EX9251 Chassis
Chassis Physical Specifications of an EX9251 Switch
The EX9251 switch chassis is a rigid sheet-metal structure that houses all components of the switch. EX9251 is available in two variants—with AC power supply and with DC power supply. Table 1 summarizes the physical specifications of the EX9251 switch chassis.
Table 1: Physical Specifications of the EX9251 Switch Chassis
Description | Weight | Width | Depth | Height |
---|---|---|---|---|
Chassis | 22.7 lb (10.3 kg) | 19 in. (48.26 cm) |
| 1.72 in. (4.37 cm) |
Fan tray | 0.29 lb (0.13 kg) | 1.89 in. (4.8 cm) | 5.78 in. (14.68 cm) | 1.64 in. (4.17 cm) |
AC power supply | 2.2 lb (1 kg) | 2.23 in. (5.66 cm) | 14.5 in. (36.83 cm) | 1.58 in. (4.01 cm) |
DC power supply | 2.2 lb (1 kg) | 2.23 in. (5.66 cm) | 14.53 in. (36.91 cm) | 1.67 in. (4.24 cm) |
You can mount an EX9251 switch on four posts of a 19-in. rack or an ETSI rack.
Field-Replaceable Units in an EX9251 Switch
Field-replaceable units (FRUs) are components that you can replace at your site. The FRUs in EX9251 switches are hot-removable and hot-insertable. You can remove and replace them without powering off the switch. The FRUs in EX9251 switches are:
Power supplies
Fan trays
Transceivers
If you have a Juniper J-Care service contract, register any addition, change, or upgrade of hardware components at https://www.juniper.net/customers/support/tools/updateinstallbase/ . Failure to do so can result in significant delays if you need replacement parts. This note does not apply if you replace existing components with the same type of component.
To install an AC power supply in an EX9251 switch, follow instructions in Installing an AC Power Supply in an EX9251 Switch. To remove an AC power supply from an EX9251 switch, follow instructions in Removing an AC Power Supply from an EX9251 Switch.
To install a DC power supply in an EX9251 switch, follow instructions in Installing a DC Power Supply in an EX9251 Switch. To remove a DC power supply from an EX9251 switch, follow instructions in Removing a DC Power Supply from an EX9251 Switch.
To install a fan tray in an EX9251 switch, follow instructions in Installing a Fan Tray in an EX9251 Switch. To remove a fan tray from an EX9251 switch, follow instructions in Removing a Fan Tray from an EX9251 Switch.
To install a transceiver in an EX9251 switch, follow instructions in Install a Transceiver or Install a QSFP28 Transceiver. To remove a transceiver from an EX9251 switch, follow instructions in Remove a Transceiver or Remove a QSFP28 Transceiver.
LEDs on the Front Panel of an EX9251 Switch
The four rate-selectable ports on the front panel of an EX9251 switch has four LEDs each, which indicate the link status and activity on the port. Figure 1 shows the LEDs on the rate-selectable ports. Table 2 describes the link activity LED on those ports.

1 — LED0 | 3 — LED2 |
2 — LED1 | 4 — LED3 |
Table 2: Link/Activity LED on the Rate-Selectable Ports
LED | Color/State | Port Speed | ||
---|---|---|---|---|
100G | 40G | 10G | ||
LED 0 | Green | A 100G module is plugged in, the port link is up, and there is no alarm or failure. | A 40G module is plugged in, the port link is up, and there is no alarm or failure. | A 10G module is plugged in, the port link is up, and there is no alarm or failure. |
Red | The port link is down. | The port link is down. | The port link is down. | |
Amber | The interface is administratively disabled. | The interface is administratively disabled. | The interface is administratively disabled. | |
Off | No 100G module is plugged in. | No 40G module is plugged in. | No 10G module is plugged in. | |
LED 1 | Green | Not applicable | Not applicable | A 10G module is plugged in, the port link is up, and there is no alarm or failure. |
Red | Not applicable | Not applicable | The port link is down. | |
Amber | Not applicable | Not applicable | The interface is administratively disabled. | |
Off | Not applicable | Not applicable | No 10G module is plugged in. | |
LED 2 | Green | Not applicable | Not applicable | A 10G module is plugged in, the port link is up, and there is no alarm or failure. |
Red | Not applicable | Not applicable | The port link is down. | |
Amber | Not applicable | Not applicable | The interface is administratively disabled. | |
Off | Not applicable | Not applicable | No 10G module is plugged in. | |
LED 3 | Green | Not applicable | Not applicable | A 10G module is plugged in, the port link is up, and there is no alarm or failure. |
Red | Not applicable | Not applicable | The port link is down. | |
Amber | Not applicable | Not applicable | The interface is administratively disabled. | |
Off | Not applicable | Not applicable | No 10G module is plugged in. |
The eight 10-Gigabit Ethernet SFP+ ports on the front panel
of an EX9251 switch has one LED each, which indicate the link status
and activity on the port. Figure 2 shows the LEDs on the SFP+ ports labeled 1/0
, 1/2
, 1/4
, and 1/6
. Figure 2 shows the LEDs on the SFP+ ports labeled 1/1
, 1/3
, 1/5
, and 1/7
. Table 3 describes those LEDs.

1 — LED on the port labeled 1/0 | 3 — LED on the port labeled 1/4 |
2 — LED on the port labeled 1/2 | 4 — LED on the port labeled 1/6 |

1 — LED on the port labeled 1/1 | 3 — LED on the port labeled 1/5 |
2 — LED on the port labeled 1/3 | 4 — LED on the port labeled 1/7 |
Table 3: Link/Activity LED on the 10-Gigabit Ethernet SFP+ Ports
LED | Color/State | State and Description |
---|---|---|
Link activity | Green | The port link is up and there is no alarm or failure. |
Red | The port link is down. | |
Off | The port is not enabled. |
Figure 4 shows the LEDs on the management port and Figure 5 shows the LEDs on the BITS port. Table 4 describes the functions of the LEDs on the other ports on the front panel.

1 — Speed LED | 2 — Link/Activity LED |

1 — Activity LED | 2 — Link LED |
Table 4: Front Panel LEDs
LED | Color | State | Description |
---|---|---|---|
| Green | On steadily | Both Junos OS and Linux are successfully loaded on the switch. |
Blinking | The switch is starting Junos OS. | ||
Red | On steadily | The switch has loaded Linux. | |
Blinking | The switch is starting Linux. | ||
– | Off | The switch is offline. | |
| Green | On steadily | The switch is functioning normally. |
Red | Blinking | The switch has failed. | |
– | Off | The switch is not powered on. | |
| Red | On steadily | Critical alarm—Indicates a critical condition that can cause the switch to stop functioning. Possible causes include component removal, failure, or overheating, or any major software failure. |
Yellow | On steadily | Warning alarm—Indicates a serious but nonfatal error condition, such as a maintenance alert or a significant increase in component temperature. | |
– | Off | There is no alarm. | |
| Green | Blinking | SSD0 is being accessed by the switch. |
– | Off | SSD0 is not active or not being accessed. | |
| Green | Blinking | SSD1 is being accessed by the switch. |
– | Off | SSD1 is not active or not being accessed. | |
Link/Activity LED on the | Green | Blinking | The port and the link are active, and there is link activity. |
On steadily | The port and the link are active, but there is no link activity. | ||
Off | The port is not active. | ||
Speed LED on the | Green | On steadily | Link speed is 1000 Mbps. |
Amber | On steadily | Link speed is 100 Mbps. | |
– | Off | Link speed is 10 Mbps. | |
Activity LED on the | Green | On steadily | There is no loss (BITS is in locked state). |
– | Off | There is loss of signal or loss of line. | |
Link LED on the | Amber | On steadily | There is loss of signal or loss of line. |
– | Off | There is no loss (BITS is in locked state). |