Black Box LH8000A-M, LH8000A-C Installation And User Manual

© Copyright 2002. Black Box Corporation. All rights reserved.

1000 PARK DRIVE • LAWRENCE, PA 15055-1018 • 724-746-5500 • FAX [phone]

January 2002

LH8000A-M,

LH8000A-C

Dual-Speed Stackable Hub

Installation and User Guid

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BLACK BOX

Dual Speed Stackable Hub

Order toll-free in the U.S. 24 hours, 7 A.M. Monday to midnight Friday: 877-877-BBOX
FREE technical support, 24 hours a day, 7 days a week: Call 724-746-5500 or fax [phone]
Mail order: Black Box Corporation, 1000 Park Drive, Lawrence, PA 15055-1018
Web site: www.blackbox.com • E-mail: [e-mail]

Black Box Dual-Speed Stackable Hubs Installation and User Guide

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BLACK BOX

®

10/100 Dual-Speed Stackable Hubs

Installation and User Guide

Trademarks

UL is a registered trademark of Underwriters Laboratories
Ethernet is a trademark of Xerox Corporation
Velcro is a trademark of Velcro U.S.A.
UL is a registered trademark of Underwriters Laboratories

Important: The LH8000A Dual-Speed 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 an LH8000A,
consult Section 5, Troubleshooting, of this User Guide.

©2002 Black Box Corporation
84-00067 Rev. B 1/02

Printed in the United States of America.

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Contacting Black Box Corporation

Please use the mailing address, phone and fax numbers listed below.

Black Box Corporation

1000 Park Drive

Lawrence, PA 15055

Phone [phone]

Fax [phone]

email: [e-mail]

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FEDERAL COMMUNICATIONS COMMISSION

AND

CANADIAN DEPARTMENT OF COMMUNICATIONS

RADIO FREQUENCY INTERFERENCE STATEMENTS

This equipment generates, uses, and can radiate radio 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 B of Part 15 of FCC
rules, which are designed to provide reasonable protection against such
interference when the equipment is 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 necessary to correct the interference.

Changes or modifications not expressly approved by the party responsible for
compliance could void the user’s authority to operate the equipment.

This digital apparatus does not exceed the Class A limits for radio noise
emission from digital apparatus set out in the Radio Interference Regulation of
the Canadian Department of Communications.

Le présent appareil numérique n’émet pas de bruits radioélectriques dépassant
les limites applicables aux appareils numériques de la classe A prescrites dans le
Règlement sur le brouillage radioélectrique publié par le ministère des
Communications du Canada.

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Normas Oficiales Mexicanas (NOM)

Electrical Safety Statement

INSTRUCCIONES DE SEGURIDAD

1. Todas las instrucciones de seguridad y operación deberán ser leídas antes
de que el aparato eléctrico sea operado.

2. Las instrucciones de seguridad y operación deberán ser guardadas para
referencia futura.

3. Todas las advertencias en el aparato eléctrico y en sus instrucciones de
operación deben ser respetadas.

4. Todas las instrucciones de operación y uso deben ser seguidas.

5. El aparato eléctrico no deberá ser usado cerca del agua—por ejemplo,
cerca de la tina de baño, lavabo, sótano mojado o cerca de una alberca,
etc.

6. El aparato eléctrico debe ser usado únicamente con carritos o pedestales
que sean recomendados por el fabricante.

7. El aparato eléctrico debe ser montado a la pared o al techo sólo como sea
recomendado por el fabricante.

8. Servicio—El usuario no debe intentar dar servicio al equipo eléctrico más
allá a lo descrito en las instrucciones de operación. Todo otro servicio
deberá ser referido a personal de servicio calificado.

9. El aparato eléctrico debe ser situado de tal manera que su posición no
interfiera su uso. La colocación del aparato eléctrico sobre una cama,
sofá, alfombra o superficie similar puede bloquea la ventilación, no se
debe colocar en libreros o gabinetes que impidan el flujo de aire por los
orificios de ventilación.

10. El equipo eléctrico deber ser situado fuera del alcance de fuentes de calor
como radiadores, registros de calor, estufas u otros aparatos (incluyendo
amplificadores) que producen calor.

11. El aparato eléctrico deberá ser connectado a una fuente de poder sólo del
tipo descrito en el instructivo de operación, o como se indique en el
aparato.

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12. Precaución debe ser tomada de tal manera que la tierra fisica y la
polarización del equipo no sea eliminada.

13. Los cables de la fuente de poder deben ser guiados de tal manera que no
sean pisados ni pellizcados por objetos colocados sobre o contra ellos,
poniendo particular atención a los contactos y receptáculos donde salen
del aparato.

14. El equipo eléctrico debe ser limpiado únicamente de acuerdo a las
recomendaciones del fabricante.

15. En caso de existir, una antena externa deberá ser localizada lejos de las
lineas de energia.

16. El cable de corriente deberá ser desconectado del cuando el equipo no sea
usado por un largo periodo de tiempo.

17. Cuidado debe ser tomado de tal manera que objectos liquidos no sean
derramados sobre la cubierta u orificios de ventilación.

18. Servicio por personal calificado deberá ser provisto cuando:

A: El cable de poder o el contacto ha sido dañado; u

B: Objectos han caído o líquido ha sido derramado dentro del aparato; o

C: El aparato ha sido expuesto a la lluvia; o

D: El aparato parece no operar normalmente o muestra un cambio en su

desempeño; o

E: El aparato ha sido tirado o su cubierta ha sido dañada.

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Certification Notice for

Equipment Used in Canada

The Canadian Department of Communications label identifies certified
equipment. This certification means that the equipment meets certain
telecommunications-network protective, operation, and safety requirements. The
Department does not guarantee the equipment will operate to the user’s
satisfaction.

Before installing this equipment, users should ensure that it is permissible to be
connected to the facilities of the local telecommunications company. The
equipment must also be installed using an acceptable method of connection. In
some cases, the company’s inside wiring associated with a single-line individual
service may be extended by means of a certified connector assembly (extension
cord). The customer should be aware that compliance with the above conditions
may not prevent degradation of service in some situations.

Repairs to certified equipment should be made by an authorized Canadian
maintenance facility—in this case, your supplier. Any repairs or alterations
made by the user to this equipment, or equipment malfunctions, may give the
telecommunications company cause to request the user to disconnect the
equipment.

Users should ensure for their own protection that the electrical ground
connections of the power utility, telephone lines, and internal metallic water
pipe system, if present, are connected together. This precaution may be
particularly important in rural areas.

CAUTION:

Users should not attempt to make such connections
themselves, but should contact the appropriate electric
inspection authority, or electrician, as appropriate.

The LOAD NUMBER (LN) assigned to each terminal device denotes the
percentage of the total load to be connected to a telephone loop which is used by
the device, to prevent overloading. The termination on a loop may consist of any
combination of devices, subject only to the requirement that the total of the load
numbers of all the devices does not exceed 100.

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TABLE OF CONTENTS PAGE

1.0

SPECIFICATIONS ........................................................................................ 1

1.1 Technical Specifications ...................................................................................... 1

2.0 INTRODUCTION .......................................................................................... 3

2.1 Inspecting the Package and Product .................................................................... 3

2.2 Product Description ............................................................................................ 4

2.2.1 Dual-Speed Hub Chassis ......................................................................... 6

2.2.2 10 / 100 Speed Auto-sensing ................................................................... 6

2.3 Stacking LH8000As ........................................................................................... 7

2.4 Bridge Module between the 10Mb and 100Mb Domains .................................... 8

2.5 Up-link Switch on Port # 8 for Cascading ........................................................... 8

2.6 Features and Benefits .......................................................................................... 9

2.7 Applications ...................................................................................................... 10

3.0 INSTALLATION ......................................................................................... 12

3.1 Locating the Dual-Speed Hubs .......................................................................... 12

3.1.1 Table-Top or Shelf Mounting ................................................................ 12

3.1.2 Wall (or Vertical Surface) Mounting ..................................................... 12

3.2 Connecting Ethernet Media ............................................................................. 13

3.2.1 Connecting TP (RJ-45, CAT3 or CAT5 unshielded or shielded

) ...................... 13

3.2.2 100Mbps Collision Domain Diameter, Cable dimension and PDV calc. ....... 13

3.2.3 Connecting to NICs which support Auto-Negotiation ............................ 17

3.3 Powering the Dual-Speed Hub ......................................................................... 17

4.0 OPERATION ............................................................................................... 18

4.1 Dual-Speed Functionality .................................................................................. 18

4.2 Auto-negotiation and speed-sensing ................................................................. 20

4.3 LEDs ................................................................................................................ 20

4.4 Up-link Switch .................................................................................................. 20

5.0 TROUBLESHOOTING ............................................................................... 21

5.1 Before Calling for Assistance ............................................................................ 21

5.2 When Calling for Assistance ............................................................................. 22

5.3 Shipping and Packaging Information ............................................................... 22

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1.0 SPECIFICATIONS

1.1 Technical Specifications

100 or 10 Mbps per port, auto-sensing for speed. LH8000A hubs support

two traffic domains, one at 100Mbps and one at 10Mbps, have eight RJ-45
ports, and are stackable up to 4 units high operating as one repeater.

Performance

When a port is operating at 100Mbps:

Data Rate: 100 Mb/s
PDV (Path Delay Value) : 80BT, exceeds Class II
When a port is operating at 10Mbps :
Data Rate: 10 Mbps

Partitioning: Enforced after 63 consecutive collisions
Auto-reconnect: Occurs after one packet of error-free reception

Network Standards

100Mb: Ethernet IEEE 802.3u , 100BASE-TX
10Mb: Ethernet IEEE 802.3, 10BASE-T
Auto-sensing for speed: IEEE 802.3u

Packet-Processing Between Domains (internal 10/100 switch or bridge)
Filtering and Forwarding Rate from 100Mbps ports: 148,800 pps max

Filtering and Forwarding Rate from 10Mbps ports: 14,880 pps max.
Processing type : Store and Forward

Auto-learning : 8K address table, shared for both traffic domains
Packet buffers : 2MB,dynamically allocated & shared on both domains
Latency (not including packet time) : 100 to 10Mb : 5μs
10 to 100Mb : 5μs
CPU Type : State Machine

Maximum Ethernet Segment (or Domain) Lengths
10BASE-T (Unshielded twisted pair) - 100 m (328 ft)

100BASE-TX (CAT 5 UTP) - 100 m (328 ft)

Operating Environment

Ambient Temperature: 32ºF to 122ºF (0ºC to 50ºC)

Storage Temperature: -20ºC to 60ºC
Ambient Relative Humidity: 10% to 95% (non-condensing)

Power Supply (Internal

)

AC Power connector : IEC-type, male recessed, rear of chassis

Power Input Voltage : 90 to 260 VAC (auto ranging)
Power Input Frequency : 47-63 Hz

Power Consumption : 20 watts max.

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(1.1 Technical Specifications, continued)

Network Cable Connectors - for the eight RJ-45 shielded female ports per hub

100Mbps : Category 5 UTP/STP
10Mbps : Category 3, 4, 5 UTP (Note: speed-sensing does not sense cable
type)

Stacking Cable - stacking may be up to four LH8000A hubs, or 32 ports

A stacking cable with 50-pin “SCSI” male connectors, shielded, 9 inches (23
cm) long, is included with each LH8000A-C Dual-Speed add-on unit.

Switch, Manual

UP-LINK : MDI-X thumb-operated slide switch, converts RJ-45 port #8 from a
regular (=position) user segment port to a crossover (X position) up-link port for
On/Off connection to a central hub or another cascaded hub. The up-link port
#8 is auto-sensing for speed, and the up-link works the same at 10Mb or 100Mb.

Packaging
Enclosure: High strength metal. Metal mounting brackets included.
Suitable for wiring closet shelf, wall or desktop mounting.
Dimensions: 9.75 in D x 8.5 in. W x 1.4 in. H ( 25cm x 22cm x 3.5cm)
Weight: 2.5 lb. ( 1.15 Kg)
Cooling method: Fan cooled, internal @ 9 cfm

LED Indicators
PWR : Steady ON when power applied
BR : Bridge Module Indicator, ON when 10/100 bridge module is installed
(Model LH8000A-M), OFF when no bridge module is inside
(LH8000A-C)
COL : Collision LEDs, one each for 100Mbps and 10Mbps speed domains
ACT : Common packet activity indicator, one for each traffic domain
100 (per port): Steady ON when speed is 100Mbps , OFF when speed is 10Mbps
, flashing when auto-negotiating or when not connected (no LINK)
LK (per port): Steady ON when twisted-pair link is operational
RX (per port): Activity, flashing when port is receiving data

Agency Approvals
UL Listed (UL 1950), cUL, CE

Emissions: meets FCC Part 15, Class A
Made in USA

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2.0 INTRODUCTION

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 LH8000A-C or LH8000A-M Dual-Speed Hub Unit
1 Stacking Cable, Model LH8000A-C

add-on (no bridge inside) units only

1 Set of metal clips and screws for wall-mounting
1 AC Power Cord (U.S. and other 115 vac locations only)
1 Installation and User Guide

Remove the LH8000A Dual-Speed 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 Black Box 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. Refer to Chapter 5, Troubleshooting, for
specific return procedures.

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2.2 Product Description - General

LH8000A Dual-Speed hubs have eight RJ-45 ports, each 10/100Mbps auto-sensing.
Each port can independently identify (via IEEE 802.3u auto-sensing) and accept either
100Mbps or 10Mbps Ethernet signals, adapting to match the best speed of the connected
device. There are two internal traffic domains in LH8000A hubs, one for the 100Mb traffic and
one for the 10Mbps traffic. The 100Mbps users share the 100Mb domain’s bandwidth and the
10Mbps users share the 10Mbps domain’s bandwidth.

Any LH8000A port can connect into either the 100 or the 10Mbps traffic domain,
and can also change from one traffic domain to the other at any time without affecting the
speed of other ports. The automatic per-port speed-sensing is continuous, allowing the
connected devices to change speed at any time without impairing the operation of the other
ports and connected devices.

Figure 2.2.1 : LH8000A-C is functionally both a 10Mb and a 100Mb hub in one

As LH8000A Dual-Speed units are stacked, the two shared traffic domains
automatically expand to support all of the ports in the stack. Any combination of 10Mbps and
100Mbps ports, up to the maximum of 32 ports (4 units) in one stack, can be in use at any time.

One LH8000A Model, the LH8000A-M, includes an internal bridge or switch module
which interconnects the 10Mbps and the 100Mbps traffic domains. This enables all users on an
LH8000A-M hub or an LH8000A stack, whether 100Mbps or 10Mbps , to talk to each other.
The internal switch of the LH8000A-M filters and selectively forwards packets between the
10Mbps and the 100Mbps domains, maintaining peak performance in each domain unaffected
by local traffic in the other domain. The internal bridge is self-learning, with large address table
capacity for up to 8K node addresses. As networked nodes are added or removed or move from
one speed domain to the other, the LH8000A’s internal switch automatically keeps track.

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Magnum
8000E

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Stackable
Hub

GARRETT

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10Mb Hub 100Mb Hub

LH8000A-C

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2.2 Product Description - General (continued)

Figure 2.2.2 : LH8000A-M is an LH8000A-C with a built-in for 10/100 bridge module

Only one LH8000A-M unit is needed to support a stack. Additional 8-port units of
the LH8000A-C “add-on” hubs . . . units that do not have the bridge module inside, and which
cost less accordingly . . . can be added to the stack, up to the 4-unit stack maximum. In a stack,
the LH8000A-M unit (illustrated below as the bottom unit) can be in any stack position.

Figure 2.2.3 : Stack of LH8000As, 3 @ LH8000AA’s and 1 @ LH8000A-M

LH8000A-C units can also be used without an LH8000A-M, whereupon they will
function as dual-speed stackable hubs. This could be desired if there is an external non-auto­sensing switch available to interconnect the two speed domains, or if only 100Mbps devices
are connected and the 10Mbps domain is unused (or vice-versa), or if dual-speed operation
with two unconnected and uncoordinated domains is needed for the application.

Each LH8000A has its own internal power supply , and is easily added to an existing
10 or 100Mbps network. LH8000As are suitable for wiring closet shelf, table-top or vertical
mounting.

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BLACK BOX

Dual Speed Stackable Hub

[phone]

LH8000A-C

LH8000A-C

LH8000A-M

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2.2.1 Dual-Speed Hub Chassis

The LH8000A chassis houses one main PC board, a bridge module daughter- board
in the Model LH8000A-M, and an internal power supply unit. The front side of the chassis has
eight RJ-45 twisted-pair ports and one cascading (UP-LINK) switch for Port 8 on the right.

LEDs to indicate operating status are on the left front side. There are power (PWR)
and bridge-inside (BR)
indicators for the unit.
There are activity (ACT)
and collision (COL)
indicators for each of the
10Mbps and 100M b domains, LH8000A Dual-Speed Hub

set unto a “square” arrangement, for visual indication of the operating status of each domain.
And there are link (LK), receive (RX) and speed (100) indicators for each port. (See Section

1.1 “Specifications” for a technical description of the LEDs). The unit has a cooling fan on the
bottom left corner which sends warm air out away from the unit to the rear. Stacking cables
connect in the rear (see Section 2.3 for stacking information).

The AC power cord connector, a universal recessed-male IEC type, is in the left
rear of the chassis. The internal power supply is auto-ranging for any AC power input of 115 ­230 vac, 50 - 60 Hz. (An internal DC power supply is optional).

2.2.2 10 / 100 Speed Auto-sensing

All eight RJ-45 twisted pair ports support auto-sensing for speed, independent of the
other ports. Speed-sensing is performed by the LH8000As electronics in accordance with the
standards of the IEEE 802.3u auto-negotiation standard. If the connected device or node
indicates that it is capable of 100Mbps speed, then operation on that port will be at 100Mbps .
If the connected device does not positively indicate that it is capable of 100Mbps speed, then
the operation on that LH8000A port will be at 10Mbps . Of course, the hubs’ auto-negotiation
technique is only for 10 / 100 speed, and does not provide for any full-duplex operation.

When a port is connected and LINK is present, the speed on that port that has been
sensed by the LH8000A hub will be indicated by the ‘100’ LED for that port. The ‘100’ LED is
ON when 100Mbps speed is sensed, and is OFF when 10Mbps speed is in use. When a port is
not connected, the ‘100’ LED corresponding to that port will be blinking to indicate that it is
trying to auto-negotiate. (See section 4.3 for operation of the LED’s).

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Dual Speed Stackable Hub

[phone]

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2.3 Stacking LH8000As

Up to four LH8000As can be stacked to operate as one 10/100 dual-speed repeater
with up to 32 dual-speed ports. Normally, one LH8000A-M hub per stack is needed to provide
a switched
interconnection between
the two separate
100Mbps and 10Mbps
traffic domains in the
stack. Additional
stacked units are
normally Model
LH8000A-C “add-on”
units, which cost less.

Figure 2.3 : LH8000As stacked. Cables connect between “Out” and “In” Ports

The LH8000A-M models with the bridge module inside look the same as the
LH8000A-C units (no bridge inside) from the outside. The “BR” LED on the front will light up
when power is applied to indicate that an LH8000A is a -M (bridge inside) model. (The “BR”
LED will be off if the unit is a Model LH8000A-C). The LH8000A-M models cannot be
stacked together, as their internal bridges would not be able to function properly when more
than one is present. Use LH8000A-M models un-stacked, or with only 1 Model LH8000A-M in
an LH8000A stack. See Section 2.7, Example 3.

When stacking LH8000As, please make sure to use only the shielded 9-inch long
stacking cable provided with each LH8000A-C unit. The cable length is designed to provide
proper operation of up to four LH8000A units in a stack, and longer cables or unshielded cables
are not permitted as they will not operate properly at 100Mbps speeds.

The 9-inch length is enough to provide for side-by-side stacking. This can be
convenient when locating the LH8000As in a rack, for example, as two LH8000As will fit side­by-side on a tray in a standard 19” rack space.

When connecting LH8000As in a stack, use the stacking cable to connect the “Out”
stacking port from one LH8000A unit to the “In” stacking port of the other. Push in the cable
connectors until they snap in firmly. Also, leave space in the left-rear area for the exhaust of
the internal cooling fan in each LH8000A unit. See Figure 2.3 above.

OUT IN

OUT IN

OUT IN

OUT IN

FAN EXHAUST

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2.4 Bridge Module between the 10Mbps and 100Mbps

Domains

Figure 2.4 : Internal view of

LH8000A-M with bridge

module installed

An LH8000A-M
contains a factory-installed bridge module to interconnect the two traffic domains, filtering and
selectively forwarding packets to allow only necessary packets to cross between the domains.
This enables all of the users and nodes connected into either domain, whether 100Mbps or
10Mbps , to talk to each other, and it keeps local traffic on one domain from consuming any of
the bandwidth of the other domain.

The bridge operates in the store-and-forward mode, which filters out bad packets and
maintains optimum performance in both domains. Packet forwarding delay is only 5μs (plus
packet time), much less than traditional store-and-forward bridge products, enabling the
LH8000As to maintain high network performance. The bridge has 8K node address capacity,
suitable for use in large networks. Addresses are self-learning so that filtering / forwarding of
10Mb and of 100Mb packets is maintained correctly even when users move their connection, or
change speed, or power down.

The LH8000A-M’s bridge module is implemented as a daughter board. LH8000A
units have an LED on the front labeled ‘BR’ that will be ‘ON’ when the module is installed
internally. Power any LH8000A unit up and if the BR LED is ON, it is an LH8000A-M unit.

NOTE : Only one LH8000A-M (with a bridge module built-in) is allowed per
repeater stack. Thus, if the LH8000As in a stack have more than one BR
(bridge) LED ‘ON’, it is an illegal configuration.

2.5 Up-link Switch on Port 8 for Cascading

The unit has an up-link switch for Port # 8, located on the right-front side of the hub.
It enables the port’s cable to either connect to a user station ( = position) or to be cascaded to
another hub (X position). (See Section 4.4 for more details about up-link). Like all LH8000A
ports, Port # 8 is a dual-speed port which will sense the speed of the connected device. The up­link switch operates the same, whether Port # 8 is connected to either 100Mbps or 10Mbps
devices. When the up-link port is used to cascade two LH8000A hubs or stacks together, the
auto-sensing feature will cause the connecting link to operate at 100Mb speed.

2.6 Features and Benefits

Bridge Module

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 Supports 10 or 100Mb network connections on each of eight RJ-45 ports

LH8000A Dual-Speed 10 / 100 hubs combine two logical hubs . . . one at 10Mbps
and one at 100Mbps . . . in one physical box supporting two traffic domains. Each
port can operate at either 10 or 100Mbps , independently of the other ports.

 Auto-sensing for speed, 10 or 100Mb on each port

All ports support 10/100 auto-negotiation for speed, operating separately on each
port. Any mix of 10Mbps and 100Mbps users can be connected to the ports. Speed­sensing is continuous. Individual ports can change to 100Mbps or 10Mbps speed at
any time, adapting automatically to any changes in the connected device’s speed.
Speed-sensing complies with IEEE 802.3u, providing interoperability with other
products.

An internal switch connects the 10 and 100Mb domains on Model LH8000A-M
Model LH8000A-M has an internal switch for filtering / forwarding traffic between

the 10 and 100Mbps domains, allowing all connected devices to talk to each other.
Switching provides full bandwidth in each domain, unaffected by local traffic on the
other domain. One LH8000A-M per stack supports switching for all ports.

 Stackable for flexible expansion

LH8000As can be stacked up to four units high for 32 ports, each 10 / 100 dual
speed. As additional units are added in a stack, the 10 and 100Mb traffic domains are
expanded automatically to support the new ports at either 10 or 100Mbps speed.

 Installation is “Plug and Play”, Operation is Transparent to Software

The LH8000A-M operates as a hardware switch, only forwarding those packets from
each domain that are needed on the other domain. Internal address tables are self­learning, enabling users to change port connections or 10 / 100 domains without
affecting operations. The switch in the LH8000A-M will not affect any standard
software applications or SNMP network management platforms.

 Small Enclosure Enables Use in Offices and Labs

The compact packaging of LH8000As allows them to be installed in offices and labs,
or virtually any location within reach of a standard AC wall outlet. They comes in a
durable metal enclosure for table-top or wall-mounting. They have an internal auto­ranging power supply for use worldwide.

2.7 Applications

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Example 1 : An LH8000A-M serves a small office with mixed speed requirements. Some
users operate at 100Mbps , and some users and utility devices (such as print servers) run at
10Mbps . All share the same hub, and talk to each other via the bridge module inside. Any
node can change speed at any time without affecting network operation or impacting other
users.

Figure 2.7.1 : LH8000A-M connects combinations of 10Mbps and 100Mbps network

devices

Example 2 : Where there are existing 10Mb hubs and users, they can easily be cascaded into

any port of the LH8000A-M. This allows simple plug-and-play addition of 100Mbps ports to
an existing 10Mbps network without having to change it. Nodes that are capable of 100Mbps
speed can be moved to any LH8000A dual-speed port, and will automatically operate at the
higher speed. The dual-speed ports on the LH8000A-M can be used for adding 100Mbps users
or for accommodating existing high performance users. The 100Mb traffic does not use the
bandwidth of the
10Mbps domain, so
overall performance of
the network is
improved.

Figure 2.7.2 : An
LH8000A-M adds a
new 100Mbps
domain to an existing
10Mbps network

Router

100

Server

100

100

100100

Print Server

Users

10

1 2 3 4 5 6 7 8

COL

ACT

PWR

LK
RX

BR

UPLINK

1 2 3 4 5 6 7 8

100

Dual Speed Stackable Hub

(412) 746-550 0

BLACK BO X

Print Server

100

Router

10 Mb Hub

100

GARRETT

1 2 3 4 5 6 7 8 9 10 11 12

Users

100

100

100

Server

10

10

10

10

1 2 3 4 5 6 7 8

COL

ACT

PWR

LK
RX

BR

UPLINK

1 2 3 4 5 6 7 8

100

Dual Speed Stackable Hub

[phone]

BLACK BOX

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Example 3 :
For additional expansion, an LH8000A-M can be expanded by stacking LH8000A-C

“add-on” units. The additional stacked ports are all auto-sensing dual-speed, and can be used at
either 10Mbps or 100Mbps on a per-port basis.

The stacking cables connect the LH8000A units and carry the signals for both the
100Mbps and the 10Mbps domains. In a stack, all 10Mbps ports are together in a 10Mbps
traffic domain while all 100Mbps ports are similarly together on a separate 100Mbps traffic
domain. When one LH8000A-M unit with a bridge inside is present in a stack, its bridge will
support all of the ports in the stack and enable network traffic to move between the two stacked
domains.

An LH8000A stack operates as one dual-speed

repeater. A dual-speed repeater is
both a 10Mb hub and a 100Mb hub at the same time. This means that the 10Mbps traffic
domain obeys all of the rules of 10Mbps shared Ethernet networks (hop counts, cable types,
cable distances, etc.) and can be treated as one 10Mbps repeater accordingly. Separately, the
100Mbps traffic domain obeys all of the rules of 100Mbps Fast Ethernet shared networks (hop
counts, PDVs, cable types, cable distances, etc.) and can be treated as one 100Mb repeater.
Both traffic domains function within the same physical LH8000A hub or stack of hubs.

Figure 2.7.3 : Stack of

LH8000As operate as

one 10/100 dual-speed

repeater

When expanding an Ethernet or Fast Ethernet installation, the LH8000A Hubs are
ideally suited for connecting servers and stations that have (or may

have in the future ! ) mixed
speeds. Each traffic domain or segment has its own local traffic with the LH8000A-M
performing bridge-isolation of one domain from the other, filtering and selectively forwarding
10Mbps and 100Mbps packets between the two domains. This keeps the traffic between the
domains to a minimum and provides peak performance on both domains.

Print Server

100

Router

10 Mb Hub

100

GARRETT

1 2 3 4 5 6 7 8 9 10 11 12

Users

100

100

100

Server

10

10

10

10

1 2 3 4 5 6 7 8

COL

ACT

100 10

PWR

LK
RX

BR

100

UPLINK

1 2 3 4 5 6 7
8

1 2 3 4 5 6 7 8

COL

ACT

100 10

PWR

LK
RX

BR

100

1 2 3 4 5 6 7
8

1 2 3 4 5 6 7 8

COL

ACT

100 10

PWR

LK
RX

BR

100

1 2 3 4 5 6 7
8

1 2 3 4 5 6 7 8

COL

ACT

100 10

PWR

LK
RX

BR

100

1 2 3 4 5 6 7
8

UPLINK

UPLINK

UPLINK

Dual Speed Stackable Hub

[phone]

BLACK BOX

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3.0 INSTALLATION

This chapter provides instructions for installing the LH8000A hubs.

3.1 Locating the Dual-Speed Hubs

The location of an LH8000A Dual-Speed Hub is dependent on the physical layout of
the network. Typically the hub is placed where combinations of 10Mbps and 100Mbps
network devices need to be connected to communicate with each other. The compact size of
the unit allows it to be conveniently placed in an office or lab area, and it can also be either
shelf of wall-mounted (see instructions in 3.1.2 below). Wall-mounting brackets are included,
usable for single units (but not for stacks). The width of two LH8000A units will fit in a 19”
rack when they are side-by-side.

Locate an AC receptacle that is within six feet (2 meters) of the intended LH8000A
site. The rugged metal case of the LH8000A will normally protect it from accidental damage in
a lab or workplace setting. Maintain an open view of the front to visually monitor the status
LEDs. Keep an open area around the unit so that cooling can occur from the small fan in the
bottom-rear while the unit is in operation.

3.1.1 Table-Top or Shelf Mounting

The LH8000A Dual-Speed Hub can be easily mounted on a table-top or any suitable
horizontal surface, and has four rubber feet to provide stability without scratching finished
surfaces. When stacked, the rubber feet also provide separation between units for the exhaust
of the rear cooling fan.

3.1.2 Wall (or Vertical Surface) Mounting

Each LH8000A Dual-Speed Hub is shipped with two metal mounting brackets (and
screws) to allow the unit to be mounted in nearly any desired orientation or position. The
brackets are attached to the metal hub case using one of the metal screws for each bracket and
attaching to the LH8000A through the round hole of the bracket. A user-supplied screw
attaches the bracket to the mounting surface. It is recommended that the brackets be attached to
two opposite corners of the unit. When properly attached, the brackets will extend slightly
below the base of the unit to allow clearance for the rubber feet and the cooling fan exhaust.

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3.2 Connecting Ethernet Media

The LH8000A Dual-Speed Stackable Hubs can be connected to the following two
media types: 100BASE-TX and 10BASE-T. CAT 5 cables should be used when making
100BASE-TX connections. When the ports are used as 10BASE-T ports, CAT 3 may be used.
In either case, the maximum distance for unshielded twisted pair cabling is 100 meters (328 ft).

Media

IEEE Standard Connector

Twisted Pair (CAT 3) 10BASE-T RJ-45
Twisted Pair (CAT 5) 100BASE-TX RJ-45

NOTE : It is recommended that high quality CAT. 5 cables (which work for both 10Mb and

100Mb) be used whenever possible in order to provide flexibility in a mixed-speed

network, since dual-speed ports are auto-sensing for either 10 and 100Mb/s.

3.2.1 Connecting Twisted Pair (RJ-45, CAT 3 or CAT 5,

Unshielded or Shielded)

The following procedure describes how to connect a 10BASE-T or 100BASE-TX
twisted pair segment to the RJ-45 port. The procedure is the same for both unshielded and
shielded twisted pair cables.

1. Using standard twisted pair media, insert either end of the cable with an RJ-45 plug into
the RJ-45 connector of the port. Note that, even though the connector is shielded, either
unshielded or shielded cables and wiring may be used.

2. Connect the other end of the cable to the corresponding device.

3. Use the LINK LED to ensure proper connectivity by noting that the LED will be
illuminated when the unit is powered and proper connection is established. For Port #
8, if the LINK LED is not illuminated, change the setting of the up-link switch. If this
does not help, ensure that the cable is connected properly and that the device on the
other end is powered and is not defective.

3.2.2 100Mbps Collision Domain Diameter, Cable Distances

and PDV Calculations

The 100Mbps Collision Domain Diameter is the length of the longest path between
any two devices in a single collision domain. A collision domain is defined as a cluster of
network devices which are connected by means of a repeater or repeaters such that no bridging
devices are present between any two devices in the cluster. In order to install an IEEE 802.3u
compliant Fast Ethernet network, the collision domain . . regardless of the actual network

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topology . . must be less than 512 BT (Bit Times). Bit Times are related to media type as
shown in Table 3.2.2a.

Table 3.2.2a: Worst case round-trip delay for Fast Ethernet media*

Media Type Round-trip delay in

Bit Time per Meter (BT/m)
Fiber Optic 1.000
Shielded TP cable 1.112
Category 5 Cable 1.112
Category 3, 4 Cable 1.140

*Worst case delays taken from IEEE Std 802.3u-1995, actual delays may be less for a particular cable.
Contact your cable supplier for exact cable specifications.

Each Fast Ethernet device component also has an associated BT delay which depends
on the physical signaling system employed. Table 3.2.2b shows each Fast Ethernet device
component and the associated BT delay. A “DTE” is an end node, such as a user station. Note
that there is only one DTE pair associated with any device-to-device path.

Table 3.2.2b: Worst case round-trip delay for Fast Ethernet device components*

Component Round-trip delay in Bit Times (BT)
2 TX DTEs 100
2 FX DTEs 100
1 FX and 1 TX DTE 100
1 T4 and 1 TX or FX DTE 127
Class I Repeater 140
Class II Repeater with any

combination of TX and FX ports

92 **

**Note, the delay is only 80 Bit Times for

the LH8000A, front-port-to-front-port.

*Worst case delays taken from IEEE Std 802.3u -1995.

To determine whether a prospective network topology adheres to the collision
domain diameter specification, the following formula should be applied to the worst case path
through the network. The worst case path is the path between the two Fast Ethernet devices
(DTEs) which have the longest round-trip time.

PDV = (sum of cabling delays) + (sum of repeater delays) +

(DTE pair delay) + (safety margin)

PDV is the Path Delay Value of the worst case path. For the network to adhere to
IEEE standard, this value must be less than 512 BT. The safety margin is specified in BT and
may be a value between 0 and 5. This margin can be used to accommodate unexpected delays
such as extra long patch cable. A safety margin of about 2 to 4 BT is recommended.

A typical example of a PDV calculation is shown below, and is illustrated in Figure

3.2.2a. Here, an integrator wishes to cascade the 100Mbps collision domains of two Dual

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Speed LH8000A Hubs(each having a PDV of 80BT) for use with standard 100m Category 5
user cable segments (i.e. from computer to hub) and needs to know how long the inter-repeater
Category 5 cable segment, used to cascade the hubs, can be. The variable “X” represents the
unknown maximum cascade cable delay.

PDV = X + ((111 + 111) + (80 + 80) + (100) + 2 ) BT < 512 BT
512 > (X + 486) BT
X < (512 - 486 ) BT, X < 28 BT
Twisted Pair cable length, TL < (28 BT) / (1.112 m/BT)
TL < 25 meters

⇒ 25 m maximum total length for Category 5 inter-repeater segment,

where 111 is the BT delay for
100m of Category 5 cable (1.112
BT/m* 100m), 80 is the BT
delay for each LH8000A’s, 100
is the BT delay for the TX DTE
pair, and a safety margin of 2
was used.

Figure 3.2.2a: Two cascaded LH8000A hubs

The resulting value tells us that a Category 5 cable with a length of up to 30 meters
may be used to cascade the LH8000As. Note that this inter-repeater cable length may be
increased by shortening the lengths of the 100m hub-to-user cable segments.

It is also possible to cascade a group of up to nine LH8000As (serving up to 56 users
with full-length 75m cables to each) by using short inter-repeater cable segments. The
following is an example of how to calculate the maximum allowable cascade cable segment
length. An illustration of this example is shown in Figure 3.2.2b, where the hub-to-user cable
lengths are up to 100 meters for Cat 5 twisted pair. The variable “X”, the maximum hub-to-hub
cable delay, is calculated as follows:

PDV = X + ((100) + (80 + 80 + 80 )+ (83 + 83) + 2 ) BT < 512 BT

512 > (X + 508) BT, X < 4 BT

Twisted pair user cable length, TL < (4 BT) / (1.112 m/BT)

TL < 3.6 meters for two

hub-to-hub cascading cables

⇒ 2 meters (6 ft.) length max. for each of the cascade segments,

1 2 3 4 5 6 7 8

COL

ACT

PWR

LK
RX

BR UPLINK

1 2 3 4 5 6
7 8

100 m Cat. 5 cables

to user devices

100 m Cat. 5 cables

to user devices

Cat. 5 cable for

cascading

1 2 3 4 5 6 7 8

COL

ACT

PWR

LK
RX

BR UPLINK

1 2 3 4 5 6
7 8

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In the above example, 80 is the BT delay for 75m of Category 5 cable (1.112 BT/m), 80 is the
bit time delay for each LH8000A front-to-front ports, 100 is the BT delay for the TX DTE pair
in the user stations, and 2 BT is the safety margin applied.

Figure 3.2.2b: Multiple cascaded
Magnum LH8000A hubs

Note that the cascading of
multiple LH8000A hubs is a
capability beyond what industry
standards normally permit, and is
different from what competitive
Class II hub products normally
allow. This additional cascading
level and cable length is due to the
relatively shorter bit time (80 BT actually measured, for front-port-to-port) delay of the
100Mbps domain of the LH8000A vs. the industry standard delay of 92 BT for Class II
repeaters. The installation flexibility and network growth potential is accordingly better with
LH8000As than with hubs that merely meet the standard.

Table 3.2.2c shows maximum cable lengths for common network configurations
using industry standard repeater PDV numbers. Calculations such as above should be
performed using measured PDV data supplied by the equipment manufacturer in important
installations.

Table 3.2.2c: Maximum segment lengths for common network configurations

Number

of Hubs

Repeater

Hop Count

Max. User

Segment

Lengths (m)

Max. Inter-

Repeater (Cascade)

Length (m)

Notes

1 1 100.0 n.a. All ports TX
2 2 100.0 5.0 All ports TX
2 2 92.0 20.0 All ports TX

3+ 3 60.0 1.0 All ports TX

Instructions for connecting the LH8000A Dual-Speed Hubs to the various Fast
Ethernet media are given in the following sections.

2 meter Cat. 5 cable

for cascading

All user devices connected
via Cat. 5 twisted pair cable

of up to 75m length.

1 2 3 4 5 6 7 8

COL

ACT

PWR

LK
RX

BR UPLINK

1 2 3 4 5 6
7 8

1 2 3 4 5 6 7 8

COL

ACT

PWR

LK
RX

BR UPLINK

1 2 3 4 5 6
7 8

1 2 3 4 5 6 7 8

COL

ACT

PWR

LK
RX

BR UPLINK

1 2 3 4 5 6
7 8

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3.2.3 Connections to NICs which support Auto-Negotiation

The LH8000A Dual-Speed Hub will function properly with NICs (Network Interface
Cards) which support Auto-Negotiation. The LH8000A will establish link with any NIC which
can send and receive the Fast Link Pulse (FLP) coding for the 100BASE-TX signaling system.
When connecting a NIC to the LH8000A, it may be necessary to reload the NIC drivers on the
user device if the NIC has been communicating with a protocol other than 100BASE-TX (such
as 10BASE-T). When 100Mbps operation is agreed and in use, the 100Mbps LINK/ACT
LED is illuminated, steady ON if no traffic or blinking when there is traffic.

3.3 Powering the Dual-Speed Hub

LH8000A Dual-Speed Hub incorporates an internal universal power supply, and has a
recessed male IEC connector for the AC power cord in the rear. A six-foot 115 VAC 60Hz
power cord is supplied with each unit shipped within the United States and Canada.

Each LH8000As auto-ranging power supply supports installation environments where
the AC voltage is from 90 to 260 volts with an input frequency between 47 and 63 Hz, and
consumes a maximum of 20 watts. In order to power down the unit, simply unplug either end of
the AC power cable.

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4.0 OPERATION

This chapter describes the function and operation of the LH8000A hubs.

4.1 Dual-Speed Functionality

The LH8000A-C handles the two different traffic domains separately (unless it is
stacked with an LH8000A-M). The LH8000A-M provides switched (bridged) connectivity
between the Ethernet (10Mb/s) and Fast Ethernet (100Mb/s) domains. It joins the two network
domains for unified operation, and filters/ forwards packets in both directions to maximize
bandwidth utilization and performance. LH8000As are hardware plug-and-play devices. There
is no software set-up to be done at installation or for maintenance. The functions of the
LH8000As are described in this manual.

Each time a packet is received on one domain of the bridge module, the decision is
taken to either to filter or forward the packet. Errored packets are always filtered. For good
packets, the filter and forward decisions are made based on the destination address contained in
each packet. If the destination address is on the same domain from which the packet originated,
then it is filtered and not forwarded to the other domain. If the destination address is not found
to be a match in the address table for the originating domain, then it is forwarded to the other
domain. If it is a new node address coming in which the switch did not previously know about,
it “learns” the new address and puts it in the correct port address table. See “Address Learning”
for more details.

This diagram below shows the filter / forward logic for both domains.

LH8000A-M

Figure 4.1 : Filtering vs. Forwarding in Dual-Speed LH8000A-M unit

10 Mb Domain

100 Mb Traffic

100 Mb Domain

10Mb Domain : 10Mb packets are
forwarded when the destination addresse is
NOT

in the 10Mb domain address table.

100Mb Domain : 100Mb packets are
forwarded when the destination address is
NOT

in the 100Mb domain ad dress table.

10Mb Domain : 10Mb packets are
filtered when the destination address is

in the 10Mb domain address table.

100Mb Domain : 100Mb packets are
filtered when the destination address is

in the 100Mb domain address table.

Bridge Module

10 Mb Traffic

10 BUS 100

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Packet Source Destination Address Table Filter/Forward
Source

Address Address Maintenance Action

10 Mb Not in table Not in table Add source to table Forward
10 Mb Not in table In table Add source to table Filter
10 Mb In table Not in table None Forward
10 Mb In table In table None Filter
100 Mb Not in table Not in table Add source to table Forward
100 Mb Not in table In table Add source to table Filter
100 Mb In table Not in table None Forward
100 Mb In table In table None Filter

Table 4.1: LH8000A-M Dual-Speed Hub Functionality

2. Address Learning (Address Table Maintenance)

The LH8000A-M bridge module is a state machine design which has a total address
table capacity of 8K addresses. With a large address table, LH8000As can serve the needs of a
medium-sized to large network. Table 4.1 shows what filter / forward action the LH8000A-M
will take in each packet-processing situation, and when a new node address will be added to
the internal Address Table. When a new node-address packet comes into a port for the first
time, then the new source address is “learned” at the same time that the packet is forwarded.
After learning, subsequent packets from the same node address are routinely processed. The
address tables are flushed periodically to update the network status and to purge any inactive
stations from the tables of both domains.

3. Throughput Increase
By selectively forwarding packets from each domain to the other domain based on

its switching (bridging) logic, the LH8000A-M increases the available bandwidth for the users
on both sides of the network. As shown in Figure 4.1, it keeps the local traffic on each side
contained, preventing unnecessary packets and bad packets from traveling to the other domain
and using up bandwidth needlessly over there. This results in more available network
bandwidth on both sides and a throughput increase on for all users on both domains.

4. Software Transparency

The LH8000A-C and -M Dual-Speed Hubs need no software set-up and are
transparent to system and application software, including network management software.

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4.2 Auto-negotiation and speed-sensing

All eight RJ-45 ports independently support auto-negotiation for shared
10BASE-T and 100BASE-TX modes. When the ‘100’ LED is flashing, it means that the
corresponding port is sending out auto-negotiation pluses out that port. When a connection is
made, the other device should respond and both sides should agree to the speed being
advertised. Depending upon the device connected, it will either advertise at 10Mb or 100Mb
speeds. Silence means the port defaults to 10Mbps .
When the ‘100’ LED is steady ON, the port has auto-negotiated for 100Mbps
operation and is processing packets at 100Mbps , When it is OFF, it is at 10Mbps, 100 If an
LH8000A port is connected to a non-negotiating device, it will default to 10Mbps speed.
Since LH8000As are hubs, they always operate in the shared or half-duplex mode on all ports.

4.3 LEDs

PWR : Illuminates GREEN to indicate AC power is applied to the unit.

BR : Bridge Module LED-

ON when a bridge module is present in the unit (model LH8000A-M)

OFF when no

bridge module is present ( model LH8000A-C)

COL : Two collision LED’s, one for each traffic domain, 10 and 100Mbps

Blinks intermittently when a collision occurs.

ACT : Activity (Send or Receive) for each traffic domain, 10 and 100Mbps

100 : Speed LED, per port. Flashing when auto-negotiating (No LINK)

Steady ON when the port speed is 100Mbp/s, OFF for 10Mbp/s

LK : LINK LED, per port. Illuminates GREEN when a working

connection is established between the port and the attached device.

RX : Activity LED, per port. Flashes GREEN to indicate that the port is

receiving data from the attached device, i.e., there is activity on
the port.

4.4 Up-link Switch

The LH8000As have one up-link slide switch, used
with port 8. This allows repeater-to-repeater connections without
a special cross-over cable. It works the same for 10Mbps or
100Mbps connections.

Set the slide switch to the “=” position for twisted pair cabling from the
LH8000A port to a user device, or to the “X” position for cross-over or up-link segment
connections from the LH8000A port to a repeater or hub. Verify proper switch position by
noting the port’s LINK LED status, which is illuminated when a proper link is made.

UP-LIN

K

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5.0 TROUBLESHOOTING

If problems should develop during installation or operation, follow the
suggestions below prior to calling Technical Support for help. If you are unsure of any
procedure described in this chapter, or if the Dual-Speed Hub is not operating as
expected, do not attempt to repair or alter the unit. Contact Black Box for assistance.

5.1 Before Calling for Assistance

1. If you have difficulty installing or operating the Dual-Speed Hub, refer to Chapters 3

and 4. Make sure that the various other components of the network are working.

2. Check the cables and connectors to make sure that they have been properly connected

and the cables/wires have not been crimped or in some way impaired during
installation.

3. Check that the AC power cord is plugged into a functioning electrical outlet. Make

sure that the AC power cord is properly plugged into the Dual-Speed Hub. Use the
PWR LED to verify that the unit is receiving proper power.

4. If the problem is isolated to a network device other than the Dual-Speed Hub, replace

the problem device with a known good device. Verify whether or not the problem is
corrected. If it is not, go to step 5. If the problem is corrected, the Dual-Speed Hub
and its associated cables will function properly.

5. If the problem still exists, contact Black Box.

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5.2 When Calling for Assistance

If you determine that your Dual-Speed Hub is malfunctioning, do not attempt to

alter or repair the unit. It contains no user-serviceable parts. Contact Black Box at
[phone].

Before you do, make a record of the history of the problem. Black Box will be

able to provide more efficient and accurate assistance if you have a complete description,
including:

• the nature and duration of the problem.

• when the problem occurs.

• the components involved in the problem.

• any particular application that, when used, appears to create the problem or

make it worse.

5.3 Shipping and Packaging Information

If you need to transport or ship your Dual-Speed Hub:

• Package it carefully. We recommend that you use the original container.

• If you are shipping the Dual-Speed Hub for repair, make sure you include

everything that was in the original package. Before you ship, contact Black Box
and/or to get a Return Materials Authorization (RMA) number.

Ship the package to:

Black Box Corporation
1000 Park Drive
Lawrence, PA 15055
Phone: [phone]
Fax: [phone]