Dell PowerConnect 2708 User manual

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Dell™ PowerConnect™ 27XX
Systems
User’s Guide

Notes, Notices, and Cautions
NOTE: A NOTE indicates important information that helps you make better use of your computer.
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.
___________________
Information in this document is subject to change without notice.
© 2006 Dell Inc. All rights reserved.
Reproduction in any manner whatsoever without the written permission of Dell Inc. is strictly forbidden.
Trademarks used in this text: Dell, Dell OpenManage, the DELL logo, and PowerConnect are trademarks of Dell Inc. Microsoft is a registered
trademark 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.
Dell Inc. disclaims any proprietary interest in trademarks and trade names other than its own.
Models PC2708, PC2716, PC2724, PC2748
October 2006

Contents 3
Contents
1 Introduction
System Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7
8 1-Gigabit Ethernet Ports . . . . . . . . . . . . . . . . . . . . . . . 7
16 1-Gigabit Ethernet Ports . . . . . . . . . . . . . . . . . . . . . . 8
24 1-Gigabit Ethernet Ports + 2 SFP Combo ports . . . . . . . . . . . . 8
48 1-Gigabit Ethernet Ports . . . . . . . . . . . . . . . . . . . . . . 8
Features. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
General Features . . . . . . . . . . . . . . . . . . . . . . . . . . . 9
MAC Address Supported Features . . . . . . . . . . . . . . . . . . . 11
Layer 2 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . 11
VLAN Supported Features . . . . . . . . . . . . . . . . . . . . . . . 12
Class of Service (CoS) Features . . . . . . . . . . . . . . . . . . . . 12
Ethernet Switch Management Features . . . . . . . . . . . . . . . . 13
Port Default Settings . . . . . . . . . . . . . . . . . . . . . . . . . 13
2 Hardware Description
Switch Port Configurations. . . . . . . . . . . . . . . . . . . . . . . . . 15
PowerConnect 2708/2716/2724/2748 Front Panel Port Description . . . . 15
Physical Dimensions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
LED Definitions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Power LED . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19
Managed Mode LED. . . . . . . . . . . . . . . . . . . . . . . . . . 19
Fan LED (2748 only) . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Port LEDs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Managed Mode Button . . . . . . . . . . . . . . . . . . . . . . . . 21
Switch Ventilation Fan. . . . . . . . . . . . . . . . . . . . . . . . . 22
Cables, Port Connections, and Pinout Information . . . . . . . . . . . . . . 22
1000BASE-T Cable Requirements . . . . . . . . . . . . . . . . . . . 22
RJ-45 Connections for 10/100/1000BASE-T Ports . . . . . . . . . . . . 22
SFP Ports . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Pin Connections for SFP Interfaces . . . . . . . . . . . . . . . . . . 24

4Contents
Power Connectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Internal Power Supply Connector . . . . . . . . . . . . . . . . . . . 24
3 Installing the Dell™ PowerConnect™ 27XX
Installation Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Site Requirements . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Unpacking. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Safety . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
Handling Static Sensitive Devices . . . . . . . . . . . . . . . . . . . 27
Package Contents. . . . . . . . . . . . . . . . . . . . . . . . . . . 27
Unpacking the Device . . . . . . . . . . . . . . . . . . . . . . . . . 27
Mounting the Device. . . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Installation Precautions . . . . . . . . . . . . . . . . . . . . . . . . . . 28
Installing the Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . 29
Installing the Device in a Rack . . . . . . . . . . . . . . . . . . . . . 29
Installing the Device on a Flat Surface . . . . . . . . . . . . . . . . . 30
Connecting the Device to AC Power Supply . . . . . . . . . . . . . . 31
Connecting the Device to the Network . . . . . . . . . . . . . . . . . . . 32
4 Starting and Configuring the Dell™ PowerConnect™ 27XX
Viewing Switch Operation . . . . . . . . . . . . . . . . . . . . . . . . . 33
Initial Configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
5 Using the Dell™ OpenManage™ Switch Administrator
Understanding the Interface . . . . . . . . . . . . . . . . . . . . . . . . 37
Using the OpenManage Switch Administrator Buttons . . . . . . . . . . . 39
Information Buttons . . . . . . . . . . . . . . . . . . . . . . . . . . 39
PowerConnect Switch Management Buttons . . . . . . . . . . . . . . 39
Starting the Application . . . . . . . . . . . . . . . . . . . . . . . . . . 40

Contents 5
Resetting the Device . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41
Displaying Configuration on Demand . . . . . . . . . . . . . . . . . . . . 42
6 Configuring System Information
Defining Switch Information . . . . . . . . . . . . . . . . . . . . . . . . 43
Viewing the Switch Status . . . . . . . . . . . . . . . . . . . . . . . 43
Viewing System IP Address . . . . . . . . . . . . . . . . . . . . . . 44
Defining Interface Configuration . . . . . . . . . . . . . . . . . . . . 47
Viewing Jumbo Frames . . . . . . . . . . . . . . . . . . . . . . . . 49
Creating VLAN Membership . . . . . . . . . . . . . . . . . . . . . . 50
Defining VLAN Interface Settings . . . . . . . . . . . . . . . . . . . 51
Configuring LAG Membership . . . . . . . . . . . . . . . . . . . . . 52
Managing System Files . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Downloading Files From Server . . . . . . . . . . . . . . . . . . . . 55
Downloading Files From Server . . . . . . . . . . . . . . . . . . . . 55
Local User Database . . . . . . . . . . . . . . . . . . . . . . . . . 60
Integrated Cable Test for Copper Cables . . . . . . . . . . . . . . . . 61
Optical Transceivers Diagnostics . . . . . . . . . . . . . . . . . . . 63
Port Mirroring. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 64
Enabling Storm Control . . . . . . . . . . . . . . . . . . . . . . . . 65
7 Configuring Quality of Service
Quality of Service (QoS) Overview . . . . . . . . . . . . . . . . . . . . . 69
CoS Services . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 70
Defining CoS Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . 71
Configuring QoS Settings . . . . . . . . . . . . . . . . . . . . . . . 71
Mapping CoS Values to Queues . . . . . . . . . . . . . . . . . . . . 72
Mapping DSCP Values to Queues . . . . . . . . . . . . . . . . . . . 73
8 Viewing Statistics
RMON Statistics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75

6Contents

7
1
Introduction
This User’s Guide contains the information needed for installing, configuring and maintaining the
PowerConnect 2708, PowerConnect 2716, PowerConnect 2724, and PowerConnect 2748 Web-
managed Gigabit Ethernet switches.
These switches can be used to connect workstations and other network devices, such as:
•Servers
• Hubs (Wireless LAN Access Points)
•Routers
The PowerConnect devices are primarily for the Small Office/Home Office (SOHO) that require
high performance edge connectivity. These PowerConnect devices are ideal for the small to
medium business that requires high performance network connectivity along with advanced web
management features.The PowerConnect management features are designed to minimize
administrative management effort, while enhancing and improving network traffic control.
System Description
This section describes the hardware configurations of the PowerConnect 2708, PowerConnect
2716, PowerConnect 2724, and PowerConnect 2748. The switches are managed by Dell’s
OpenManage Switch Administrator.
8 1-Gigabit Ethernet Ports
The following figure illustrates the PowerConnect 2708 front panel.
Figure 1-1. PowerConnect 2708 Front Panel
The PowerConnect 2708 switch supports 8 GbE copper ports.
1

8
16 1-Gigabit Ethernet Ports
The following figure illustrates the PowerConnect 2716 front panel.
Figure 1-2. PowerConnect 2716 Front Panel
The PowerConnect 2716 switch supports 16 GbE copper ports.
24 1-Gigabit Ethernet Ports + 2 SFP Combo ports
The following figure illustrates the PowerConnect 2724 front panel.
Figure 1-3. PowerConnect 2724 Front Panel
The PowerConnect 2724 switch supports 24 GbE copper ports and has two SFP combo ports
(1000BASE-SX or 1000BASE-LX).
48 1-Gigabit Ethernet Ports
The following figure illustrates the PowerConnect 2748 front panel.
Figure 1-4. PowerConnect 2748 Front Panel

9
Features
General Features
Head of Line Blocking Prevention
Head of Line (HOL) blocking results in traffic delays and frame loss caused by traffic competing
for the same egress port resources. HOL blocking queues packets, and the packets at the head of
the queue are forwarded before packets at the end of the queue. By default, the device is configured
so that the HOL blocking prevention mechanism is active at all times, except when QoS (Quality
of Service), Flow Control or Back Pressure is active on a port where the HOL blocking prevention
mechanism is disabled on the whole system.
Management Modes
• Unmanaged Mode — Operates independent of user-configuration. The switch does not have
an IP address, nor is there a web management interface and thus cannot be managed. This is
the system default. From Unmanaged Mode, when the Managed Mode button is pressed, the
switch enters Managed Mode with the default IP address of 192.168.2.1.
•
Managed Mode — Provides switch management through a web interface, and maintains the
device configuration through power cycles. From Managed Mode, when the Managed Mode
button is pressed, the switch enters Unmanaged Mode.
•
Secure Mode (PowerConnect 2748 only) — Secure Mode works by the user configuring
the switch in Managed Mode
and then enabling Secure Mode. Once enabled, it prevents
users from making any further configuration changes to the switch. This is done by removing
the IP address to the switch so that it becomes inaccessible. In Secure Mode the switch
retains configuration through power cycles just like Managed Mode. To use Secure Mode, the
user puts the switch in Managed Mode, configures the switch as desired, and then switches to
Secure Mode via the web interface. To exit Secure Mode, the user presses the Managed Mode
button. From Secure Mode when the Managed Mode button is pressed, the switch enters
Managed Mode default configuration with the default IP address of 192.168.2.1.
Back Pressure Support
On half-duplex links, the receiving port prevents buffer overflows by occupying the link so that it is
unavailable for additional incoming traffic. The user may enable or disable this feature on a
per-port basis. The default status on all ports is set to
OFF . However, this applies to links operating
at Half Duplex only.

10
Auto Negotiation
Auto negotiation allows an Ethernet switch to advertise modes of operation. The auto negotiation
function provides the means to exchange information between two Ethernet switches that share a
point-to-point link segment, and to automatically configure both Ethernet switches to take
maximum advantage of their transmission capabilities. Port advertisement allows the system
administrator to configure the port speeds advertised.
Jumbo Frames Support
Jumbo frames are frames with an MTU (Maximum Transmission Unit) size of up to 10K bytes.
The Jumbo Frames Support feature, utilizes the network optimally by transporting the same data
using less frames.
The main benefits of this facility are reduced transmission overhead and reduced host processing
overhead. Jumbo frames are used for server-to-server transfers.
AutoMDI/MDIX Support
The switch automatically detects whether the cable connected to an RJ-45 port is crossed or
straight through.
Standard wiring for end stations is Media-Dependent Interface (MDI) and the
s tandard wiring for
hubs and switches is known as Media-Dependent Interface with Crossover (MDIX).
Auto MDI/MDIX works on 10/100/1000BASE-T Ethernet ports. This feature is automatically
enabled for the entire system and cannot be turned off by the user.
Flow Control Support (IEEE802.3X)
On Full Duplex links (FDX), the flow control mechanism allows the receiving side to signal to the
sending side that transmission must be halted temporarily, in order to prevent buffer overflows.
Virtual Cable Testing (VCT)
VCT technology provides the mechanism to detect and report potential cabling issues, such as
cable opens and cable shorts on copper links.
Cable analysis is available on Copper Cables (10BASE-T/100BASE-T/1000BASE-T), and is only
done when the link is down. When the system initiates a cable-testing operation, upon explicit user
action, the following parameters are detected:
• Cable Type and Status
•CableLength
• Fault-Distance

11
MAC Address Supported Features
MAC Address Capacity Support
The PowerConnect 2708, 2716, and 2724 switches support a total of 8K MAC addresses , and the
PowerConnect 2748 supports a total of 16K MAC addresses.
Auto-Learning MAC Addresses
The switch enables MAC address auto-learning from incoming packets. The MAC addresses are
stored in the Bridging Table.
Automatic Aging for MAC Addresses
MAC addresses from which no traffic is received for a given period of time are aged out. This
prevents the Bridging Table from overflowing.
Managed and Secure Modes VLAN-aware MAC-based Switching
In Managed or Secure mode, the switch system always performs VLAN-aware bridging. Classic
bridging (IEEE802.1D) is not performed (where frames are forwarded based only on their
destination MAC address). However, a similar functionality may be configured for untagged
frames. Addresses are associated with ports by learning them from the incoming frames source
address.
Unmanaged Mode Classic Bridging
In Unmanaged Mode, the switch performs classic bridging. Frames are forwarded based on their
destination MAC address only
, regardless of the VLAN tag.
Layer 2 Features
Port Mirroring
The port mirroring mechanism monitors and mirrors network traffic by forwarding copies of
incoming and outgoing packets from a monitored port to a monitoring port. Users can specify
which target port receives copies of all traffic passing through one or more source ports.
Storm Control
Storm Control enables limiting the amount of Multicast and Broadcast frames accepted and
forwarded by the switch. When Layer 2 frames are forwarded, Broadcast and Multicast frames are
flooded to all ports on the relevant VLAN. All nodes connected to these ports accept and attempt
to process these frames, thus placing load on both the network links and the host operating system.

12
VLAN Supported Features
VLAN Support
VLANs are collections of switching ports that comprise a single broadcast domain. Packets are
classified as belonging to a VLAN based on either the VLAN tag or based on a combination of the
ingress port and package contents. Packets sharing common attributes can be grouped in the same
VLAN.
Port Based Virtual LANs (VLANs)
Port-based VLANs classify incoming packets to VLANs based on their ingress port.
Link Aggregation
The PowerConnect 2708/2716/2724 /2748 switches support up to six aggregated links. Each of the
six aggregated links may be defined with up to four member ports to form a single Link Aggregated
Group (LAG).
The benefits of this facility are:
• Fault tolerance protection from physical link disruption
• Higher bandwidth connections
• Improved bandwidth granularity
• High bandwidth server connectivity
A LAG is composed of ports with the same speed set to full-duplex operation.
BootP and DHCP Clients
DHCP (Dynamic Host Configuration Protocol) enables additional setup parameters to be received
from a network server upon system startup. DHCP service is an on-going process. DHCP is an
extension to BootP.
The BootP client is operational if there is a corrupted or invalid software image. The BootP client
then continuously attempts to find a BootP server, by sending BootP requests to all ports on the
default VLAN, until a BootP server replies. The information replied is then used to provide the
switch system with a TFTP server IP address and a download file name. The switch can then
configure these values to the TFTP client and try to download a valid runtime image.
Class of Service (CoS) Features
The PowerConnect 2708/2716/2724 /2748 system enables users to define various services for traffic
classes of service. The underlying mechanism for supporting bandwidth management and control
is based on the use of multiple priority queues for classifying traffic. The switches support four
queues per port.

13
A CoS is defined by the user, whereby packets are related to the same Class of Service. After a
packet has been classified, it is assigned to one of the queues. The PowerConnect
2708/2716/2724
/2748 system can classify according to IPv4 information (DSCP).
Class Of Service 802.1p Support
The IEEE 802.1p signaling technique is an OSI Layer 2 standard for marking and prioritizing
network traffic at the data link/MAC sub-layer. 802.1p traffic is classified and sent to the
destination. No bandwidth reservations or limits are established or enforced. The 802.1p is a spin-
off of the 802.1Q (VLANs) standard.
Ethernet Switch Management Features
Web-Based Management
With a Web-based management interface, the Ethernet Switches’ system can be managed from
any Web browser. The system contains an Embedded Web Server (EWS), which serves HTML
pages, through which the system can be monitored and configured.
TFTP Trivial File Transfer Protocol
The PowerConnect 2708/2716/2724 /2748 switches support software boot image and software
download through TFTP.
Remote Monitoring
Remote Monitoring (RMON) is an extension to the Simple Network Management Protocol
(SNMP), which provides network traffic
statistics. RMON defines current and historical MAC-
layer statistics and control objects, allowing real-time information to be captured across the entire
network. The switches support one RMON group for Ethernet statistics. The system provides a
means to collect the statistics defined in RMON and to view the results, using the Web
management interface in the system.
Port Default Settings
The PowerConnect 2708/2716/2724 /2748 devices’s port default settings are as follows:
Function Default Setting
Flow Control (user-configurable) Off (disabled on ingress)
Backpressure (user-configurable) Off (disabled on ingress)
Auto Negotiation Speed (user-configurable) Enabled (1000 Mbps)
Auto Negotiation Duplex (user-configurable) Enabled (Full Duplex)
MDIX (not user-configurable) On (relevant to copper ports only)

14

15
2
Hardware Description
Switch Port Configurations
PowerConnect 2708/2716/2724/2748 Front Panel Port Description
The Dell™ PowerConnect™ 2708, 2716, 2724 and 2748 switches use 10/100/1000BASE-T ports on
the front panel for connecting to a network.
The Gigabit Ethernet ports can operate at 10, 100 or 1000 Mbps. These ports support auto-
negotiation, duplex mode (Half or Full duplex), and flow control. The combo 1000 Mbps optical
ports can only operate at 1000 Mbps, full-duplex mode.
The following figures illustrate the front panels and back panels of the PowerConnect
2708/2716/2724/2748 switches.
Figure 2-1. PowrConnect 2708 Front Panel
On the front panel there are eight ports which are numbered 1 to 8, top down and left to right. On
each port there are LEDs (Light Emitting Diode) to indicate the port status.
On the left side of the front panel is the Managed Mode LED which indicates the Ethernet switch
operational status. The Power LED on the front panel indicates whether the device is powered on
or not. A Managed Mode push-button, located on the right side on the front panel, restores the
device’s default settings configuration.

16
Figure 2-2. PowerConnect 2708 Back Panel
Figure 2-3. PowerConnect 2716 Front Panel
On the front panel, there are 16 ports, which are numbered 1 to 16, top down and left to right. On
each port there are LEDs to indicate the port status.
On the left side of the front panel is the Managed Mode LED which indicates the Ethernet switch
operational status. The Power LED on the front panel indicates whether the device is powered on
or not. A Managed Mode push-button, located on the right side on the front panel, restores the
device’s default settings configuration.
Figure 2-4. PowerConnect 2716 Back Panel

17
Figure 2-5. PowerConnect 2724 Front Panel
On the front panel there are 24 ports which are numbered 1 to 24, top down and left to right. On
each port there are LEDs to indicate the port status. There are two SFP (Small Form-Factor
Plugable) ports, designated as ports 23 and 24, for fiber connection. The two combo ports are
logical ports with two physical connections:
• An RJ-45 connection for Twisted Pair (TP) copper cabling
• An SFP port for swappable optical transceiver, which offers high-speed 1000BASE-SX or
1000BASE-LX connection.
NOTE: Only one of the two physical connections of a combo port can be used at any one time. Port
features and port controls are determined by the physical connection used. The system automatically
detects the media used on a combo port, and utilizes the information in all the control interfaces.
NOTE: The system can switch from the RJ-45 to the SFP (or vice versa) without resetting the device. If
both RJ-45 and SFP ports are present, the SFP port will be the active port, whereas the RJ-45 port will be
disabled.
On the left side of the front panel is the Managed Mode LED which indicates the Ethernet switch
operational status. The Power LED on the front panel indicates whether the device is powered on
or not. A Managed Mode push-button, located on the far right side on the front panel, restores the
device’s default settings configuration.
Figure 2-6. PowerConnect 2724 Back Panel

18
Figure 2-7. PowerConnect 2748 Front Panel
On the front panel, there are 48 ports, which are numbered 1 to 48, top down and left to right.
On each port, there are LEDs to indicate the port status. There are four SFP (Small Form-
Factor Plugable) ports, designated as ports 45, 46, 47 and 48, for fiber connection. The four
combo ports are logical ports with two physical connections:
• An RJ-45 connection for Twisted Pair (TP) copper cabling.
• An SFP port for swappable optical transceiver, which offers high-speed 1000BASE-SX or
1000BASE-LX connection.
NOTE: Only one of the two physical connections of a combo port can be used at any one time. Port
features and port controls are determined by the physical connection used. The system automatically
detects the media used on a combo port, and utilizes the information in all the control interfaces.
NOTE: The system can switch from the RJ-45 to the SFP (or vice versa) without resetting the device. If
both RJ-45 and SFP ports are present, the SFP port will be the active port, whereas the RJ-45 port will be
disabled.
On the top right side of the front panel is the Managed Mode LED, which indicates the
Ethernet switch operational status. The Fan LED indicates the device fan operations status and
the Power LED on the front panel indicates whether the device is powered on or not. A
Managed Mode push-button, located on the far right side on the front panel, sets the device
management mode.
The back panel contains an AC Power Supply Interface.
The following figure illustrates the back panel of the PowerConnect 2748 device.
Figure 2-8. PowerConnect 2748 Back Panel

19
Physical Dimensions
The PowerConnect 2708 switch has the following physical dimensions:
• Height — 43.2 mm (1.7008 in.)
• Width — 256 mm (10.079 in.)
• Depth — 161.7 mm (6.366 in.)
The PowerConnect 2716 and PowerConnect 2724 switches have the following physical dimensions:
• Height — 43.2 mm (1.7008 in.)
• Width — 330 mm (12.992 in.)
• Depth — 230.50 mm (9.075 in.)
The PowerConnect 2748 switch has the following physical dimensions:
• Height — 43.2 mm (1.70 in.)
• Width — 440 mm (17.32 in)
• Depth — 255 mm (10.04 in.)
LED Definitions
The front panel contains LEDs that indicate the status of links, power supply, fan status, and
Managed Mode status.
Power LED
On the PowerConnect 2708/2716/2724 /2748 front panel there is a Power LED. The following table
describes the Power Supply status LED indications.
Managed Mode LED
On the PowerConnect 2708/2716/2724/2748 front panel there is a Managed Mode LED
monitoring the switch node as well as indicating diagnostic test results. The following table
describes the Managed Mode LED indications.
Table 2-1. Power LED Indications
LED Color Description
Green Solid The switch is turned on.
Off The switch is not turned on.

20
Fan LED (2748 only)
On the PowerConnect 2748 front panel there is a fan LED. The following table describes the
fan status LED indications.
Port LEDs
10/100/1000BASE-T Port LEDs
Each 10/100/1000BASE-T port has two LEDs. Speed/Link/Activity is indicated on the left LED and
the duplex mode is indicated on the right LED.
The following figure illustrates the RJ-45 10/100/1000BASE-T LEDs.
Figure 2-9. RJ-45 Copper-based 10/100/1000BASE-T LEDs
The RJ-45 LED indications are described in the following table:
Table 2-2. Managed Mode LED Indications
LED Color Description
Green Flashing Indicates diagnostics in progress, firmware loading, or Managed Mode
transition.
Green Solid Indicates the switch is in Managed Mode.
Amber Solid Diagnostics has failed.
Amber Flashing No valid image.
Off Indicates Unmanaged mode or Secure mode (2748 only).
Table 2-3. Fan LED Indications
LED Color Description
Green Solid All fans are operating correctly.
Red Solid One or more fans have failed.