (11.2cm x 12.7cm x 1.9cm )
Weight: H40A and H50:13oz (370gr); H80A and H90:1.0lbs (450gr);
Power Supply: 1.0lbs (455gr)
Cooling method:
Convection
Agency Approvals:
115v 60 Hz Power Supply is UL Listed, CSA certified.
230v 50 Hz Power Supply is same, also GS approved.
Emissions: Meets FCC Part 15 Class A and B, VDE Class B
Warranty:
Three years (see also Appendix A) Made in USA

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1.2 Ordering Information
Magnum Personal Hubs
MODEL DESCRIPTION
Magnum H40A-d Personal Hub with four standard RJ- 45 ports,
one with up-link switch, plus one AUI port, external 115 vac
60 Hz power supply.
Magnum H40A-i Same as H40A-d, but with external 230 vac
50 Hz power supply.
MagnumH50-d Personal Hub with four standard RJ- 45 ports,
plus one switched RJ-45 up- link port, external 115 vac 60 Hz
power supply.
Magnum H50-i Same as H50-d except with external 230 vac
50 Hz power supply.
Magnum H80A-d Personal Hub with eight standard RJ- 45 ports,
one with up-link switch, plus one AUI port, external 115 vac
60 Hz power supply.
Magnum H80A-i Same as H80A-d, but with external 230 vac
50 Hz power supply.
Magnum H90-d Personal Hub with eight standard RJ- 45 ports,
plus one switched RJ-45 up-link port, external 115 vac 60 Hz
power supply.
Magnum H90-i Same as H90-d except with external 230 vac
50 Hz power supply.
GarrettCom, Inc. reserves the right to change specifications, performance characteristics
and/or model offerings without notice.

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2.0 INTRODUCTION
This section describes the Magnum Personal Hubs, including
appearance, features and possible applications.
2.1 Inspecting the Package and Product
Examine the shipping container for obvious damage prior to installing
this product; notify the carrier of any damage which you believe occurred during
shipment or delivery. Inspect the contents of this package for any signs of damage
and ensure that the items listed below are included.
This package should contain:
1 Magnum Personal Hub
1 External Power Supply, either 115v 60 Hz or 230v 50 Hz
1 Velcro® Tape section, approximately 3 inches in length
1UserGuide
1 Product Registration Card
Remove the Magnum Personal Hub from the shipping container. Be sure
to keep the shipping container should you need to ship the unit at a later date. To
validate the product warranty please complete and return the enclosed Product
Registration Card to GarrettCom, Inc. as soon as possible.
In the event there are items missing or damaged, contact your supplier. If
you need to return the unit, use the original shipping container if possible. Refer to
Section 5, Troubleshooting, for specific return procedures.

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2.2 Product Description
The Magnum Personal Hub is a five or nine-port workplace hub in a very
compact package. It is simple to install and use in an office or lab environment,
requiring no special rack cabinets or wiring closet apparatus. Personal Hubs are
standard physical layer Ethernet products and operate independently of all
software.
Personal Hubs provide a simple and inexpensive solution for networking
a personal multi-system office using 10BASE-T twisted pair cabling. They can
expand a "power user’s" existing single-network-port outlet to provide up to eight
extra ports in the immediate office or lab area.
Personal Hubs are also well suited for small- to-medium-size office or lab
environments (up to eight persons) that need an independent Ethernet network.
They operate as self-sufficient units to provide 10BASE-T Ethernet connectivity
for local users and devices. Small independent networks built using Personal Hubs
are easily expanded by adding hubs of equal or greater capacity via cascaded
connections using the Up-Link switched port feature. The AUI port of the H40A
and H80A provide backbone connectivity if required.
The Personal Hub's small size make them very useful for demonstration
situations in conference rooms and in exhibitions where a temporary network or
network expansion is needed. They are handy as a piece of test equipment that can
be easily inserted into a network to provide a test port, and then removed after the
testing is done. Personal Hubs take up minimal space, use minimal power, and are
rugged enough to be carried in a coat pocket for possible emergencies.
10BASE-T Ports
Existing
Network Port Magnum H50
Personal Hub

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Personal Hubs fit easily into the workplace environment. They are
versatile enough to be table-top, shelf or wall-mounted (refer to Section 3 for
installation procedure). All of the wiring connectors are in the same plane so that
wiring space is neat and minimal.
The Personal Hub's RJ-45 ports support connection of up to four (H40A),
five (H50), eight (H80A) or nine (H90) workstations or other network devices over
full length 10BASE-T cable segments. Personal Hubs operate in compliance with
the IEEE 802.3 specification for repeater functionality to perform signal
amplification, re-timing of data packets, and regeneration of preamble bits for each
packet received. Consistent with IEEE 802.3 specifications, Personal Hubs will
detect collisions, extend collision fragments, and automatically partition and re-
connect individual ports in order to keep problems on one segment from causing
downtime elsewhere on the network.
Personal Hubs include LINK and RX LEDs, located on top of the unit
above each RJ-45 port, and one LED for power located at the rear near the external
power supply connection. The location of the LEDs makes it easy to associate the
status LEDs with the corresponding network port.
Each Personal Hubs are supplied one of two external power supply types;
one for AC power input of 115 vac 60 Hz, and one for 230 vac 50 Hz. (Refer to
Sections 1.1 and 3.0 for detailed information concerning the external power
supply.)

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MagnumPersonal Hubs: H40A, H80A, H50, H90
2.3 Features and Benefits
■
■■
■Interconnect to an Existing Ethernet Network
Personal Hubs provide a manual Up-Link switch that allows one RJ-45 port to be
to connect into an existing Ethernet environment (such as the central hub for the
building or area) via 10BASE-T wiring.
1 - RJ-45
t
4 - Port LEDs
2 - Switchable up-link
t
5 - Power
jk
3 - Up-link
it h
A - AUI port
H90 1
2
4
3
5
H50
3
1
45
2
H80
A
1
A
4
3
5
2
H40A 3
1
45
A
2
AUI portPower jack Power jack AUI port
Rear view - Magnum H40A Rear view -Magnum H80A
Rear view - Magnum H50 Rear view -Magnum H90
Switchable
up-link port Power jack Power jack
Switchable
up-link port Up-link
switch

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■
■■
■Inter-operable with other Ethernet Devices
Personal Hubs are completely inter-operable with other Ethernet-compliant
network devices. Each is fully compliant with IEEE 802.3 specifications for 10
Mbps CSMA/CD operation. This allows Personal Hubs to be integrated within any
standard Ethernet network and to operate with standard software.
■
■■
■Installation Versatility
Personal Hubs are simple and easy to install in most any office or lab location. The
tiny package is very unobtrusive and is typically mounted with Velcro.
■
■■
■Robust Network Operations
Personal Hubs use the "star" network topology and have automatic per-port
partitioning and re-connection. A fault on one segment is isolated from
the rest of the network, avoiding most network downtime.
■
■■
■LEDs Simplify Network Installation and Maintenance
Personal Hubs are equipped with a full complement of LEDs to provide status
about basic network activity. LINK LEDs for each port offer a very simple way for
operational connections of each 10BASE-T segment to be verified.
■
■■
■Low cost, stand-alone 10BASE-T connectivity
Operating in a stand-alone environment as a self-sufficient device, Personal Hubs
offer a very low cost method of providing small workgroups access to a variety of
Ethernet networking services such as file sharing, E-Mail, printer sharing, and
other computer information.
■
■■
■High Quality
Personal Hubs have a rugged steel case and are compliant with rigid Class CE
emission standards, making them suitable for commercial and home offices.

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2.4 Applications
Expanding from one to multiple ports at an existing site is easy, and
requires no modification to typical building wiring. The installer simply plugs the
existing networked device's network cable segment into one of the Personal Hub’s
front RJ-45 ports. The Up-Link port (switch set to X) connects via 10BASE-T
cabling to the existing network outlet. (The H40A and H80A also allow backbone
connection via the rear-mounted AUI port. A mini-transceiver may be connected
to this port to provide connectivity to any standard Ethernet media type.) The unit
is powered by plugging the external power supply into an AC power receptacle,
and connecting the DC power cord into the back of the Personal Hub. In minutes,
up to eight (H80A and H90) additional ports are available for networked devices.
Personal Hubs may also be used as a stand-alone network for a personal
multi-user system such as shown to the right. Up to nine (H90) user ports are
available for 10BASE-T connection, and full-length Ethernet segments are
supported on all segments. In this application, the up-link switch is in the straight-
through (=) position so that the switchable port is a user port, not an up-link to
another hub.
Personal Workgroup connected
via front RJ-45 ports
Existing
network port.
Switchable up-link
port (set to “X”)
Personal Workgroup connected
via front RJ-45 ports
Switchable up-link
port (set to “=”)
Additional user connected
via switchable up-link port

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3.0 Installation
The installation
of a Personal Hub is a very
simple procedure. Locate
an AC receptacle that is
within six feet (2 meters)
of the intended hub
location and plug in the external power supply (supplied with unit). The small DC
power cord from the power supply plugs into the rear power jack of the Personal
Hub. When power is applied the green PWR LED will be illuminated.
The external power supply unit supplied is one of two types; one for AC
power input of 115 vac 60 Hz, and one for 230 vac 50 Hz. Examine the power
supply to make sure the type is the right type for your AC power system. The 115
vac unit has a small transformer integral with a convenience power outlet plug.
The 230 vac unit has a small transformer integral with an IEC-type power plug for
a user-supplied AC power cord with a convenience power outlet plug. Both types
include a lightweight DC power cord for connection to the power jack on the
Personal Hub unit.
3.1 Table-Top or Shelf Mounting
Personal Hubs are easily mounted on a table-top or shelf, and have four
rubber feet to provide stability without scratching finished surfaces. A piece of
Velcro may be used to add additional stability if desired. When properly installed,
the top-view LED status indicators will be in plain view and easy to read.
The rugged steel case of the Personal Hub will protect it from accidental
damage in an office or lab workplace setting. Keep an open area around the unit so
that convection cooling can occur while the unit is in operation.
Magnum H80
Personal Hub
External
power supply
Personal Hub power
connection - (H80A shown)

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3.2 Wall (or Vertical Surface) Mounting
A piece of Velcro mounting tape is supplied with the unit, and may be
used to mount a Personal Hub in a vertical position. Adhere one side of the Velcro
on the bottom of the hub between the rubber feet. Adhere the other side of the
Velcro to the desired vertical mounting location. Typical mounting locations
include an office wall surface, the side of a server unit cabinet or the back of a
desk.
As an alternative, small brackets may also be used for mounting the
Personal Hub. The metal screws in each side of the Personal Hub’s case may be
used to attach the brackets. Use of the optional brackets permits the Personal Hub
to be mounted in almost any desired orientation or position.
Personal Hub, Velcro mounting
vertical mounting surface
Velcro strip
Personal Hub
PWR
PORT 9 LINK
UP LINK
Magnum H90
Personal HubT
M
RX
LINK
PORT 1 2 3 4 5 6 7 8
Personal Hub, optional
mounting brackets
Proper mounting
bracket attachment

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3.3 Twisted Pair Connections
1. Using standard
10BASE-T media, insert the
one end of the network cable
into one of the RJ-45 ports
on the Personal Hub. Even
though the hub's ports are of
the shielded type, they will
accept and operate properly
with shielded and unshielded type RJ-45 twisted pair wiring.
2. Connect the other end of twisted pair segment to the desired
workstation or user device. The port’s LINK LED will be lit when the connection
is made on both ends of the segment and DC power is present, i.e., when the
segment circuit is established and is ready to use.
3. For information on using the up-link port, refer to Section 3.5.
3.4 AUI Connection (Models H40A and H80A only)
Using the steps below
as a guide, attach a new or
existing 10BASE5 ThickNet
drop-cable directly to the AUI
connector on the rear of the
Magnum H40A or H80A.
1. Plug the male end of
the cable into the female AUI connector on the Personal Hub.
2. Engage the AUI connector slide lock to insure maximum connectivity.
3. Connect the opposite end of the cable into a network AUI port. (This
could be a network backbone transceiver, a hub or fan-out with an AUI port, or an
AUI Port Module in a concentrator.)
Twisted pair connections -
Magnum Personal Hub
H80
Hub
Magnum H80
Personal Hub
AUI connection -
Magnum H40A and H80A

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The AUI port may also used for connecting to other Ethernet devices
using standard AUI cabling. In this type of situation, it is important to consider the
AUI segment length to the attached device, including any cascading.
The maximum transmission distance between a backbone transceiver and
the AUI port of the Personal Hub will vary. According to Ethernet standards,
when an AUI cable is used to connect the Personal Hub directly to a backbone
transceiver, the maximum AUI segment length of 50m (165 ft.) is allowed. If the
Personal Hub is connected to a transceiver that has been cascaded from another
transceiver, the maximum AUI segment length is reduced by 6 meters (20 feet), for
every additional transceiver device cascaded from the original backbone
transceiver tap..
The AUI connector of the Personal Hub supports standard IEEE signals,
which are summarized in Table 3.4
Table 3.4 AUI Pin Assignments
Pin Function Pin Function
1 Control In Circuit Shield 10 Data Out Circuit B
2 Control In Circuit A 11 Data Out Circuit Shield
3 Data Out Circuit A 12 Data In Circuit B
4 Data In Circuit Shield 13 Voltage Plus (+)
5 Data In Circuit A 14 Voltage Shield
6 Voltage Common 15 Control Out Circuit B
7 Control Out Circuit A SHELL Protective Ground
8 Control Out Circuit Shield (conductive shell)
9 Control In Circuit B
NOTES: 1) Voltage Plus (pin #13) and Voltage Common
(pin # 6) use a single twisted pair in the AUI cable.
2) Pins 4, 8, 11 and 14 may be connected to pin #1.
3.5 Switchable Up-Link Feature
Each Personal
Hub is equipped with
one switchable up-link
port, which eliminates
the need for a special
cross-over cable when
cascading to hub or
concentrator. This port
user (==) uplink (X)
Personal Hub up-link switch
(H80A shown)
H80
Hub
Up-link
switch

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is either the rear RJ-45 port (H50 and H90) or the right-most front RJ-45 port
(H40A and H80A). This switch is used to select either a normal 10BASE-T
connection to a user device (switch in the "==" position) or a 10BASE-T network
up-link connection to another hub or concentrator (switch in the "X" position).
NOTE: When the switchable port is connected for up-link but the
switch is set to the == position, the up-link segment is
inoperative and full bandwidth is available locally.
3.6 Cascading Personal Hubs with the Up-Link Port
Personal Hubs may be cascaded in order to expand networks. The
switchable up-link port (set to the X position) is normally used to connect the
Personal Hub to any port of another hub. Also, the Models H40A and H80A may
be connected to a backbone via the rear AUI port. With the addition of a mini-
transceiver, the AUI port may be used to connect to any standard Ethernet media.
Since each Personal Hub provides full repeater functionality, cascaded units can
operate together even though there may be a full segment of distance between
them.
NOTE: Based on the "four repeater rule" defined by Ethernet standards,
there may normally be a maximum of four units in any one chain between any
two users.
Personal Hubs may also be cascaded with other Magnum Hubs (such as
Magnum 1000 Workgroup Hubs and Magnum 3000 Stackable Hubs and
Concentrators) as well as with Ethernet hubs from other manufacturers.
Switchable Up-Link
Port (set to X)
User Segments
User Segments
Switchable Up-Link
Port (set to X)
User Segments
User Segments
Switchable Up-Link
Port (set to X)
Cascaded Personal Hubs: Full Repeater Functionality

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4.0 OPERATION
This section details the various operational features of Magnum Personal
Hubs, including a description of the LED indicators. All Personal Hubs are fully
compliant with the Ethernet Version 2/IEEE 802.3 Repeater Specification for
CSMA/CD 10Mbps operation and will function accordingly.
4.1 Functional Operation, Use of LED Indicators
Power On (PWR) LED: Illuminates GREEN to show functional DC power.
Link Status (LINK) LED (per port): Illuminates GREEN when proper
connectivity on the 10BASE-T network segment is established. Each LINK LED
will turn off independently if connectivity or power is lost on the port’s twisted pair
segment.
Note: When the switchable port is wired for up-link to another hub, the
LINK LED will normally be on when the up-link switch is set to the X position.
With the up-link switch off ( == position), the LINK LED is off as the up-link is
disabled. This permits local operation of the Personal Hub with full
bandwidth.
Receive Packets (RX) LED (per port): Illuminates intermittently in GREEN to
indicate that data packets are being received from the segment. This provides a
visual indication of network activity for re-assurance of normal operation, and is
also useful in troubleshooting.
Note: Blinking indicates activity. The rate at which the RX LED blinks is
associated with the data transfer intensity on some models, and is a fixed
rate on other models.
Partitioning and Re-connection: Personal Hubs will automatically partition a
port when 32 consecutive collisions occur or after 6.5 ms of continuous
transmission. Network integrity is checked every 800 ms and segment re-
connection occurs after one 512-bit packet is transmitted without an error.
Preamble Regeneration: Personal Hubs add bits to the preamble so that the output
packet contains a minimum 64-bit preamble per the Ethernet standard.
Collisions: When carrier is detected simultaneously on multiple ports, a jam
pattern is generated on each port to create a collision condition. When a collision
signal from one port is detected, it generates a jam pattern to other ports.