D-Link DGS-3224TGR User Guide
D-Link ™ DGS-3224TGR
Managed 24-Port Gigabit Ethernet Switch
User’s Guide
____________________
Information in this document is subject to change without notice.
© 2003 D-Link Computer Corporation. All rights reserved.
Reproduction in any manner whatsoever without the written permission of D-Link Computer Corporation is strictly forbidden.
Trademarks used in this text: D-Link and the D-Link logo are trademarks of D-Link Computer 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
Computer Corporation disclaims any proprietary interest in trademarks and trade names other than its own.
FCC Warning
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 user’s guide, 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.
CE Mark 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.
Warnung!
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.
Precaución!
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.
Attention!
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.
Attenzione!
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.
VCCI Warning
BSMI Warning
October 2003 P/N 6GS3224TGR01
Table of Contents
Features ............................................................................................................................................. 1
Ports ................................................................................................................................................ 1
Performance Features......................................................................................................................... 1
Management .................................................................................................................................... 2
Unpacking .......................................................................................................................................... 4
Installation ......................................................................................................................................... 4
Desktop or Shelf Installation ............................................................................................................ 4
Rack Installation.............................................................................................................................. 5
Power on............................................................................................................................................. 6
Power Failure ................................................................................................................................... 6
External Redundant Power System ..................................................................................................... 6
Front Panel......................................................................................................................................... 8
Rear Panel .......................................................................................................................................... 8
Side Panels ......................................................................................................................................... 9
LED Indicators ................................................................................................................................... 9
Switch to End Node .......................................................................................................................... 11
Switch to Hub or Switch ................................................................................................................... 11
Local Console Management .............................................................................................................. 13
Diagnostic (console) port (RS-232 DCE)..........................................................................................13
IP Addresses and SNMP Community Names ..................................................................................... 14
Setting an IP Address ....................................................................................................................... 14
Traps................................................................................................................................................ 14
MIBs................................................................................................................................................. 15
SNMP ............................................................................................................................................... 16
Authentication ............................................................................................................................... 16
Packet Forwarding ............................................................................................................................ 16
MAC Address Aging Time ............................................................................................................... 16
Filtering............................................................................................................................................ 17
Spanning Tree Protocol ..................................................................................................................... 17
STP Operation Levels ..................................................................................................................... 18
Bridge Protocol Data Units ............................................................................................................. 18
Creating a Stable STP Topology ...................................................................................................... 19
STP Port States .............................................................................................................................. 19
User-Changeable STP Parameters ..................................................................................................21
Illustration of STP .......................................................................................................................... 22
VLANs .............................................................................................................................................. 23
IEEE 802.1Q VLANs....................................................................................................................... 24
802.1Q VLAN Packet Forwarding ...................................................................................................24
802.1Q VLAN Tags ......................................................................................................................... 25
Port VLAN ID.................................................................................................................................. 26
Tagging and Untagging................................................................................................................... 27
Ingress Filtering ............................................................................................................................. 27
DHCP ............................................................................................................................................... 28
Introduction ..................................................................................................................................... 30
Getting Started ................................................................................................................................. 30
Basic Setup ...................................................................................................................................... 34
Switch Information......................................................................................................................... 34
Basic Switch Setup ........................................................................................................................ 38
Serial Port Settings ........................................................................................................................ 39
Port Configurations ........................................................................................................................ 41
User Accounts................................................................................................................................ 43
Network Management .................................................................................................................... 46
Switch Utilities............................................................................................................................... 55
Network Monitoring........................................................................................................................ 58
Factory Reset ................................................................................................................................. 68
Save Changes................................................................................................................................. 68
Restart System............................................................................................................................... 69
Logout............................................................................................................................................ 69
Advanced Setup................................................................................................................................ 69
Switch Advanced Settings .............................................................................................................. 70
Spanning Tree................................................................................................................................ 70
Forwarding..................................................................................................................................... 73
Configure QOS ............................................................................................................................... 79
Access Profile Mask Setting ............................................................................................................ 84
Port Security .................................................................................................................................. 90
Mirroring Configurations................................................................................................................ 93
VLAN Configurations...................................................................................................................... 93
Link Aggregation ............................................................................................................................ 98
802.1X ......................................................................................................................................... 100
System Log................................................................................................................................... 110
Multicast Configuration ............................................................................................................... 112
SSH Management......................................................................................................................... 114
Troubleshooting STP....................................................................................................................... 127
DGS-3224TGR Gigabit Ethernet Switch User’s Guide
Preface
The DGS-3224TGR User’s Guide is divided into chapters that describe the system installation and operating
instructions with examples.
Chapter 1, “Introduction” – Describes the Switch and its features.
Chapter 2, “Unpacking and Setup” – Helps you get started with the basic
installation of the Switch.
Chapter 3, “Identifying External Components” – Describes the front panel,
rear panel, and LED indicators of the Switch.
Chapter 4, “Connecting the Switch” – Tells how you can connect the
DGS-3224TGR to your Gigabit Ethernet network.
Chapter 5, “Switch Management and Operating Concepts” – Talks about
management via the RS-232 DCE console port and other aspects about how to
manage the Switch.
Chapter 6, “Web-Based Network Management” – Tells how to manage the
Switch through an Internet browser.
Appendix A, “Technical Specifications” – Lists the technical specifications of
the DGS-3224TGR.
Appendix B, “Cable Lengths” – Contains chart for fiber-optic and copper cable
maximum distances.
Appendix C, “Understanding and Troubleshooting the Spanning Tree
Protocol”
Glossary – Lists definitions for terms and acronyms used in this document.
Intended Readers
The DGS-3224TGR User’s Guide contains information for setup and management and of the DGS-3224TGR
switch. This guide is intended for network managers familiar with network management concepts and
terminology.
Notes, Notices, and Cautions
NOTE: A NOTE indicates important information that helps you make better use of your
device.
NOTICE: A NOTICE indicates either potential damage to hardware or loss of data and tells
you how to avoid the problem.
CAUTION: A CAUTION indicates a potential for property damage, personal injury, or death.
DGS-3224TGR Gigabit Ethernet Switch User’s Guide
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 you need to review and
follow.
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. Do not service any product except as explained in your system documentation. Opening
or removing covers that are marked with the triangular symbol with a lightning bolt may expose you to electrical shock. Only
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:
– The power cable, extension cable, or plug is damaged.
– An object has fallen into the product.
– The product has been exposed to water.
– The product has been dropped or damaged.
– The product does not operate correctly when you follow the operating instructions.
• Keep your system away from radiators and heat sources. Also, do not block cooling vents.
• Do not spill food or liquids on your system components, and never operate the product in a wet environment. If the
system gets wet, see the appropriate section in your troubleshooting guide or contact your trained service provider.
• Do not push any objects into the openings of your 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 you are
not sure of the type of power source required, consult your service provider or local power company.
• To help avoid damaging your system, be sure the voltage selection switch (if provided) on the power supply is set to
match the power available at your location:
– 115 volts (V)/60 hertz (Hz) in most of North and South America and some Far Eastern countries such as South
Korea and Taiwan
– 100 V/50 Hz in eastern Japan and 100 V/60 Hz in western Japan
– 230 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.
DGS-3224TGR Gigabit Ethernet Switch User’s Guide
Safety Instructions (continued)
• 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 you must use an extension cable, 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.
• To help protect your 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:
– Install the power supply before connecting the power cable to the power supply.
– Unplug the power cable before removing the power supply.
– If the system has multiple sources of power, disconnect power from the system by
unplugging all power cables from the power supplies.
• Move products with care; ensure that all casters and/or stabilizers are firmly connected to the system. Avoid sudden
stops and uneven surfaces.
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.
DGS-3224TGR Gigabit Ethernet Switch User’s Guide
Safety Instructions (continued)
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.
A qualified electrician must perform all connections to DC power and to
NOTE:
safety grounds. All electrical wiring must comply with applicable local 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 you are uncertain that suitable grounding is
available.
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 your system. To prevent static damage, discharge static electricity from
your body before you touch any of the electronic components, such as the microprocessor. You can do so by periodically
touching an unpainted metal surface on the chassis.
You can also take the following steps to 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 you are ready to install the component in your 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 and workbench
pads and an antistatic grounding strap.
Battery Handling Reminder
CAUTION: Danger of explosion if battery is incorrectly replaced. Replace only with
the same or equivalent type recommended by the manufacturer. Discard used
batteries according to the manufacturer's instructions.
DGS-3224TGR Gigabit Ethernet Switch User’s Guide
1
I
NTRODUCTION
This section describes the features of the DGS-3224TGR.
Features
The DGS-3224TGR was designed for departmental and enterprise connections. As an all-gigabit-port
switch, it is ideal for backbone and server connection. Powerful and versatile, the switch eliminates
network bottlenecks while giving users the capability to fine-tune performance
Switch features include:
Ports
• Twenty-four high performance 1000BASE-T ports for making 10/100/1000 connections to a
backbone, end stations, and servers.
• Four mini-GBIC (SFP) combo ports to connect fiber optic media to another switch, server or
network backbone.
• RS-232 DCE Diagnostic port (console port) for setting up and managing the Switch via a
connection to a console terminal or PC using a terminal emulation program.
Performance Features
• Store-and-forward switching scheme.
• Switching fabric: 48Gbps
• Max. Forwarding Rate: 35.7 million packets per second
• High-speed data forwarding rate of 1,488,095 pps per port at 100% of wire-speed for 1000 Mbps
speed.
• Supports 16K MAC address.
• Supports eight priority queues per port.
• Supports 2Mbytes buffer memory per switch.
• Jumbo Frame support (up to 9216 bytes).
• Multi-layer (Layer 2 to Layer 4) ACL and CoS support.
• Administrator-definable port security.
• 802.1D Spanning Tree support. Can be disabled on the entire switch or on a per-port basis.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
• 802.1Q Tagged VLAN support, including GVRP (GARP VLAN Registration Protocol).
• Support for up to 255 VLANs.
• IGMP snooping support per switch.
• Link aggregation support for up to 32 trunk groups and 8 trunk members per group.
• 802.1x port access control.
• Per-port bandwidth control.
Management
• RS-232 console port for out-of-band network management via a console terminal.
• Spanning Tree Algorithm Protocol for creation of alternative backup paths and prevention of
network loops.
• SNMP V.1, V2c1 and V3 network management, 4 groups of RMON.
• Flash memory for software upgrades. This can be done in-band via TFTP or out-of-band via the
console.
• Built-in SNMP management:
Bridge MIB (RFC 1493)
MIB-II (RFC 1213)
802.1P/Q MIB (RFC 2674)
Interface MIB (RFC 2233)
Ethernet-like MIB (RFC 1643)
Mini-RMON MIB (RFC 1757) – 4 groups. The RMON specification defines the counters for
the receive functions only. However, the DGS-3224TGR provides counters for both receive
and transmit functions.
• Supports Web-based management.
• TFTP support.
• BOOTP support.
• DHCP Client support.
• Password enabled.
• Telnet remote control console.
• Broadcast storm control.
• Multicast storm control.
• Command Line Interface support.
• Port security support.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
• SYSLOG support.
• Destination Lookup Fail control.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
2
U
NPACKING AND SETUP
This chapter provides unpacking and setup information for the switch.
Unpacking
Open the shipping carton of the switch and carefully unpack its contents. The carton should contain
the following items:
• A DGS-3224TGR 24-Port Gigabit Layer 2 Ethernet switch
• A mounting kit: 2 mounting brackets and screws
• Four rubber feet with adhesive backing
• One or two AC power cords
• A printed QIG
• A printed User’s Guide
• D-View 5.1 demo CD-ROM
• This User’s Guide with Registration Card on CD-ROM
If any item is found missing or damaged, please contact your local D-Link reseller for replacement.
Installation
Use the following guidelines when choosing a place to install the switch:
• The surface must support at least 4 kg.
• The power outlet should be within 1.82 meters (6 feet) of the device.
• Visually inspect the power cord and see that it is secured to the AC power connector.
• Make sure that there is proper heat dissipation from and adequate ventilation around the switch.
Do not place heavy objects on the switch.
Desktop or Shelf Installation
When installing the switch on a desktop or shelf, the rubber feet included with the device should first
be attached. Attach these cushioning feet on the bottom at each corner of the device. Allow adequate
space for ventilation between the device and the objects around it.
4
Figure 2-1. Installing rubber feet for desktop installation
Rack Installation
DGS-3224TGR Gigabit Ethernet Switch User’s Guide
The DGS-3224TGR can be mounted in an EIA standard-sized, 19-inch rack, which can be placed in a
wiring closet with other equipment. To install, attach the mounting brackets on the switch’s side panels
(one on each side) and secure them with the screws provided.
Figure 2- 2A. Attaching the mounting brackets
Then, use the screws provided with the equipment rack to mount the witch on the rack.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
Figure 2- 2B. Installing in an equipment rack
Power on
The switch can be used with AC power supply 100-240 VAC, 50 - 60 Hz. The switch’s power supply will
adjust to the local power source automatically and may be powered on without having any or all LAN
segment cables connected.
After the switch is plugged in, the LED indicators should respond as follows:
• All LED indicators except console will momentarily blink. This blinking of the LEDs indicates a
reset of the system.
• The console LED indicator will blink while the switch loads onboard software and performs a
self-test. When the POST is passed, the LED will become dark. If the POST fails, the indicator will
light solid amber. This indicator lights solid green when the switch is being logged-in via out-ofband/local console management through the RS-232 console port using a straight-through serial
cable.
Power Failure
As a precaution in the event of a power failure, unplug the switch. When power is resumed, plug the
switch back in.
External Redundant Power System
The switch supports an external redundant power system.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
Figure 2-3. DPS-300 in DPS-900 with DGS-3224TGR
NOTE: See the DPS-300 documentation for more information.
CAUTION: Do not use the switch with any redundant power system other than the
DPS-300.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
3
I
DENTIFYING EXTERNAL COMPONENTS
This chapter describes the front panel, rear panel, side panels, and LED indicators of the
DGS-3224TGR.
Front Panel
The front panel of the switch consists of LED indicators, an RS-232 communication port, 24
1000BASE-T ports, and 4 mini-GBIC combo ports.
Figure 3-1. Front panel view
• An RS-232 DCE console port for setting up and managing the switch via a connection to a
console terminal or PC using a terminal emulation program.
• Comprehensive LED indicators display the status of the switch and the network (see the LED
Indicators section below).
• Twenty-four 1000BASE-T Ethernet ports for 10/100/1000 connections to a backbone, end
stations, and servers.
• Four mini-GBIC combo ports to connect fiber optic media to another switch, server, or network
backbone.
Rear Panel
The rear panel of the switch contains an external Redundant Power Supply connector and an AC power
connector.
Figure 3-2. Rear panel view
• The external Redundant Power Supply connector is used to connect the DGS-3224TGR to a
DPS-300. An auto-switch circuit automatically switches to an external RPS once the internal
power supply fails. Transition from internal to external supply shall not disturb normal
operation.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
• 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. Supported input voltages range from 100 ~ 240 VAC at 50 ~ 60 Hz.
Side Panels
The right side panel of the switch contains two system fans (see the top part of the diagram below). The
left side panel contains heat vents.
Figure 3-3. Side panel views of the Switch
• The system fans are used to dissipate heat. The sides of the system also provide heat vents to
serve the same purpose. Do not block these openings, and 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.
LED Indicators
The LED indicators of the switch include Power, Console, RPS, Speed, and Link/Activity. The following
shows the LED indicators for the switch along with an explanation of each indicator.
Figure 3-4. LED indicators
• Power – This indicator on the front panel lights solid green when the system is powered up and
remains dark when the system is not powered on.
• Console – This indicator blinks green when the system is booting up. It remains solid green
when the system is operating properly. The LED is solid amber when the POST fails.
• RPS – This indicator is lit solid amber when the external Redundant Power Supply is in operation
and remains dark when it is not in use or the main power is working normally.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
• Speed – This row of indicators will light solid green when the connection speed is operating at
1000 Mbps. An unlit LED indicates a connection speed of either 10 or 100 Mbps.
• Link/Act – This row of indicators for the 24 copper ports light solid green when there is a secure
connection (or link) to a device on any of the ports. The LEDs blink green whenever there is
reception or transmission (i.e. Activity--Act) of data occurring on a port.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
4
C
ONNECTING THE SWITCH
This chapter describes how to connect the DGS-3224TGR to your Gigabit Ethernet network.
Switch to End Node
End nodes include PCs outfitted with a 10, 100, or 1000 Mbps RJ-45 Ethernet/Fast Ethernet/Gigabit
Ethernet Network Interface Card (NIC) and most routers.
An end node can be connected to the switch via a Category 3, 4, 5, or 5e UTP/STP cable—for optimal
performance, Category 5e is recommended. The end node should be connected to any of the ports of the
switch.
Figure 4-1. Switch connected to an End Node
The Link/Act LEDs light green when the link is valid. A blinking green LED indicates packet activity
on that port. The Speed LEDs indicate port speed and will light solid green for 1000 Mbps
connections. They will remain off for 10 or 100 Mbps connections.
Switch to Hub or Switch
These connections can be accomplished in a number of ways using a normal cable.
• A 10BASE-T hub or switch can be connected to the switch via a two-pair Category 3, 4, 5, or 5e
UTP/STP cable.
• A 100BASE-TX hub or switch can be connected to the switch via a two-pair Category 5 or 5e
UTP/STP cable.
• A 1000BASE-T switch can be connected to the switch via four-pair straight Category 5 or 5e
UTP/STP cable.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
Figure 4-2. Switch connected to a normal (non-Uplink) port on a hub or switch using a straight or crossover
cable
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
5
S
WITCH MANAGEMENT AND OPERATING CONCEPTS
This chapter discusses many of the concepts and features used to manage the switch, as well as the
concepts necessary for the user to understand the functioning of the switch. Further, this chapter
explains many important points regarding these features.
Configuring the switch to implement these concepts and make use of its many features is discussed in
detail in the next chapters.
Local Console Management
A local console is a terminal or a workstation running a terminal emulation program that is connected
directly to the switch via the RS-232 console port on the front of the switch. A console connection is
referred to as an ‘Out-of-Band’ connection, meaning that console is connected to the switch using a
different circuit than that used for normal network communications. So, the console can be used to set
up and manage the switch even if the network is down.
Local console management uses the terminal connection to operate the console program built-in to the
switch (see the DGS-3224TGR Command Line Interface Reference manual). A network administrator can
manage, control and monitor the switch from the console program.
The DGS-3224TGR contains a CPU, memory for data storage, flash memory for configuration data,
operational programs, and SNMP agent firmware.
Diagnostic (console) port (RS-232 DCE)
Out-of-band management requires connecting a terminal, such as a VT-100 or a PC running a terminal
emulation program (such as HyperTerminal, which is automatically installed with Microsoft Windows) a
to the RS-232 DCE console port of the switch. Switch management using the RS-232 DCE console port
is called Local Console Management to differentiate it from management performed via management
platforms, such as D-View, HP OpenView, etc.
The console port is set at the factory for the following configuration:
• Baud rate: 9,600
• Data width: 8 bits
• Parity: none
• Stop bits: 1
• Flow Control None
Make sure the terminal or PC you are using to make this connection is configured to match these
settings.
If you are having problems making this connection on a PC, make sure the emulation is set to VT-
100. If you still don’t see anything, try hitting <Ctrl> + r to refresh the screen.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
IP Addresses and SNMP Community Names
Each switch must be assigned its own IP Address, which is used for communication with an SNMP
network manager or other TCP/IP application (for example BOOTP, TFTP). The switch’s default IP
address is 10.90.90.90. You can change the default switch IP Address to meet the specification of your
networking address scheme.
The switch is also assigned a unique MAC address by the factory. This MAC address cannot be
changed, and can be found when using the command “show switch.”
In addition, you can also set an IP address for a gateway router. This becomes necessary when the
network management station is located on a different IP network from the switch, making it necessary
for management packets to go through a router to reach the network manager, and vice-versa.
For security, you can set in the switch a list of IP Addresses of the network managers that allow you to
manage the switch. You can also change the default SNMP Community Strings in the switch and set
the access rights of these Community Strings. In addition, a VLAN may be designated as a Management
VLAN.
Setting an IP Address
The IP address for the switch must be set before it can be managed with the Web-based manager. The
switch IP address may be automatically set using BOOTP or DHCP protocols, in which case the actual
address assigned to the switch must be known.
The IP address may alternatively be set using the Command Line Interface (CLI) over the
console serial port as follows:
1. Starting at the command line prompt local>, enter the commands config ipif System
ipaddress xxx.xxx.xxx.xxx/yyy.yyy.yyy.yyy. Where the x’s represent the IP address to be
assigned to the IP interface named System and the y’s represent the corresponding subnet
mask.
2. Alternatively, you can enter the commands config ipif System ipaddress
xxx.xxx.xxx.xxx/z. Where the x’s represent the IP address to be assigned to the IP
interface named System and the z represents the corresponding number of subnets in
CIDR notation.
Using this method, the switch can be assigned an IP address and subnet mask that can then be used
to connect a management station to the switch’s Web-based management agent.
Traps
Traps are messages that alert you of events that occur on the switch. The events can be as serious as a
reboot (someone accidentally turned OFF the switch), or less serious like a port status change. The
switch generates traps and sends them to the network manager (trap recipient).
Trap recipients are special users of the network who are given certain rights and access in overseeing
the maintenance of the network. Trap recipients will receive traps sent from the switch; they must
immediately take certain actions to avoid future failure or breakdown of the network.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
You can also specify which network managers may receive traps from the switch by entering a list of
the IP addresses of authorized network managers. Up to four trap recipient IP addresses, and four
corresponding SNMP community strings can be entered.
SNMP community strings function like passwords in that the community string entered for a given IP
address must be used in the management station software, or a trap will be sent.
The following are trap types the switch can send to a trap recipient:
• Cold Start –This trap signifies that the switch has been powered up and initialized such that
software settings are reconfigured and hardware systems are rebooted. A cold start is different
from a factory reset in that configuration settings saved to non-volatile RAM used to
reconfigure the switch.
• Authentication Failure – This trap signifies that someone has tried to logon to the switch
using an invalid SNMP community string. The switch automatically stores the source IP
address of the unauthorized user.
• New Root – This trap indicates that the switch has become the new root of the Spanning Tree,
the trap is sent by the switch soon after its election as the new root. This implies that upon
expiration of the Topology Change Timer the new root trap is sent out immediately after the
switch’s election as the new root.
• Topology Change (STP) – A Topology Change trap is sent by the switch when any of its
configured ports transitions from the Learning state to the Forwarding state, or from the
Forwarding state to the Blocking state. The trap is not sent if a new root trap is sent for the
same transition.
• Connected and Working – This trap is sent when the Redundant Power Supply is connected
and working.
• Disconnect or Malfunction – This trap is sent whenever the Redundant Power Supply
malfunctions.
MIBs
Management and counter information are stored in the switch in the Management Information Base
(MIB. The switch uses the standard MIB-II Management Information Base module. Consequently,
values for MIB objects can be retrieved from any SNMP-based network management software. In
addition to the standard MIB-II, the switch also supports its own proprietary enterprise MIB as an
extended Management Information Base. These MIBs may also be retrieved by specifying the MIB’s
Object-Identity (OID) at the network manager. MIB values can be either read-only or read-write.
Read-only MIBs variables can be either constants that are programmed into the switch, or variables
that change while the switch is in operation. Examples of read-only constants are the number of port
and type of ports. Examples of read-only variables are the statistics counters such as the number of
errors that have occurred, or how many kilobytes of data have been received and forwarded through a
port.
Read-write MIBs are variables usually related to user-customized configurations. Examples of these are
the switch’s IP Address, Spanning Tree Algorithm parameters, and port status.
If you use a third-party vendors’ SNMP software to manage the switch, a diskette listing the switch’s
propriety enterprise MIBs can be obtained by request. If your software provides functions to browse or
modify MIBs, you can also get the MIB values and change them (if the MIBs’ attributes permit the write
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
operation). This process however can be quite involved, since you must know the MIB OIDs and retrieve
them one by one.
SNMP
The Simple Network Management Protocol (SNMP) is an OSI layer 7 (the application layer) protocol for
remotely monitoring and configuring network devices. SNMP enables network management stations to
read and modify the settings of gateways, routers, switches, and other network devices. SNMP can be
used to perform many of the same functions as a directly connected console, or can be used within an
integrated network management software package such as HP OpenView or DView.
SNMP performs the following functions:
• Sending and receiving SNMP packets through the IP protocol.
• Collecting information about the status and current configuration of network devices.
• Modifying the configuration of network devices.
The DGS-3224TGR has a software program called an ‘agent’ that processes SNMP requests, but the
user program that makes the requests and collects the responses runs on a management station (a
designated computer on the network). The SNMP agent and the user program both use the UDP/IP
protocol to exchange packets.
Authentication
The authentication protocol ensures that both the router SNMP agent and the remote user SNMP
application program discard packets from unauthorized users. Authentication is accomplished using
‘community strings’, which function like passwords. The remote user SNMP application and the router
SNMP must use the same community string.
Packet Forwarding
The switch enters the relationship between destination MAC or IP addresses and the Ethernet port or
gateway router the destination resides on into its forwarding table. This information is then used to
forward packets. This reduces the traffic congestion on the network, because packets, instead of being
transmitted to all ports, are transmitted to the destination port only. Example: if Port 1 receives a
packet destined for a station on Port 2, the switch transmits that packet through Port 2 only, and
transmits nothing through the other ports. This process is referred to as ‘learning’ the network
topology.
MAC Address Aging Time
The Aging Time affects the learning process of the Switch. Dynamic forwarding table entries, which are
made up of the source and destination MAC addresses and their associated port numbers, are deleted
from the table if they are not accessed within the aging time.
The aging time can be from 10 to 1,000,000 seconds with a default value of 300 seconds. A very long
aging time can result in dynamic forwarding table entries that are out-of-date or no longer exist. This
may cause incorrect packet forwarding decisions by the Switch.
If the Aging Time is too short however, many entries may be aged out too soon. This will result in a high
percentage of received packets whose source addresses cannot be found in the forwarding table, in
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
which case the switch will broadcast the packet to all ports, negating many of the benefits of having a
switch.
Static forwarding entries are not affected by the aging time.
Filtering
The switch uses a filtering database to segment the network and control communication between
segments. It can also filter packets off the network for intrusion control. Static filtering entries can
be made by MAC Address filtering.
Each port on the switch is a unique collision domain and the switch filters (discards) packets whose
destination lies on the same port as where it originated. This keeps local packets from disrupting
communications on other parts of the network.
For intrusion control, whenever a switch encounters a packet originating from or destined to a MAC
address entered into the filter table, the switch will discard the packet.
Some filtering is done automatically by the switch:
• Dynamic filtering – automatic learning and aging of MAC addresses and their location on the
network. Filtering occurs to keep local traffic confined to its segment.
• Filtering done by the Spanning Tree Protocol that can filter packets based on topology,
making sure that signal loops don’t occur.
• Filtering done for VLAN integrity. Packets from a member of a VLAN (VLAN 2, for example)
destined for a device on another VLAN (VLAN 3) will be filtered.
Spanning Tree Protocol
The IEEE 802.1D Spanning Tree Protocol allows for the blocking of links between switches that form
loops within the network. When multiple links between switches are detected, a primary link is
established. Duplicated links are blocked from use and become standby links. The protocol allows for
the duplicate links to be used in the event of a failure of the primary link. Once the Spanning Tree
Protocol is configured and enabled, primary links are established and duplicated links are blocked
automatically. The reactivation of the blocked links (at the time of a primary link failure) is also
accomplished automatically – without operator intervention.
This automatic network reconfiguration provides maximum uptime to network users. However, the
concepts of the Spanning Tree Algorithm and protocol are a complicated and complex subject and must
be fully researched and understood. It is possible to cause serious degradation of the performance of
the network if the Spanning Tree is incorrectly configured. Please read the following before making any
changes from the default values.
The switch STP performs the following functions:
• Creates a single spanning tree from any combination of switching or bridging elements.
• Automatically reconfigures the spanning tree to compensate for the failure, addition, or removal
of any element in the tree.
• Reconfigures the spanning tree without operator intervention.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
STP Operation Levels
STP calculates the Bridge Identifier for each switch and then sets the Root Bridge and the Designated
Bridges.
The following are the user-configurable STP parameters for the switch level:
Parameter Description Default
Value
Bridge Identifier
(Not userconfigurable except
by setting priority
below)
Priority A relative priority for each switch –
Hello Time The length of time between
Maximum Age Timer Measures the age of a received
Forward Delay Timer The amount time spent by a port
A combination of the User-set
priority and the switch’s MAC
address. The Bridge Identifier
consists of two parts: a 16-bit
priority and a 48-bit Ethernet MAC
address
lower numbers give a higher
priority and a greater chance of a
given switch being elected as the
root bridge
broadcasts of the hello message by
the switch
BPDU for a port and ensures that
the BPDU is discarded when its
age exceeds the value of the
maximum age timer.
in the learning and listening states
waiting for a BPDU that may
return the port to the blocking
state.
32768 + MAC
32768
2 seconds
20 seconds
15 seconds
Table 5-1. STP Parameters – Switch Level
The following are the user-configurable STP parameters for the port or port group level:
Variable Description Default
Value
Port Priority A relative priority for each port –
lower numbers give a higher
priority and a greater chance of a
given port being elected as the root
port
Port Cost A value used by STP to evaluate
paths.
32768
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Table 5-2. STP Parameters – Port Group Level
Bridge Protocol Data Units
For STP to arrive at a stable network topology, the following information is used:
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
• The unique switch identifier
• The path cost to the root associated with each switch port
• The port identifier
STP communicates between switches on the network using Bridge Protocol Data Units (BPDUs). Each
BPDU contains the following information:
• The unique identifier of the switch that the transmitting switch currently believes is the root
switch
• The path cost to the root from the transmitting port
• The port identifier of the transmitting port
The switch sends BPDUs to communicate and construct the spanning-tree topology. All switches
connected to the LAN on which the packet is transmitted will receive the BPDU. BPDUs are not directly
forwarded by the switch, but the receiving switch uses the information in the frame to calculate a
BPDU, and, if the topology changes, initiates a BPDU transmission.
The communication between switches via BPDUs results in the following:
• One switch is elected as the root switch
• The shortest distance to the root switch is calculated for each switch
• A designated switch is selected. This is the switch closest to the root switch through which
packets will be forwarded to the root.
• A port for each switch is selected. This is the port providing the best path from the switch to the
root switch.
• Ports included in the STP are selected.
Creating a Stable STP Topology
If all switches have STP enabled with default settings, the switch with the lowest MAC address in the
network will become the root switch. By increasing the priority (lowering the priority number) of the
best switch, STP can be forced to select the best switch as the root switch.
When STP is enabled using the default parameters, the path between source and destination stations
in a switched network might not be ideal. For instance, connecting higher-speed links to a port that has
a higher number than the current root port can cause a root-port change. The goal is to make the
fastest link the root port.
STP Port States
The BPDUs take some time to pass through a network. This propagation delay can result in topology
changes where a port that transitioned directly from a Blocking state to a Forwarding state could create
temporary data loops. Ports must wait for new network topology information to propagate throughout
the network before starting to forward packets. They must also wait for the packet lifetime to expire for
BPDU packets that were forwarded based on the old topology. The forward delay timer is used to allow
the network topology to stabilize after a topology change. In addition, STP specifies a series of states a
port must transition through to further ensure that a stable network topology is created after a topology
change.
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DGS-3224TGR Gigabit Ethernet Switch User’s Guide
Each port on a switch using STP exists is in one of the following five states:
• Blocking – the port is blocked from forwarding or receiving packets
• Listening – the port is waiting to receive BPDU packets that may tell the port to go back to the
blocking state
• Learning – the port is adding addresses to its forwarding database, but not yet forwarding
packets
• Forwarding – the port is forwarding packets
• Disabled – the port only responds to network management messages and must return to the
blocking state first
A port transitions from one state to another as follows:
• From initialization (switch boot) to blocking
• From blocking to listening or to disabled
• From listening to learning or to blocking or to disabled
• From learning to forwarding or to blocking or to disabled
• From forwarding to blocking or to disabled
• From disabled to blocking
Figure 5-3. STP Port State Transitions
When you enable STP, every port on every switch in the network goes through the blocking state and
then transitions through the states of listening and learning at power up. If properly configured, each
port stabilizes to the forwarding or blocking state.
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