14 Cisco 550X Series Stackable Managed Switches Quick Start Guide
• For a combination port, the LEDs of the shared RJ-45 port light to 
respond to SFP+ port traffic.
OOB (if present)—If present, the Out of Band (OOB) port is a CPU's 
Ethernet port that can be used only as a management interface. Bridging 
between the OOB port and the in-band Layer 2 interface is not supported. 
Front Panel LEDs
RPS—(Green) Lights steady when the switch is ready and applicable for 
power backup through the Cisco Redundant Power System 2300 
(RPS2300), blinking when the power backing up is in process. If the LED 
flashes Amber, the Cisco RPS2300 is used for other switch. 
Fan—(Green) Lights steady when the cooling fan is operational. Flashes 
Amber when both two fans have failures. 
Master—(Green) Lights steady when the switch is a stack master.
System—(Green) Lights steady when the switch is powered on, and 
flashes when booting, performing self-tests, or acquiring an IP address. If 
the LED flashes Amber, the switch has detected a hardware failure, a 
firmware failure, and/or a configuration file error.
Stack ID—(Green) Lights steady when the switch is stacked and the 
corresponding number indicates its Stack ID. When a switch has a Stack ID 
greater than 4, a combination of the LEDs will light up to add up to the 
Stack ID. For example, Stack ID #5 is LED#1 and LED#4, Stack ID #8 will 
show LED#1, LED#3 and LED#4. 
LINK/ACT—(Green) Located on the left of each port. The light is steady 
when a link between the corresponding port and another device is 
detected. Flashes when the port is passing traffic. 
XG—(Green) Located on the right of a 10G port. Lights steady when 
another device is connected to the port, is powered on, and a 10 Gbps link 
is established between the devices. When the LED is off, the connection 
speed is under 10 Gbps or nothing is cabled to the port.
Gigabit—(Green) Located on the right of a Gigabit port or the OOB port. 
Lights steady when another device is connected to the port, is powered 
on, and a 1000 Mbps link is established between the devices. When the 
LED is off, the connection speed is under 1000 Mbps or nothing is cabled 
to the port.
SFP+ (if present)—(Green) Located on the right of a 10G port. Lights 
steady when a connection is made through the shared port. Flashes when 
the port is passing traffic.