D-Link xStack Manual

_____________________________________________
Information in this document is subject to change without notice.
© 2013 D-Link Corporation. All rights reserved.
Reproduction in any manner whatsoever without the written permission of D-Link Corporation is strictly forbidden.
Trademarks used in this text: D-Link and the D-LINK logo are trademarks of D-Link Corporation; Microsoft and Windows are registered trademarks
of Microsoft Corporation.
Other trademarks and trade names may be used in this document to refer to either the entities claiming the marks and names or their products. D-
Link Corporation disclaims any proprietary interest in trademarks and trade names other than its own.
January, 2013 P/N 651G312XX065G
This equipment has been tested and found to comply with the limits for a Class A digital device, pursuant to Part 15 of
the FCC Rules. These limits are designed to provide reasonable protection against harmful interference when the
equipment is operated in a commercial environment. This equipment generates, uses, and can radiate radio
frequency energy and, if not installed and used in accordance with this manual, may cause harmful interference to
radio communications. Operation of this equipment in a residential area is likely to cause harmful interference in
which case the user will be required to correct the interference at his own expense.
FCC Warning
This is a Class A product. In a domestic environment, this product may cause radio interference in which case the
user may be required to take adequate measures.
CE Mark Warning
Dies ist ein Produkt der Klasse A. Im Wohnbereich kann dieses Produkt Funkstoerungen verursachen. In diesem Fall
kann vom Benutzer verlangt werden, angemessene Massnahmen zu ergreifen.
Warnung!
Este es un producto de Clase A. En un entorno doméstico, puede causar interferencias de radio, en cuyo case, puede
requerirse al usuario para que adopte las medidas adecuadas.
Precaución!
Ceci est un produit de classe A. Dans un environnement domestique, ce produit pourrait causer des interférences
radio, auquel cas l`utilisateur devrait prendre les mesures adéquates.
Attention!
Il presente prodotto appartiene alla classe A. Se utilizzato in ambiente domestico il prodotto può causare interferenze
radio, nel cui caso è possibile che l`utente debba assumere provvedimenti adeguati.
Attenzione!
この装置は、クラス A情報技術装置です。この装置を家庭環境で使用すると電波妨害を引き起こすことがあります。
この場合には使用者が適切な対策を講ずるよう要求されることがあります。 VCCI-A
VCCI Warning
此為甲類的資訊技術設備, 在居住環境中使用時, 可能會造成射頻擾動, 在這種情況下, 使用者會被要求採取某些適當的對
策
BSMI Notice

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Table of Contents
Intended Readers .........................................................................................................................................................v
Typographical Conventions..........................................................................................................................................v
Notes, Notices, and Cautions.......................................................................................................................................v
Safety Instructions ....................................................................................................................................................... vi
Safety Cautions....................................................................................................................................................... vi
General Precautions for Rack-Mountable Products....................................................................................................vii
Protecting Against Electrostatic Discharge.................................................................................................................viii
Chapter 1 Introduction................................................................................................................................................1
Switch Description ........................................................................................................................................................1
Features........................................................................................................................................................................2
Ports..............................................................................................................................................................................3
Front Panel Components..............................................................................................................................................5
LED Indicators..........................................................................................................................................................6
Rear Panel Description.................................................................................................................................................9
Side Panel Description ...............................................................................................................................................10
Chapter 2 Installation................................................................................................................................................11
Package Contents.......................................................................................................................................................11
Installation Guidelines.................................................................................................................................................11
Installing the Switch without a Rack.......................................................................................................................12
Attaching Brackets to a Switch for Rack Mounting.................................................................................................12
Mounting the Switch in a Standard 19" Rack.........................................................................................................13
Power On (AC Power)................................................................................................................................................13
Power Failure (AC Power)......................................................................................................................................13
Connecting DC Power to the DGS-3120-24SC-DC ...................................................................................................14
Installing SFP Ports ....................................................................................................................................................15
Connecting to a Redundant Power Supply.................................................................................................................16
Installing the RPS into a Rack-mount Chassis...........................................................................................................17
DPS-700.................................................................................................................................................................17
DPS-800.................................................................................................................................................................18
DPS-900.................................................................................................................................................................19
Chapter 3 Connecting the Switch............................................................................................................................21
Switch to End Node....................................................................................................................................................21
Switch to Switch..........................................................................................................................................................22
Connecting to Network Backbone or Server ..............................................................................................................23
Chapter 4 Introduction to Switch Management .....................................................................................................24
Management Options .................................................................................................................................................24
Connecting the Console Port......................................................................................................................................24
First Time Connecting to the Switch...........................................................................................................................26
Password Protection...................................................................................................................................................26
IP Address Assignment ..............................................................................................................................................27
SNMP Settings............................................................................................................................................................27
Traps.......................................................................................................................................................................28
MIBs........................................................................................................................................................................28
Chapter 5 Web-based Switch Configuration..........................................................................................................29
Introduction.................................................................................................................................................................29
Logging onto the Web Manager .................................................................................................................................29
Web-based User Interface..........................................................................................................................................30
Areas of the User Interface.....................................................................................................................................30
Web Pages .................................................................................................................................................................31

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Appendix A –Technical Specifications......................................................................................................................32
General.......................................................................................................................................................................32
Physical and Environmental .......................................................................................................................................33
Performance ...............................................................................................................................................................33
LED Indicators ............................................................................................................................................................34
Port Functions.............................................................................................................................................................36
Appendix B –Cables and Connectors........................................................................................................................38
Ethernet Cable............................................................................................................................................................38
Console Cable ............................................................................................................................................................39
Redundant Power Supply (RPS) Cable......................................................................................................................40
Appendix C –Module Specs and Cable Lengths.......................................................................................................43

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Intended Readers
Typographical Conventions
Notes, Notices, and Cautions
Safety Instructions
General Precautions for Rack-Mountable Products
Protecting Against Electrostatic Discharge
The DGS-3120 Series Hardware Installation Guide contains information for set up and management of the Switch.
This manual is intended for network managers familiar with network management concepts and terminology. For all
practical reasons the DGS-3120-24TC, DGS-3120-24SC, DGS-3120-24SC-DC,DGS-3120-24PC, DGS-3120-48TC,
and DGS-3120-48PC will be simply refered to as the Switch throughout this manual. All example screenshots are
taken from the DGS-3120-24TC Switch. In some examples, where we refer to the Power over Ethernet examples,
we’ll use the DGS-3120-24PC Switch.
Typographical Conventions
Convention Description
[ ]
In a command line, square brackets indicate an optional entry. For example: [copy
filename] means that optionally you can type copy followed by the name of the file. Do
not type the brackets.
Bold font
Indicates a button, a toolbar icon, menu, or menu item. For example: Open the File
menu and choose Cancel. Used for emphasis. May also indicate system messages or
prompts appearing on screen. For example: You have mail. Bold font is also used to
represent filenames, program names and commands. For example: use the copy
command.
Boldface Typewriter
Font
Indicates commands and responses to prompts that must be typed exactly as printed
in the manual.
Initial capital letter
Indicates a window name. Names of keys on the keyboard have initial capitals. For
example: Click Enter.
Menu Name > Menu
Option
Menu Name > Menu Option Indicates the menu structure. Device > Port > Port
Properties means the Port Properties menu option under the Port menu option that is
located under the Device menu.
Notes, Notices, and Cautions
A NOTE indicates important information that helps make better use of the device.
A NOTICE indicates either potential damage to hardware or loss of data and tells how to avoid the
problem.
A CAUTION indicates a potential for property damage, personal injury, or death.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Safety Instructions
Use the following safety guidelines to ensure your own personal safety and to help protect your system from potential
damage. Throughout this safety section, the caution icon ( ) is used to indicate cautions and precautions that need
to be reviewed and followed.
Safety Cautions
To reduce the risk of bodily injury, electrical shock, fire, and damage to the equipment, observe the following
precautions.
•Observe and follow service markings.
oDo not service any product except as explained in the system documentation.
oOpening or removing covers that are marked with the triangular symbol with a lightning bolt may
expose the user to electrical shock.
oOnly a trained service technician should service components inside these compartments.
•If any of the following conditions occur, unplug the product from the electrical outlet and replace the part or
contact your trained service provider:
oDamage to the power cable, extension cable, or plug.
oAn object has fallen into the product.
oThe product has been exposed to water.
oThe product has been dropped or damaged.
oThe product does not operate correctly when the operating instructions are correctly followed.
•Keep your system away from radiators and heat sources. Also, do not block cooling vents.
•Do not spill food or liquids on system components, and never operate the product in a wet environment. If the
system gets wet, see the appropriate section in the troubleshooting guide or contact your trained service
provider.
•Do not push any objects into the openings of the system. Doing so can cause fire or electric shock by shorting
out interior components.
•Use the product only with approved equipment.
•Allow the product to cool before removing covers or touching internal components.
•Operate the product only from the type of external power source indicated on the electrical ratings label. If
unsure of the type of power source required, consult your service provider or local power company.
•To help avoid damaging the system, be sure the voltage selection switch (if provided) on the power supply is
set to match the power available at the Switch’s location:
o115 volts (V)/60 hertz (Hz) in most of North and South America and some Far Eastern countries such
as South Korea and Taiwan
o100 V/50 Hz in eastern Japan and 100 V/60 Hz in western Japan
o230 V/50 Hz in most of Europe, the Middle East, and the Far East
•Also, be sure that attached devices are electrically rated to operate with the power available in your location.
•Use only approved power cable(s). If you have not been provided with a power cable for your system or for
any AC-powered option intended for your system, purchase a power cable that is approved for use in your
country. The power cable must be rated for the product and for the voltage and current marked on the
product's electrical ratings label. The voltage and current rating of the cable should be greater than the ratings
marked on the product.
•To help prevent electric shock, plug the system and peripheral power cables into properly grounded electrical
outlets. These cables are equipped with three-prong plugs to help ensure proper grounding. Do not use
adapter plugs or remove the grounding prong from a cable. If using an extension cable is necessary, use a 3-
wire cable with properly grounded plugs.
•Observe extension cable and power strip ratings. Make sure that the total ampere rating of all products
plugged into the extension cable or power strip does not exceed 80 percent of the ampere ratings limit for the
extension cable or power strip.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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•To help protect the system from sudden, transient increases and decreases in electrical power, use a surge
suppressor, line conditioner, or uninterruptible power supply (UPS).
•Position system cables and power cables carefully; route cables so that they cannot be stepped on or tripped
over. Be sure that nothing rests on any cables.
•Do not modify power cables or plugs. Consult a licensed electrician or your power company for site
modifications. Always follow your local/national wiring rules.
•When connecting or disconnecting power to hot-pluggable power supplies, if offered with your system,
observe the following guidelines:
oInstall the power supply before connecting the power cable to the power supply.
oUnplug the power cable before removing the power supply.
oIf the system has multiple sources of power, disconnect power from the system by unplugging all
power cables from the power supplies.
oMove products with care; ensure that all casters and/or stabilizers are firmly connected to the system.
Avoid sudden stops and uneven surfaces.
•The -48VDC input connector of the DGS-3120-24SC-DC has no protective cage on it. To avoid injury, don’t
touch the connector when powered.
General Precautions for Rack-Mountable Products
Observe the following precautions for rack stability and safety. Also, refer to the rack installation documentation
accompanying the system and the rack for specific caution statements and procedures.
Systems are considered to be components in a rack. Thus, "component" refers to any system as well as to various
peripherals or supporting hardware.
CAUTION: Installing systems in a rack without the front and side stabilizers installed could cause the
rack to tip over, potentially resulting in bodily injury under certain circumstances. Therefore, always
install the stabilizers before installing components in the rack. After installing system/components in a
rack, never pull more than one component out of the rack on its slide assemblies at one time. The
weight of more than one extended component could cause the rack to tip over and may result in
serious injury.
•Before working on the rack, make sure that the stabilizers are secured to the rack, extended to the floor, and
that the full weight of the rack rests on the floor. Install front and side stabilizers on a single rack or front
stabilizers for joined multiple racks before working on the rack.
•Always load the rack from the bottom up, and load the heaviest item in the rack first.
•Make sure that the rack is level and stable before extending a component from the rack.
•Use caution when pressing the component rail release latches and sliding a component into or out of a rack;
the slide rails can pinch your fingers.
•After a component is inserted into the rack, carefully extend the rail into a locking position, and then slide the
component into the rack.
•Do not overload the AC supply branch circuit that provides power to the rack. The total rack load should not
exceed 80 percent of the branch circuit rating.
•Ensure that proper airflow is provided to components in the rack.
•Do not step on or stand on any component when servicing other components in a rack.
NOTE: A qualified electrician must perform all connections to DC power and to safety grounds. All
electrical wiring must comply with applicable local, regional or national codes and practices.
CAUTION: Never defeat the ground conductor or operate the equipment in the absence of a suitably
installed ground conductor. Contact the appropriate electrical inspection authority or an electrician if
uncertain that suitable grounding is available.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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CAUTION: The system chassis must be positively grounded to the rack cabinet frame. Do not
attempt to connect power to the system until grounding cables are connected. Completed power and
safety ground wiring must be inspected by a qualified electrical inspector. An energy hazard will exist
if the safety ground cable is omitted or disconnected.
Protecting Against Electrostatic Discharge
Static electricity can harm delicate components inside the system. To prevent static damage, discharge static
electricity from your body before touching any of the electronic components, such as the microprocessor. This can be
done by periodically touching an unpainted metal surface on the chassis.
The following steps can also be taken prevent damage from electrostatic discharge (ESD):
1. When unpacking a static-sensitive component from its shipping carton, do not remove the component from
the antistatic packing material until ready to install the component in the system. Just before unwrapping the
antistatic packaging, be sure to discharge static electricity from your body.
2. When transporting a sensitive component, first place it in an antistatic container or packaging.
3. Handle all sensitive components in a static-safe area. If possible, use antistatic floor pads, workbench pads
and an antistatic grounding strap.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Chapter 1 Introduction
Switch Description
Features
Ports
Front Panel Components
Rear Panel Description
Side Panel Description
Switch Description
D-Link's DGS-3120 Series is a high performance member of the D-Link xStack®family. Ranging from 10/100Mbps
edge switches to core gigabit switches, the xStack®switch family has been future-proof designed to provide fault
tolerance, flexibility, port density, robust security, and maximum throughput, with a user-friendly management interface
for the networking professional.
The Switch is the latest member of D-Link’s entry level Layer 2 managed switch product line.
The Series features the following list of switches:
•DGS-3120-24TC: 20 Ethernet 10/100/1000 Ports + 4 combo 10/100/1000BASE-T/SFP ports L2 Stackable
Management Switch
•DGS-3120-48TC: 44 Ethernet 10/100/1000 Ports + 4 combo 10/100/1000BASE-T/SFP ports L2 Stackable
Management Switch
•DGS-3120-24PC: 20 Ethernet 10/100/1000 Ports + 4 combo 10/100/1000BASE-T/SFP ports PoE L2
Stackable Management Switch
•DGS-3120-48PC: 44 Ethernet 10/100/1000 Ports + 4 combo 10/100/1000BASE-T/SFP ports PoE L2
Stackable Management Switch
•DGS-3120-24SC: 16 SFP ports + 8 combo 10/100/1000BASE-T/SFP ports L2 Stackable Management Switch
•DGS-3120-24SC-DC: 16 SFP ports + 8 combo 10/100/1000BASE-T/SFP ports L2 Stackable Management
Switch with DC power
This cost effective Gigabit Switch provides an affordable solution for administrators to upgrade their networks to high
speed Gigabit connections. The dedicated stacking ports offer up to 40G bi-directional bandwidth, which makes the
DGS-3120 Series also suitable as a backbone solution for SMBs. The advanced ACL and user authentication
functions on the Switch extend the network security coverage from core to the edge. A unique D-Link Safeguard
Engine protects the DGS-3120 Series from the threat of worms and viruses, thereby increasing overall reliability,
serviceability, and availability.
The Switch has a combination of 1000BASE-T ports and SFP ports that may be used in uplinking various network
devices to the Switch, including PCs, hubs and other switches to provide a gigabit Ethernet uplink in full-duplex mode.
The SFP (Small Form Factor Portable) combo ports are used with fiber-optical transceiver cabling in order to uplink
various other networking devices for a gigabit link that may span great distances.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Features
The list below highlights the significant protocols and features supported by the Switch.
•IEEE 802.3 Ethernet compliant
•IEEE 802.3z 1000Base-X compliant
•IEEE 802.3x Flow Control in full-duplex compliant
•IEEE 802.3u 100Base-TX compliant
•IEEE 802.3ab 1000Base-T compliant
•IEEE 802.1p Priority Queues
•IEEE 802.3ad Link Aggregation Control Protocol
•IEEE 802.1X Port-based and Host-based Access Control
•IEEE 802.1Q VLAN
•IEEE 802.1D Spanning Tree
•IEEE 802.1w Rapid Spanning Tree
•IEEE 802.1s Multiple Spanning Tree
•Support Jumbo frame to 13K Bytes
•Access Control List (ACL)
•ISM VLAN
•DHCP local relay
•Single IP Management
•Access Authentication Control utilizing TACACS, XTACACS, TACACS+, and RADIUS protocols
•Compound Authentication
•Power saving mode
•Simple Network Time Protocol (SNTP)
•System Log
•Maximum packet forwarding rate 65.48 Mpps
•High performance switching engine performs forwarding and filtering at full wire speed up to 136Gps
•Full- and half-duplex for all ports.
•Unicast, broadcast, and multicast storm control
•Loopback Detection (LBD)
•Efficient self-learning and address recognition mechanism enables forwarding rate at wire speed
•MAC Address table: up to 16 K
•Packet buffer memory of up to 2 MByte
•Two stacking ports in the rear of the switch
•VLAN Trunking
•Private VLAN
•802.1Q (2005 edition) VLAN
•GVRP
•Voice VLAN
•VLAN tagging based on PVID
•IGMP Snooping v1/v2/v3
•MLD Snooping v1 and v2
•SNMP v1/v2/v3
•SNMP over IPv6
•Secure Sockets Layer (SSL) v1/v2/v3
•Secure Shell (SSH) v2
•Port Mirroring

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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•LLDP
•NLB
•Traffic segmentation
•D-Link Safeguard Engine
•Web-based Access Control (WAC)
•MAC-based Access Control (MAC)
•Guest VLAN
•Microsoft® NAP--IPv4 and IPv6, 802.1X NAP, and DHCP NAP
•Database Failover
•RADIUS accounting
•RADIUS authentication for management access
•TACACS+ authentication for management access
•User account privilege for management access—four levels of user accounts
•DHCP server screening
•ARP spoofing prevention
•MIB support for:
oRFC 1213 MIB II
oRFC 4188 Bridge MIB
oRFC 1907 SNMPv2 MIB
oRFC 2819 RMON MIB
oRFC 2021 RMONv2 MIB
oRFC 2571 SNMP MIB, RFC 2572 SNMP MIB, RFC 2573 SNMP MIB
oRFC 2574 SNMPv3 MIB
oRFC 2575 VACM for SNMP MIB
oRFC 2576 SNMPv1, v2 & v3 MIB
oRFC 2665 Ether-like MIB
oRFC 4363 P-Bridge MIB and Q-Bridge MIB
oRFC 2863 IF MIB
oRFC 2618 RADIUS Authentication Client MIB
oRFC 2620 RADIUS Accounting Client MIB
oRFC 2925 Ping and Traceroute MIB
oPrivate MIB
oRFC 4293 IPv6 MIB
oRFC 4022 TCP MIB
oLLDP MIB
oLLDP-DOT1-MIB, LLDP-DOT3-MIB
•Provides parallel LED display for port status such as link/act, speed, etc.
•Web-based GUI compatible with most major browsers, including Internet Explorer (version 5.5 and later), Mozilla
Firefox (version 2.0 and later), Safari (version 4.0 and later), and Google Chrome (version 6.0 and later).
Ports
DGS-3120-24TC
Twenty-four Copper ports (10/100/1000Mbps).
Four Combo Copper/SFP ports (10/100/1000Mbps and 100/1000Mbps).
Two dedicated, high speed stacking ports.
DGS-3120-24SC
Sixteen SFP ports (100/1000Mbps).
Eight Combo Copper/SFP ports (10/100/1000Mbps and 100/1000Mbps).
Two dedicated, high speed stacking ports.
DGS-3120-24SC-DC
Sixteen SFP ports (100/1000Mbps).

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Eight Combo Copper/SFP ports (10/100/1000Mbps and 100/1000Mbps).
Two dedicated, high speed stacking ports.
DGS-3120-24PC
Twenty-four Copper PoE ports (10/100/1000Mbps).
Four Combo Copper/SFP ports (10/100/1000Mbps and 100/1000Mbps).
Two dedicated, high speed stacking ports.
DGS-3120-48TC
Fourty-four Copper ports (10/100/1000Mbps).
Four Combo Copper/SFP ports (10/100/1000Mbps and 100/1000Mbps).
Two dedicated, high speed stacking ports.
DGS-3120-48PC
Fourty-eight Copper PoE ports (10/100/1000Mbps).
Four Combo Copper/SFP ports (10/100/1000Mbps and 100/1000Mbps).
Two dedicated, high speed stacking ports.
•All the switches are equipt with one RJ-45 Console port (a special console cable with a DB9 interface is provided
to connect the Switch to a PC)
•All the switches, except for the DGS-3120-24SC-DC, are equipt with one Redundant Power Supply (RPS) outlet
for optional external RPS
NOTE: For customers interested in D-View, D-Link Corporation's proprietary SNMP management
software, go to http://dview.dlink.com.tw/ and download the software and manual.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Front Panel Components
The front panel of the Switch consists of LED indicators for Power, Console, RPS, Master, S1, S2, Fan, SD, Stack ID,
and for Link/Act for each port on the Switch including SFP port LEDs. A separate table below describes LED
indicators in more detail. The DGS-3120-24PC and DGS-3120-48PC switches are equipt with an additional PoE light,
to indication whether the ports are running in Power over Ethernet mode.
Figure 1-1 Front panel view of the DGS-3120-24TC
Figure 1-2 Front panel view of the DGS-3120-24SC
Figure 1-3 Front panel view of the DGS-3120-24SC-DC
Figure 1-4 Front panel view of the DGS-3120-24PC
Figure 1-5 Front panel view of the DGS-3120-48TC
Figure 1-6 Front panel view of the DGS-3120-48PC

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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LED Indicators
The Switch front panel presents LED indicators for Power, Console, RPS, Master (stack control), S1, S2, Fan, SD,
Stack ID and Link/Act indicators for all ports including the Gigabit Ethernet ports. The DGS-3120-24PC and DGS-
3120-48PC switches are equipt with an additional PoE light, to indication whether the ports are running in Power over
Ethernet mode.
Figure 1-7 LED indicators for the DGS-3120-24TC
Figure 1-8 LED indicators for the DGS-3120-24SC
Figure 1-9 LED indicators for the DGS-3120-24SC-DC

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Figure 1-10 LED indicators for the DGS-3120-24PC
Figure 1-11 LED indicators for the DGS-3120-48TC
Figure 1-12 LED indicators for the DGS-3120-48PC
LED Description
Power This LED will light green after powering the Switch on to indicate the ready state of the
device. The indicator is dark when the Switch is no longer receiving power (i.e. powered
off).
Console This LED will blink green during the Power-On Self Test (POST). When the POST is
finished, the LED goes dark. The indicator will light steady green when a user is logged
in through the console port.
RPS This LED will light green if the Redundant Powers Supply is in use. If the indicator is off,
the RPS is not in use. When the switch detects that the RPS is connected, the light will
be blinking. This LED in not available on the DGS-3120-24SC-DC switch.
Master For standalone Switches, this will light green. For stacked Switches, a solid Green light
indicates this unit is the Master of the stack.
S1 A solid green stacking port 1 LED indicates there is a secure connection (or link) to an
Ethernet device at any of the ports. The LED blinks green where there is reception or
transmission of data occurring at a port. A darkened LED indicates no link on this
stacking module.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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S2 A solid green stacking port 2 LED indicates there is a secure connection (or link) to an
Ethernet device at any of the ports. The LED blinks green where there is reception or
transmission of data occurring at a port. A darkened LED indicates no link on this
stacking module.
Fan This LED blinks red when a fan fails. No light indicates all fans are working normally.
SD This LED will light green if a Secure Digital (SD) card is plugged in. When the Switch is
reading or writing, the indicator will blink green. No light LED means there is no link. A
solid red LED indicates SD card failure.
Stack ID For standalone Switches, this will display number “1”. For stacked Switches, this
indicates the position in the stacking box ID. The box ID is assigned either by the user
(static mode) or by the system (automatic mode). When “1” to “6” is displayed, this
indicates the stacking position of the switch. An “H” indicates the device was assigned
as the stacking Master. “h“ means the device was selected to be the Backup Master. A
“G” is displayed when the Safeguard Engine feature enters the exhausted mode.
Link/Act LEDs The Switch has LED indicators for Link and Activity. The LED will light steady green
when there is a secure connection (or link) to a 1000Mbps Ethernet device at any of the
ports, or steady orange when there is a secure connection (or link) to a 10/100Mbps
Ethernet device at any of the ports. The LED will blink green when a 1000Mbps port is
active, or blink orange when a 10/100Mbps port is active. The LED remains dark when
there is no link or activity.
PoE Only the DGS-3120-24PC and the DGS-3120-48PC switches are equipt with a PoE
LED. When this light is on with a solid green light, it means that the corresponding ports
are feeding power to the PoE devices plugged in. When this light is on with a solid
orange light, it means that the port is in an error condition state. When this light is off, it
means that the ports are not supplying power to the devices plugged into the ports.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Rear Panel Description
The rear panel contains an AC power connector, an outlet for an external redundant power supply, and two stacking
ports.
Figure 1-13 Rear panel view of the DGS-3120-24TC
Figure 1-14 Rear panel view of the DGS-3120-24SC
Figure 1-15 Rear panel view of the DGS-3120-24SC-DC
Figure 1-16 Rear panel view of the DGS-3120-24PC
Figure 1-17 Rear panel view of the DGS-3120-48TC
Figure 1-18 Rear panel view of the DGS-3120-48PC
The AC power connector is a standard three-pronged connector that supports the power cord. Plug-in the female
connector of the provided power cord into this socket, and the male side of the cord into a power outlet. The Switch
automatically adjusts the power setting to any supply voltage in the range from 100 to 240 VAC at 50 to 60 Hz. An
optional external Redundant Power Supply (DPS-200 for DGS-3120-24TC/SC, DPS-500/DPS-500DC for DGS-3120-
48TC, and DPS-700 for DGS-3120-24PC/48PC) can be plugged into the RPS outlet displayed above. When the
internal power fails, this optional external RPS will take over all the power immediately and automatically. There are
also two stacking ports on the rear panel. These dedicated stacking ports are specially designed for high speed switch

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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stacking. The Switch supports a stacking cable length of up to 3 meters.
Side Panel Description
The system heat vents located on each side dissipate heat. Do not block these openings. Leave at least 6 inches of
space at the rear and sides of the Switch for proper ventilation. Be reminded that without proper heat dissipation and
air circulation, system components might overheat, which could lead to system failure or even severely damage
components.
Figure 1-19 Identical side panels of the DGS-3120-24TC, DGS-3120-24SC, and DGS-3120-24SC-DC
Figure 1-20 Identical side panels of the DGS-3120-24PC
Figure 1-21 Identical side panels of the DGS-3120-48TC
Figure 1-22 Identical side panels of the DGS-3120-48PC

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Chapter 2 Installation
Package Contents
Installation Guidelines
Power On (AC Power)
Connection DC Power to the DGS-3120-24SC-DC
Insatalling SFP Ports
Connecting to a Redundant Power Supply
External Redundant Power System
Package Contents
Open the shipping carton of the Switch and carefully unpack its contents. The carton should contain the following
items:
•One DGS-3120 Series Switch
•One Quick Installation Guide
•AC power cord(s)
•One RJ-45 to RS-232 console
•One mounting kit (two brackets and screws)
•Four rubber feet with adhesive backing
•One CD kit for Web UI Reference Guide, CLI Reference Guide, and D-View module
If any item is missing or damaged, please contact your local D-Link reseller for replacement.
Installation Guidelines
Please follow these guidelines for setting up the Switch:
•Install the Switch on a sturdy, level surface that can support at least 13.9 lb. (6.3 kg) of weight. Do not place
heavy objects on the Switch.
•The power outlet should be within 1.82 meters (6 feet) of the Switch.
•Visually inspect the power cord and see that it is fully secured to the AC power port.
•Make sure that there is proper heat dissipation from and adequate ventilation around the Switch. Leave at
least 10 cm (4 inches) of space at the front and rear of the Switch for ventilation.
•Install the Switch in a fairly cool and dry place for the acceptable temperature and humidity operating ranges.
•Install the Switch in a site free from strong electromagnetic field generators (such as motors), vibration, dust,
and direct exposure to sunlight.
•When installing the Switch on a level surface, attach the rubber feet to the bottom of the device. The rubber
feet cushion the Switch, protect the casing from scratches and prevent it from scratching other surfaces.

xStack® DGS-3120 Series Layer 2 Managed Stackable Gigabit Switch Hardware Installation Guide
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Installing the Switch without a Rack
First, attach the rubber feet included with the Switch if installing on a desktop or shelf. Attach these cushioning feet on
the bottom at each corner of the device. Allow enough ventilation space between the Switch and any other objects in
the vicinity.
Rubber Feet
Figure 2-1 Prepare the Switch for installation on a desktop or shelf
Attaching Brackets to a Switch for Rack Mounting
The Switch can be mounted in a standard 19" rack using the provided mounting brackets. Use the following diagrams
as a guide.
Figure 2-2 Fasten mounting brackets on the Switch
Fasten the mounting brackets to the Switch using the screws provided. With the brackets attached securely, the
Switch can be mounted in a standard rack, as shown below.
NOTE: Please review the Installation Guidelines above before installing the Switch in a rack. Make
sure there is adequate space around the Switch to allow for proper air flow, ventilation, and
cooling.