D-link DES-6000, DES-6000 User Manual
DES-6000
Modular Ethernet Switch
User’s Guide
Second Edition (April 2001)
6DES6000..02
Printed In Taiwan
RECYCLABLE
ABLE OF
T
ABOUT THIS GUIDE................................................................................................................................................................V
ONVENTIONS
C
VERVIEW OF THIS USER’S GUIDE
O
INTRODUCTION........................................................................................................................................................................1
AST ETHERNET TECHNOLOGY
F
IGABIT ETHERNET TECHNOLOGY
G
WITCHING TECHNOLOGY
S
EATURES
F
Chassis.....................................................................................................................................................................................2
Modules....................................................................................................................................................................................3
CPU Module .............................................................................................................................................................................................3
10BASE-T/100BASE-TX Module............................................................................................................................................................3
100BASE-FX (MT-RJ) Module................................................................................................................................................................4
1000BASE-T (RJ-45) Module ..................................................................................................................................................................4
1000BASE-SX (SC) Module ....................................................................................................................................................................4
1000BASE-LX (SC) Module ....................................................................................................................................................................4
Power Supply Modules .............................................................................................................................................................................4
UNPACKING AND SETUP........................................................................................................................................................6
NPACKING
U
ETUP
S
..........................................................................................................................................................................................6
ESKTOP OR SHELF INSTALLATION
D
ACK INSTALLATION
R
NSTALLING MODULES
I
ONNECTING A TERMINAL
C
OWER ON
P
Power Failure........................................................................................................................................................................10
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....................................................................................................................................................1
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ONTENTS
C
V
V
IDENTIFYING EXTERNAL COMPONENTS ......................................................................................................................11
RONT PANEL
F
IDE PANELS
S
PTIONAL PLUG-IN MODULES
O
10BASE-T/100BASE-TX Module...........................................................................................................................................12
100BASE-FX (MT-RJ) Module..............................................................................................................................................12
1000BASE-T (RJ-45) Module ................................................................................................................................................13
1000BASE-SX (MT-RJ) Gigabit Module ...............................................................................................................................13
1000BASE-SX (SC) Gigabit Module......................................................................................................................................14
1000BASE-LX (SC) Gigabit Module .....................................................................................................................................14
Power Supply Modules ..........................................................................................................................................................15
NDICATORS
LED I
CONNECTING THE SWITCH ...............................................................................................................................................16
WITCH TO END NODE
S
WITCH TO HUB OR SWITCH
S
10BASE-T Device ..................................................................................................................................................................17
100BASE-TX Device ..............................................................................................................................................................17
1000BASE-T Device ..............................................................................................................................................................17
ABLE LENGTHS
C
SWITCH MANAGEMENT CONCEPTS................................................................................................................................19
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......................................................................................................................................................................15
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........................................................................................................................................................................18
OCAL CONSOLE MANAGEMENT
L
Diagnostic (Console) Port (RS-232 DCE).............................................................................................................................19
DDRESSES AND
IP A
RAPS
T
........................................................................................................................................................................................20
MIBS.........................................................................................................................................................................................21
ACKET FORWARDING
P
Aging Time.............................................................................................................................................................................22
Filtering Database.................................................................................................................................................................22
PANNING TREE ALGORITHM
S
STA Operation Levels ............................................................................................................................................................23
On the Bridge Level................................................................................................................................................................................23
On the Port Level ....................................................................................................................................................................................23
User-Changeable STA Parameters........................................................................................................................................24
Illustration of STA..................................................................................................................................................................24
ORT TRUNKING
P
VLANS & B
MAC-based Broadcast Domains ...........................................................................................................................................27
802.1Q VLANs .......................................................................................................................................................................27
802.1Q VLAN Segmentation..................................................................................................................................................................27
Sharing Resources Across 802.1Q VLANs.............................................................................................................................................28
802.1Q VLANs Spanning Multiple Switches .........................................................................................................................................28
Port-based VLANs .................................................................................................................................................................30
ROADCAST STORMS
B
Segmenting Broadcast Domains............................................................................................................................................31
Eliminating Broadcast Storms ...............................................................................................................................................31
SNMP C
...............................................................................................................................................................22
........................................................................................................................................................................26
ROADCAST DOMAINS
.................................................................................................................................................................31
...............................................................................................................................................19
OMMUNITY NAMES
....................................................................................................................................................22
.............................................................................................................................................26
......................................................................................................................20
USING THE CONSOLE INTERFACE...................................................................................................................................32
ETTING UP
S
ONNECTING TO THE SWITCH USING TELNET
C
ONSOLE USAGE CONVENTIONS
C
IRST TIME CONNECTING TO THE SWITCH
F
User Accounts Management ..................................................................................................................................................34
Save Changes.........................................................................................................................................................................35
OGIN ON THE SWITCH CONSOLE BY REGISTERED USERS
L
Create/Modify User Accounts.................................................................................................................................................................36
User Accounts Control Table..................................................................................................................................................................37
ETTING UP THE SWITCH
S
System Configuration.............................................................................................................................................................38
Configure IP Address..............................................................................................................................................................................39
Configure Console ..................................................................................................................................................................................40
Configure Switch Modules......................................................................................................................................................................40
Configure Ports ....................................................................................................................................................................................... 42
Configure Trunk Groups .........................................................................................................................................................................44
Configure Port Mirroring ........................................................................................................................................................................45
Configure Spanning Tree Protocol.......................................................................................................................................................... 46
Configure Filtering and Forwarding Table..............................................................................................................................................49
Configure VLANs & MAC-based Broadcast Domains ..........................................................................................................................55
Update Firmware and Configuration Files ...........................................................................................................................65
System Utilities ......................................................................................................................................................................66
Ping Test ................................................................................................................................................................................................. 66
Save Settings to TFTP Server ................................................................................................................................................................. 67
Save Switch History to TFTP Server ......................................................................................................................................................68
Clear Address Table................................................................................................................................................................................ 68
Management WEB..................................................................................................................................................................................68
Community Strings and Trap Stations ...................................................................................................................................68
WITCH MONITORING
S
Network Monitoring and Device Information........................................................................................................................69
Traffic Statistics ......................................................................................................................................................................................70
Browse Address Table ............................................................................................................................................................................74
Switch History ........................................................................................................................................................................................74
A C
ONSOLE
............................................................................................................................................................32
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...........................................................................................................................................................38
................................................................................................................................................................69
Device Status ..........................................................................................................................................................................................75
Browse GVRP Status ..............................................................................................................................................................................75
Browse GMRP Status .............................................................................................................................................................................76
IP Multicast and IGMP Information .......................................................................................................................................................76
ESETTING THE SWITCH
R
Factory Reset .........................................................................................................................................................................78
Logout....................................................................................................................................................................................78
WEB-BASED NETWORK MANAGEMENT ........................................................................................................................79
NTRODUCTION
I
ETTING STARTED
G
ANAGEMENT
M
Configuration.........................................................................................................................................................................80
IP Address...............................................................................................................................................................................................81
Switch Module ........................................................................................................................................................................................81
Advanced Settings...................................................................................................................................................................................83
Port Configuration...................................................................................................................................................................................84
Trunk Groups ..........................................................................................................................................................................................85
Port Mirroring ......................................................................................................................................................................................... 86
Spanning Tree Protocol........................................................................................................................................................................... 86
Forwarding and Filtering.........................................................................................................................................................................88
IGMP ......................................................................................................................................................................................................92
VLANs & MAC-based Broadcast Domains ...........................................................................................................................................96
Management ........................................................................................................................................................................104
Community Strings and Trap Receivers ...............................................................................................................................................105
User Accounts Management .................................................................................................................................................................105
Console .................................................................................................................................................................................................106
Monitoring ...........................................................................................................................................................................107
Switch Overview................................................................................................................................................................................... 108
Port Utilization...................................................................................................................................................................................... 109
Port Traffic Statistics ............................................................................................................................................................................109
Port Error Packet Statistics....................................................................................................................................................................110
Port Packet Analysis .............................................................................................................................................................................111
Browse Address Table ..........................................................................................................................................................................113
IP Multicast & IGMP Information........................................................................................................................................................113
Browse GVRP Status ............................................................................................................................................................................114
Browse GMRP Status ...........................................................................................................................................................................114
Switch History ......................................................................................................................................................................................114
Device Status ........................................................................................................................................................................................115
Maintenance ........................................................................................................................................................................115
Firmware and Configuration Update.....................................................................................................................................................116
Save Settings to TFTP Server ............................................................................................................................................................... 117
Save Switch History to TFTP Server ....................................................................................................................................................117
Clear Address Table.............................................................................................................................................................................. 118
Save Changes ........................................................................................................................................................................................118
Factory Reset ........................................................................................................................................................................................119
Restart System ......................................................................................................................................................................................119
..........................................................................................................................................................................79
...........................................................................................................................................................................79
............................................................................................................................................................77
.....................................................................................................................................................................79
TECHNICAL SPECIFICATIONS.........................................................................................................................................120
RJ-45 PIN SPECIFICATION.................................................................................................................................................122
SAMPLE CONFIGURATION FILE .....................................................................................................................................124
Commands: ........................................................................................................................................................................................... 124
Notes about the Configuration File: ......................................................................................................................................................124
RUNTIME SOFTWARE DEFAULT SETTINGS................................................................................................................126
INDEX.......................................................................................................................................................................................127
TECHNICAL SUPPORT.........................................................................................................................................................128
WARRANTY..............................................................................................................................................................................129
REGISTRATION.......................................................................................................................................................................131
DES-6000 Modular Ethernet Switch User’s Guide
BOUT THIS
A
This User’s Guide tells you how to install your Modular Ethernet Switch, how to connect it to your Ethernet
network, and how to set its configuration using either the built-in console interface or Web-based
management.
UIDE
G
Conventions
References in this manual to the DES-6000 are frequently written simply as “Switch” or “Switches” where the
text applies to both models. Model numbers are normally used only to differentiate between specific Switches
where necessary.
Unless differentiated by model number, all information applies to both models.
Overview of this User’s Guide
♦ 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, side panels, optional plug-in
modules, and LED indicators of the Switch.
♦ Chapter 4, “Connecting the Switch.” Tells how you can connect the Switch to your Ethernet network as
well as providing an informational cable length table.
♦ Chapter 5, “Switch Management Concepts.” Talks about Local Console Management via the RS-232
DCE console port and other aspects about how to manage the Switch.
♦ Chapter 6, “Using the Console Interface.” Tells how to use the built-in console interface to change, set,
and monitor Switch performance and security.
♦ Chapter 7, “Web-Based Network Management.” Tells how to manage the Switch through an Internet
browser.
♦ Appendix A, “Technical Specifications.” Lists the technical specifications of the Switch.
♦ Appendix B, “RJ-45 Pin Specifications.” Shows the details and pin assignments for the RJ-45
receptacle/connector.
♦ Appendix C, “Sample Configuration File.”
♦ Appendix D, “Runtime Software Default Settings.”
About This Guide v
Modular Ethernet Switch User’s Guide
1
NTRODUCTION
I
This section describes the features of the Switch, as well as giving some background information about
Ethernet/Fast Ethernet, Gigabit Ethernet, and switching technology.
Fast Ethernet Technology
The growing importance of LANs and the increasing complexity of desktop computing applications are fueling
the need for high performance networks. A number of high-speed LAN technologies are proposed to provide
greater bandwidth and improve client/server response times. Among them, Fast Ethernet, or 100BASE-T,
provides a non-disruptive, smooth evolution from the current 10BASE-T technology. The dominating market
position virtually guarantees cost effective and high performance Fast Ethernet solutions in the years to
come.
100Mbps Fast Ethernet is a standard specified by the IEEE 802.3 LAN committee. It is an extension of the
10Mbps Ethernet standard with the ability to transmit and receive data at 100Mbps, while maintaining the
Carrier Sense Multiple Access with Collision Detection (CSMA/CD) Ethernet protocol.
Gigabit Ethernet Technology
Gigabit Ethernet is an extension of IEEE 802.3 Ethernet utilizing the same packet structure, format, and
support for CSMA/CD protocol, full duplex, flow control, and management objects, but with a tenfold increase
in theoretical throughput over 100Mbps Fast Ethernet and a one hundred-fold increase over 10Mbps
Ethernet. Since it is compatible with all 10Mbps and 100Mbps Ethernet environments, Gigabit Ethernet
provides a straightforward upgrade without wasting a company’s existing investment in hardware, software,
and trained personnel.
The increased speed and extra bandwidth offered by Gigabit Ethernet is essential to coping with the network
bottlenecks that frequently develop as computers and their busses get faster and more users use applications
that generate more traffic. Upgrading key components, such as your backbone and servers to Gigabit
Ethernet can greatly improve network response times as well as significantly speed up the traffic between
your subnets.
Gigabit Ethernet enables fast optical fiber connections to support video conferencing, complex imaging, and
similar data-intensive applications. Likewise, since data transfers occur 10 times faster than Fast Ethernet,
servers outfitted with Gigabit Ethernet NIC’s are able to perform 10 times the number of operations in the
same amount of time.
In addition, the phenomenal bandwidth delivered by Gigabit Ethernet is the most cost-effective method to
take advantage of today and tomorrow’s rapidly improving switching and routing internetworking
technologies. And with expected advances in the coming years in silicon technology and digital signal
processing that will enable Gigabit Ethernet to eventually operate over unshielded twisted-pair (UTP)
Introduction 1
Modular Ethernet Switch User’s Guide
cabling, outfitting your network with a powerful 1000Mbps-capable backbone/server connection creates a
flexible foundation for the next generation of network technology products.
Switching Technology
Another key development pushing the limits of Ethernet technology is in the field of switching technology. A
switch bridges Ethernet packets at the MAC address level of the Ethernet protocol transmitting among
connected Ethernet, Fast Ethernet, or Gigabit Ethernet LAN segments.
Switching is a cost-effective way of increasing the total network capacity available to users on a local area
network. A switch increases capacity and decreases network loading by making it possible for a local area
network to be divided into different segments which don’t compete with each other for network transmission
capacity, giving a decreased load on each.
The switch acts as a high-speed selective bridge between the individual segments. Traffic that needs to go
from one segment to another (from one port to another) is automatically forwarded by the switch, without
interfering with any other segments (ports). This allows the total network capacity to be multiplied, while
still maintaining the same network cabling and adapter cards.
For Fast Ethernet or Gigabit Ethernet networks, a switch is an effective way of eliminating problems of
chaining hubs beyond the “two-repeater limit.” A switch can be used to split parts of the network into
different collision domains, for example, making it possible to expand your Fast Ethernet network beyond the
205 meter network diameter limit for 100BASE-TX networks. Switches supporting both traditional 10Mbps
Ethernet and 100Mbps Fast Ethernet are also ideal for bridging between existing 10Mbps networks and new
100Mbps networks.
Switching LAN technology is a marked improvement over the previous generation of network bridges, which
were characterized by higher latencies. Routers have also been used to segment local area networks, but the
cost of a router and the setup and maintenance required make routers relatively impractical. Today’s
switches are an ideal solution to most kinds of local area network congestion problems.
Features
The DES-6000 Modular switch is designed for easy installation and high performance in an environment
where traffic on the network and the number of users increases continuously.
Switch features include:
Chassis
The chassis is the main unit that modules and power supplies are installed into. A CPU module and a power
supply module come preinstalled in the chassis.
Chassis features include:
♦ Eight slots for installing networking modules (plus one slot reserved for the CPU)
♦ Two slots for installing redundant power supply modules
♦ 21.3 Gigabit/sec. (Gbps) backplane switching fabric
♦ Hot-swappable design for power supply modules
♦ Networking modules warm-swappable (except CPU module)
2 Introduction
Modular Ethernet Switch User’s Guide
♦ Ears and screws for rack mounting
Modules
The following describes the optional plug-in modules available for the switch.
CPU Module
♦ A single CPU module must be present and must be installed in first (uppermost) slot.
♦ Layer 2 switching based on MAC address & VLAN ID.
♦ Store and Forward packet switching.
♦ Broadcast Storm rate filtering.
♦ Supports static filtering (based on MAC address).
♦ Supports IEEE 802.1Q VLAN (Static VLAN).
♦ Proprietary simplified Port-based VLANs
♦ IEEE 802.1d Spanning Tree support.
♦ Address table: 12K MAC address per switch
♦ 96 Static VLAN Entries (in IEEE 802.1Q VLANs mode)
♦ Supports 802.1p priority queuing (2 priority queues)
♦ Port Aggregation (Port-Trunking) Capability
♦ Port Mirroring
♦ IGMP snooping
♦ Head Of Line (HOL) Blocking Prevention
♦ RS-232 port for out-of-band management and system configuration
♦ Telnet Remote Configuration
♦ TFTP software upgrades, settings file and switch log uploads
♦ Web-based management
♦ SNMP Agents:
♦ MIB-II (RFC 1213)
♦ RMON MIB (RFC 1757)
♦ Bridge MIB (RFC 1493)
♦ SLIP
♦ Supports four RMON (1,2,3,9) groups
♦ Port Security
♦ BootP support
♦ Support for DHCP Client
10BASE-T/100BASE-TX Module
♦ 16 10BASE-T/100BASE-TX ports
♦ Fully compliant with IEEE 802.3 10BASE-T, IEEE 802.3u
100BASE-TX
♦ All 10/100Mbps ports support NWay auto-negotiation
♦ Back pressure Flow Control support for Half-duplex mode
Introduction 3
Modular Ethernet Switch User’s Guide
♦ IEEE 802.3x-compliant Flow Control support for Full-duplex
♦ Per port packet buffer: 0.5 Mbytes
100BASE-FX (MT-RJ) Module
♦ 12 100BASE-FX (MT-RJ) Fast Ethernet ports
♦ Fully compliant with IEEE 802.3u 100BASE-FX
♦ Back pressure Flow Control support for Half-duplex mode
♦ IEEE 802.3x compliant Flow Control support for Full-duplex
♦ Per port packet buffer: 0.5 Mbytes
1000BASE-T (RJ-45) Module
♦ 2-port, front-panel module
♦ Store and forward packet switching
♦ Connects to 1000BASE-T devices only at full-duplex and auto-negotiating.
♦ 2 1000BASE-T (RJ-45) Gigabit Ethernet ports
♦ Fully compliant with IEEE 802.3ab
♦ Fully compliant with IEEE 802.1Q/P
♦ Back pressure Flow Control support for Half-duplex mode
♦ IEEE 802.3x compliant Flow Control support for Full-duplex
1000BASE-SX (SC) Module
♦ 2 1000BASE-SX (SC) Gigabit Ethernet ports
♦ Fully compliant with IEEE 802.3z
♦ Support Full-duplex operation only
♦ IEEE 802.3x-compliant Flow Control support
♦ Per port packet buffer: 2 Mbytes
1000BASE-LX (SC) Module
♦ 2 1000BASE-LX (SC) Gigabit Ethernet ports
♦ Fully compliant with IEEE 802.3z
♦ Support Full-duplex operation only
♦ IEEE 802.3x-compliant Flow Control support
♦ Per port packet buffer: 2 Mbytes
Power Supply Modules
♦ Dual power modules design
♦ Current sharing design
♦ Full redundant feature design to ensure continuous operation
♦ If one power module fails, the other will take over all current supply automatically.
♦ Hot-swappable/Hot-pluggable
♦ Power management functions enabled
♦ Revolving handle design
4 Introduction
♦ Input: 90 ~ 264 VAC, 47 ~ 63Hz
♦ Output: 3.3V: 4A ~ 60A
♦ 12V: 0.1A ~ 2A
Modular Ethernet Switch User’s Guide
Introduction 5
Modular Ethernet Switch User’s Guide
2
NPACKING AND SETUP
U
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:
♦ One switch chassis
♦ One management module (pre-installed in uppermost slot)
♦ One power supply module (pre-installed)
♦ One mounting kit: four mounting brackets and screws
♦ Four rubber feet with adhesive backing
♦ One AC power cord
♦ One console cable
♦ One printed copy of the quickstart guide
♦ One printed copy of this user’s guide
♦ One CD-ROM containing this user’s guide
If any item is found missing or damaged, please contact your local reseller for replacement.
Setup
The setup of the Switch can be performed using the following steps:
♦ The surface must support at least 5 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 fully 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.
6 Unpacking and Setup
Modular Ethernet Switch User’s Guide
Desktop or Shelf Installation
When installing the Switch on a desktop or shelf, the rubber feet included with the device must be first
attached. Attach these cushioning feet on the bottom at each corner of the device. Allow enough ventilation
space between the device and the objects around it.
Figure 2-1. Switch installed on a Desktop or Shelf
Rack Installation
The Switch can be mounted in an EIA standard size, 19-inch rack, which can be placed in a wiring closet with
other equipment. To install, attach the mounting brackets on the Switch’s front panel (one on each side) and
secure them with the screws provided.
Figure 2-2. Attaching the mounting brackets to the Switch
Then, use the screws provided with the equipment rack to mount the Switch in the rack.
Unpacking and Setup 7
Modular Ethernet Switch User’s Guide
Installing Modules
The DES-6000 supports up to 9 modules which can be installed into the module bays. Networking modules
are warm-swappable, meaning they can be added and removed while power to the switch is ON. After warmswapping a networking module, the switch will automatically be rebooted. Make sure to use the Save
Changes command to save the current configuration to NV-RAM before warm-swapping modules. The CPU
module, however, is NOT hot-swappable. Removing or inserting the CPU module while the power is on may
cause irreparable damage to the module and/or to the Switch itself. Further, make sure you have unplugged
the power cord from the removable power supply module before inserting or removing it from the Switch.
CAUTION: Due to the high energy present in this system, extreme caution should be
exercised whenever adding or removing system components. No element of this system
may be installed or removed except by an authorized technician.
Figure 2-3. Removing a Blank Slot Cover
Modules can be installed into any free slot, except the CPU module which must be installed in the uppermost
(top) slot. To install a module, simply remove a blank slot cover and slide the module along the guide rails
until it snaps firmly in place.
8 Unpacking and Setup
Modular Ethernet Switch User’s Guide
Figure 2–4. Installing a Module
Connecting a Terminal
The DES-6000 can perform basic switching functions without special configuration, but to use the Switch’s
advanced features you must first configure the unit through a terminal (a VT-100 serial data terminal or a
computer running a VT-100 emulator). The connection is made through the Switch’s Diagnostic RS-232 port,
which is configured at the factory as follows:
♦ Baud Rate: 9600
♦ Data Bits: 8
♦ Parity: none
♦ Stop Bits: 1
♦ Flow Control: None
The RS-232 port has a nine-socket D-shell connector with IBM-type DCE wiring, and can be connected to the
terminal using an off-the-shelf RS-232 cable with the proper connectors for the terminal and the DES-6000.
Power on
Power up the DES-6000 as follows:
1. Make sure the power module is properly installed in the device.
2. Plug the device end of the supplied power cord firmly into the power inlet on the DES-6000’s front
panel of the redundant power supply.
3. Plug the outlet end of the power cord firmly into a suitable AC outlet.
4. Observe the DES-6000’s LED indicators to make sure the Switch is operating correctly.
The DES-6000’s LED indicators operate as follows during a normal power-up:
Unpacking and Setup 9
Modular Ethernet Switch User’s Guide
♦ All indicators blink momentarily to indicate a system reset.
♦ The Power indicator flashes for about 20 seconds while the switch prepares its run-time software and
performs a self-test.
♦ The Power indicator begins shining steadily, and the remaining indicators begin reflecting port and
system status.
Power Failure
As a precaution, the Switch should be unplugged in case of an impending power failure. When power is
resumed, plug the Switch back in.
10 Unpacking and Setup
Modular Ethernet Switch User’s Guide
3
DENTIFYING EXTERNAL
I
This chapter describes the front panel, side panels, optional plug-in modules, and LED indicators of the
Switch
OMPONENTS
C
Front Panel
The front panel of the Switch consists nine slide-in module slots for networking modules, two slide-in module
slots for power supply modules, an RS-232 communication port, and LED indicators.
Figure 3-1. Front panel view of the Switch
♦ Comprehensive LED indicators display the conditions of the Switch and status of the network. A
description of these LED indicators follows (see LED Indicators).
♦ An RS-232 DCE console port is used to diagnose the Switch via a connection to a terminal (or PC) and
Local Console Management.
♦ Nine slide-in module slots installing networking modules and the CPU module.
♦ Two slide-in module slots for installing power supply modules.
Side Panels
The left side panel of the Switch contains four system fans. The right side panel contains heat vents.
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 adequate 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.
Identifying External Components 11
Modular Ethernet Switch User’s Guide
Optional Plug-in Modules
The DES-6000 Modular Ethernet Switch is able to accommodate a range of plug-in modules in order to
increase functionality and performance.
10BASE-T/100BASE-TX Module
Figure 3-2. 16-port, 10/100BASE-TX module
♦ 16-port, front-panel module.
♦ Connects to 10BASE-T and 100BASE-TX devices at full- or half-duplex.
♦ Supports Category 3, 4, 5 or better UTP or STP connections of up to 100 meters each.
100BASE-FX (MT-RJ) Module
Figure 3-3. 12-port, 100BASE-FX (MT-RJ) module
♦ 12-port, front-panel module.
♦ Connects to 100BASE-FX devices at full- or half-duplex.
♦ 12 100BASE-FX (MT-RJ) Fast Ethernet ports
12 Identifying External Components
Modular Ethernet Switch User’s Guide
♦ Fully compliant with IEEE 802.3u 100BASE-FX
♦ Back pressure Flow Control support for Half-duplex mode
♦ IEEE 802.3x compliant Flow Control support for Full duplex
♦ Per port packet buffer: 0.5 Mbytes
♦ Supports multi-mode fiber-optic cable connections of up to 412 meters in half-duplex or 2 km in full-duplex
mode.
1000BASE-T (RJ-45) Module
Figure 3-4. 2-port, 1000BASE-T (RJ-45) module
♦ 2-port, front-panel module
♦ Store and forward packet switching
♦ Connects to 1000BASE-T devices only at full-duplex and auto-negotiating.
♦ 2 1000BASE-T (RJ-45) Gigabit Ethernet ports
♦ Fully compliant with IEEE 802.3ab
♦ Fully compliant with IEEE 802.1Q/P
♦ Back pressure Flow Control support for Half-duplex mode
♦ IEEE 802.3x compliant Flow Control support for Full-duplex
1000BASE-SX (MT-RJ) Gigabit Module
Figure 3-5. Two-port, 1000BASE-SX (MT-RJ) module
♦ Two-port, front panel module.
♦ Connects to a 1000BASE-SX device at full duplex.
Identifying External Components 13
Modular Ethernet Switch User’s Guide
♦ 2 1000BASE-SX (MT-RJ) Gigabit Ethernet ports
♦ Fully compliant with IEEE 802.3z
♦ Supports Full-duplex operation only
♦ IEEE 802.3x-compliant Flow Control support
♦ Per port packet buffer: 2 Mbytes
1000BASE-SX (SC) Gigabit Module
Figure 3-6. Two-port, 1000BASE-SX gigabit module
♦ Two-port, front-panel module.
♦ Connects to 1000BASE-SX devices at full duplex.
♦ 2 1000BASE-SX (SC) Gigabit Ethernet ports
♦ Fully compliant with IEEE 802.3z
♦ Support Full-duplex operation only
♦ IEEE 802.3x-compliant Flow Control support
♦ Per port packet buffer: 2 Mbytes
1000BASE-LX (SC) Gigabit Module
Figure 3-7. Two-port, 1000BASE-LX gigabit module
♦ Two-port, front-panel module.
♦ Connects to 1000BASE-LX devices at full duplex.
♦ 2 1000BASE-LX (SC) Gigabit Ethernet ports
♦ Fully compliant with IEEE 802.3z
♦ Supports full-duplex operation only
♦ IEEE 802.3x-compliant Flow Control support
♦ Per port packet buffer: 2 Mbytes
14 Identifying External Components
Modular Ethernet Switch User’s Guide
Power Supply Modules
♦ Dual power modules design with current sharing design
♦ Full redundant feature design to ensure continuous operation
♦ If one power module failed, the other will take over all current supply automatically.
♦ Hot-swappable/Hot-pluggable capability
♦ Power management functions
♦ Input: 90 ~ 264 VAC, 47 ~ 63Hz
♦ Output: 3.3V: 4A ~ 60A
♦ 12V: 0.1A ~ 2A
LED Indicators
The LED indicators of the Switch include CPU Status, Console, Power OK, and Utilization. The following
shows the LED indicators for the Switch along with an explanation of each indicator.
Figure 3-8. The Switch LED indicators
♦ CPU Status This leftmost indicator on the front panel displays the current status of the switch. The
LED will blink while the Power-On Self-Test (POST) is running during startup. It will light a steady
green after the POST test to indicate the switch is powered on and operating properly. It will light
amber when an error occurs during startup and the switch is therefore not functioning.
♦ Console This indicator is lit green when the switch is being managed through the embedded console
management program. The console program is accessed either through the out-of-band RS-232 console
port using a straight-through serial cable or in-band via Telnet. When a secured connection is
established, this LED is lit. The indicator blinks when the console RS-232 is accessed.
♦ Power OK This indicator lights green when the CPU module of the switch is receiving power and
functioning properly.
♦ Utilization These indicators display the percentage of utilization on the CPU in the switch.
Identifying External Components 15
Modular Ethernet Switch User’s Guide
4
ONNECTING THE SWITCH
C
This chapter describes how to connect the Switch to your Ethernet network as well as providing an
informational cable length table.
Switch to End Node
End nodes include PCs outfitted with a Network Interface Card (NIC) and most routers. For twisted-pair
(copper) connections, the RJ-45 UTP ports on NICs and most routers are MDI-II. When using a normal
straight-through cable, an MDI-II port must connect to an MDI-X port.
An end node can be connected to the Switch via a two-pair Category 3, 4, 5 UTP/STP straight cable (be sure to
use Category 5 UTP or STP cabling for 100BASE-TX Fast Ethernet connections). The end node should be
connected to any of the sixteen ports (1x - 16x) on the 10BASE-T/100BASE-TX module. The LED indicators
for the port the end node is connected to are lit according to the capabilities of the NIC. If LED indicators are
not illuminated after making a proper connection, check the PC’s LAN card, the cable, switch conditions, and
connections.
The following LED indicator states are possible for an end node to switch connection:
1. The 100M indicator comes ON for a 100 Mbps and stays OFF for 10 Mbps.
2. The Link/Act indicator lights up upon hooking up a PC that is powered on.
Switch to Hub or Switch
These connections can be accomplished in a number of ways. For twisted-pair (copper) connections, the most
important consideration is that when using a normal, straight-through cable, the connection should be made
between a normal crossed port (Port 1x, 2x, etc.) and an Uplink (MDI-II) port. If you are using a crossover
cable, the connection can be made from a normal crossed port to another crossed port.
♦ A 10BASE-T hub or switch can be connected to the Switch via a two-pair Category 3, 4 or 5 UTP/STP
straight cable.
♦ A 100BASE-TX hub or switch can be connected to the Switch via a four-pair Category 5 UTP/STP
straight cable.
If the other switch or hub contains an unused Uplink port, we suggest connecting the other device’s Uplink
(MDI-II) port to any of the switch’s (MDI-X) ports (1x - 16x 100BASE-TX ports).
If the other device does not have an unused Uplink port, make the connection with a crossover cable from any
of the twisted-pair ports on the switch to any normal twisted-pair port on the hub.
16 Connecting The Switch
Modular Ethernet Switch User’s Guide
10BASE-T Device
For a 10BASE-T device, the Switch’s LED indicators should display the following:
♦ 100M speed indicator is OFF.
♦ Link/Act indicator is ON.
100BASE-TX Device
For a 100BASE-TX device, the Switch’s LED indicators should display the following:
♦ 100M speed indicator is ON.
♦ Link/Act indicator is ON.
1000BASE-T Device
For a 1000BASE-T device, the Switch’s LED indicators should display the following:
♦ Link/Act indicator is ON.
Connecting The Switch 17
Modular Ethernet Switch User’s Guide
Cable Lengths
Standard
1000BASE-SX
1000BASE-LX
1000BASE-T
100BASE-FX
100BASE-TX
10BASE-T
Media Type
50/125µm Multimode Fiber 400 500 Meters
50/125µm Multimode Fiber 500 550 Meters
62.5/125µm Multimode Fiber 160 220 Meters
62.5/125µm Multimode Fiber 200 275 Meters
50/125µm Multimode Fiber 400 500 Meters
50/125µm Multimode Fiber 500 550 Meters
62.5/125µm Multimode Fiber 500 550 Meters
10µ Single-mode Fiber 5000 Meters
Category 5e UTP Cable
(1000Mbps)
50/125µm Multimode Fiber
(half-duplex operation)
50/125µm Multimode Fiber
(full-duplex operation)
62.5/125µm Multimode Fiber
(half-duplex operation)
52.5/125µm Multimode Fiber
(full-duplex operation)
Category 5 UTP Cable
(100Mbps)
Category 3 UTP Cable
(10Mbps)
MHz/km
Rating
100 Meters
400 Meters
2000 Meters
400 Meters
2000 Meters
100 Meters
100 Meters
Maximum
Distance
18 Connecting The Switch
Modular Ethernet Switch User’s Guide
5
WITCH
S
This chapter discusses many of the features used to manage the switch, and explains many concepts and
important points regarding these features. Configuring the Switch to implement these concepts is discussed
in detail in the next chapters.
ANAGEMENT
M
ONCEPTS
C
Local Console Management
Local console management involves the administration of the Switch via a direct connection to the RS-232
DCE console port. This is an Out-Of-Band connection, meaning that it is on a different circuit than normal
network communications, and thus works even when the network is down.
The local console management connection involves a terminal or PC running terminal emulation software to
operate the Switch’s built-in console program (see Chapter 6, “Using the Console Interface”). Using the console
program, a network administrator can manage, control and monitor the many functions of the Switch.
Hardware components in the Switch allow it to be an active part of a manageable network. These components
include a CPU, memory for data storage, other related hardware, and SNMP agent firmware. Activities on
the Switch can be monitored with these components, while the Switch can be manipulated to carry out
specific tasks.
Diagnostic (Console) Port (RS-232 DCE)
Out-of-band management requires connecting a terminal, such as a VT-100 or a PC running 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 done via management platforms, such as
IBM NetView, HP OpenView, etc.
The console port is set 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 or
ANSI. If you still don’t see anything, try hitting <Ctrl> + r to refresh the screen.
Switch Management Concepts 19
Modular Ethernet Switch User’s Guide
IP Addresses and SNMP Community Names
Each Switch has its own IP Address, which is used for communication with an SNMP network manager or
other TCP/IP application (for example BOOTP, TFTP, etc.). You must provide the switch with an IP Address
to meet the specification of your networking address scheme.
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 as 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 you allow to
manage the Switch. You can also change the default Community Name in the Switch and set access rights of
these Community Names.
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 managers). The following lists the types of events that
can take place on the Switch.
◊ System resets
◊ Errors
◊ Status changes
◊ Topology changes
◊ Operation
You can also specify which network managers may receive traps from the Switch by setting a list of IP
Addresses of the authorized network managers.
Trap managers are special users of the network who are given certain rights and access in overseeing the
maintenance of the network. Trap managers will receive traps sent from the Switch; they must immediately
take certain actions to avoid future failure or breakdown of the network.
The following are trap types a trap manager will receive:
♦ 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.
♦ Warm Start This trap signifies that the Switch has been rebooted, however the Power-On Self-Test
(POST) is skipped.
♦ Authentication Failure This trap signifies that someone has tried to logon to the switch using an
invalid SNMP community name. 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 a bridge 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 selection as a new
root.
♦ Topology Change 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.
20 Switch Management Concepts
Modular Ethernet Switch User’s Guide
♦ Link Change Event This trap is sent whenever the link of a port changes from link up to link down
or from link down to link up.
♦ Port Partition This trap is sent whenever a port is partitioned as a result of more than sixty-one
collisions on the port (i.e., is automatically partitioned). The number of collisions that triggers this trap
is the same at either 10Mbps or 100Mbps.
♦ Broadcast Storm This trap is sent whenever the port reaches the broadcast storm rising or falling
threshold.
♦ Power Supply Module Inserted This trap is sent whenever a redundant power supply module is
installed in the switch.
♦ Power Supply Module Removed This trap is sent whenever a redundant power supply module is
removed in the switch.
♦ Bad Power This trap is sent whenever a redundant power supply is receiving AC power but not
supplying DC power to the switch.
♦ Power Supply Module Inserted This trap is sent whenever a redundant power supply is installed in
the switch.
♦ Power Supply Module Temperature Warning This trap is sent whenever the temperature of a
redundant power supply module measures over 80° C (176° F).
♦ Power Supply Module Voltage Warning This trap is sent whenever a redundant power supply
generates DC current over 3.9 volts.
♦ Power Supply Module Current Warning This trap is sent whenever a redundant power supply
generates DC current over 60 amps.
♦ System Fan Failure This trap is sent whenever one of the four system fans in the switch fails.
♦ Power Fan1 Failure This trap is sent whenever one of the two fans on a redundant power supply
module fails.
♦ Power Fan2 Failure This trap is sent whenever one of the two fans on a redundant power supply
module fails.
MIBs
Management information and counters 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 manager software. In addition to the standard MIBII, 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 ports and types
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 operation).
This process however can be quite involved, since you must know the MIB OIDs and retrieve them one by
one.
Switch Management Concepts 21
Modular Ethernet Switch User’s Guide
Packet Forwarding
The Switch learns the network configuration and uses this information to forward packets. This reduces the
traffic congestion on the network, because packets, instead of being transmitted to all segments, are
transmitted to the destination 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.
Aging Time
The Aging Time is a parameter that affects the auto-learn process of the Switch in terms of the network
configuration. Dynamic Entries, which make up the auto-learned-node address, are aged out of the address
table according to the Aging Time that you set.
The Aging Time can be from 10 seconds to 9999 seconds. A very long Aging Time can result with the out-ofdate Dynamic Entries that may cause incorrect packet filtering/forwarding decisions.
On the other hand, if the Aging Time is too short, many entries may be aged out soon, resulting in a high
percentage of received packets whose source addresses cannot be found in the address table, in which case the
Switch will broadcast the packet to all ports, negating many of the benefits of having a switch.
Filtering Database
A switch uses a filtering database to segment the network and control communications between segments.
It also filters packets off the network for intrusion control (MAC Address filtering).
For port 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 defined by the user, the switch will discard the packet.
Filtering includes:
1. 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.
2. MAC address filtering The manual entry of specific MAC addresses to be filtered from the network.
3. Filtering done by the Spanning Tree Protocol Can filter packets based on topology, making sure
that signal loops don’t occur.
4. 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 Algorithm
The Spanning Tree Algorithm (STA) in the Switch allows you to create alternative paths (with multiple
switches or other types of bridges) in your network. These backup paths are idle until the Switch determines
that a problem has developed in the primary paths. When a primary path is lost, the switch providing the
alternative path will automatically go into service with no operator intervention. This automatic network
reconfiguration provides maximum uptime to network users. The concept of the Spanning Tree Algorithm is a
22 Switch Management Concepts
Modular Ethernet Switch User’s Guide
complicated and complex subject and must be fully researched and understood. Please read the following
before making any changes.
♦ Network loop detection and prevention With STA, there will be only one path between any two
LANs. If there is more than one path, forwarded packets will loop indefinitely. STA detects any looped
path and selects the path with the lowest path cost as the active path, while blocking the other path
and using it as the backup path.
♦ Automatic topology re-configuration When the path for which there is a backup path fails, the
backup path will be automatically activated, and STA will automatically re-configure the network
topology.
STA Operation Levels
STA operates on two levels: the bridge level and the port level. On the bridge level, STA calculates the Bridge
Identifier for each Switch, then sets the Root Bridge and the Designated Bridges. On the port level, STA sets
the Root Port and Designated Ports. Details are as follows:
On the Bridge Level
♦ Root Bridge The switch with the lowest Bridge Identifier is the Root Bridge. Naturally, you will want
the Root Bridge to be the best switch among the switches in the loop to ensure the highest network
performance and reliability.
♦ Bridge Identifier This is the combination of the Bridge Priority (a parameter that you can set) and
the MAC address of the switch. Example: 4 00 80 c8 00 01 00, where 4 is the Bridge Priority. A lower
Bridge Identifier results in a higher priority for the switch, and thus increases it probably of being
selected as the Root Bridge.
♦ Designated Bridge From each LAN segment, the attached Bridge that has the lowest Root Path Cost
to the Root Bridge is the Designated Bridge. It forwards data packets for that LAN segment. In cases
where all Switches have the same Root Path Cost, the switch with the lowest Bridge Identifier becomes
the Designated Bridge.
♦ Root Path Cost The Root Path Cost of a switch is the sum of the Path Cost of the Root Port and the
Root Path Costs of all the switches that the packet goes through. The Root Path Cost of the Root Bridge
is zero.
♦ Bridge Priority This is a parameter that users can set. The smaller the number you set, the higher
the Bridge Priority is. The higher the Bridge Priority, the better the chance the Switch will be selected
as the Root Bridge.
On the Port Level
♦ Root Port Each switch has a Root Port. This is the port that has the lowest Path Cost to the Root
Bridge. In case there are several such ports, then the one with the lowest Port Identifier is the Root
Port.
♦ Designated Port This is the port on each Designated Bridge that is attached to the LAN segment for
which the switch is the Designated Bridge.
♦ Port Priority The smaller this number, the higher the Port Priority is. With higher Port Priority, the
higher the probability that the port will be selected as the Root Port.
♦ Path Cost This is a changeable parameter and may be modified according to the STA specification.
The 1000Mbps segment has an assigned Path Cost of 4, the 100Mbps segment has an assigned Path
Cost of 19, and each 10Mbps segment has an assigned Path Cost of 100, based on the STA
specifications.
Switch Management Concepts 23
Modular Ethernet Switch User’s Guide
User-Changeable STA Parameters
The factory default setting should cover the majority of installations. However, it is advisable to keep the
default settings as set at the factory, unless it is absolutely necessary. The user changeable parameters in the
Switch are as follows:
♦ Bridge Priority A Bridge Priority can be from 0 to 65535. 0 is equal to the highest Bridge Priority.
♦ Bridge Hello Time The Hello Time can be from 1 to 10 seconds. This is the interval between two
transmissions of BPDU packets sent by the Root Bridge to tell all other Switches that it is indeed the
Root Bridge. If you set a Hello Time for your Switch, and it is not the Root Bridge, the set Hello Time
will be used if and when your Switch becomes the Root Bridge.
Note: The Hello Time cannot be longer than the Max. Age. Otherwise, a configuration error will
occur.
♦ Bridge Max. Age The Max. Age can be from 6 to 40 seconds. At the end of the Max. Age, if a BPDU
has still not been received from the Root Bridge, your Switch will start sending its own BPDU to all
other Switches for permission to become the Root Bridge. If it turns out that your Switch has the lowest
Bridge Identifier, it will become the Root Bridge.
♦ Bridge Forward Delay The Forward Delay can be from 4 to 30 seconds. This is the time any port on
the Switch spends in the listening state while moving from the blocking state to the forwarding state.
Observe the following formulas when you set the above parameters:
1. Max. Age ≤ 2 x (Forward Delay - 1 second)
2. Max. Age ≥ 2 x (Hello Time + 1 second)
♦ Port Priority A Port Priority can be from 0 to 255. The lower the number, the greater the probability
the port will be chosen as the Root Port.
Illustration of STA
A simple illustration of three Bridges (or the Switch) connected in a loop is depicted in Figure 5-1. In this
example, you can anticipate some major network problems if the STA assistance is not applied. For instance,
if Bridge 1 broadcasts a packet to Bridge 2, Bridge 2 will broadcast it to Bridge 3, and Bridge 3 will broadcast
it to Bridge 1 and so on. The broadcast packet will be passed indefinitely in a loop, causing a serious network
failure.
To alleviate network loop problems, STA can be applied as shown in Figure 5-2. In this example, STA breaks
the loop by blocking the connection between Bridge 1 and 2. The decision to block a particular connection is
based on the STA calculation of the most current Bridge and Port settings. Now, if Bridge 1 broadcasts a
packet to Bridge 3, then Bridge 3 will broadcast it to Bridge 2 and the broadcast will end there.
STA setup can be somewhat complex. Therefore, you are advised to keep the default factory settings and STA
will automatically assign root bridges/ports and block loop connections. However, if you need to customize the
STA parameters, refer to Table 5-1.
24 Switch Management Concepts
Modular Ethernet Switch User’s Guide
Figure 5-1. Before Applying the STA Rules
Figure 5-2. After Applying the STA Rules
STA parameters Settings Effects Comment
Bridge Priority
Hello Time
Max. Age Time
Forward Delay
Port Level STA parameters
Enable/Disable
Port Priority
lower the #,
higher the
priority
1 - 10 sec. No effect, if not
6 - 40 sec. Compete for Root
4 - 30 sec. High # delays the
Enable/
Disable
lower the #,
higher the
priority
Increases chance of
becoming the Root
Bridge
Root Bridge
Bridge, if BPDU is
not received
change in state
Enable or disable
this LAN segment
Increases chance of
become Root Port
Avoid, if the switch is
used in workgroup
level of a large network
Never set greater than
Max. Age Time
Avoid low number for
unnecessary reset of
Root Bridge
Max. Age ≤ 2 x
(Forward Delay - 1)
Max. Age ≥ 2 x (Hello
Time + 1)
Disable a port for
security or problem
isolation
Table 5-1. User-selective STA parameters
Switch Management Concepts 25
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