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MX104 Chassis

MX104 Chassis Overview

The MX104 router contains a front panel with slots in which you can install field-replaceable units (FRUs). From the front of the chassis, you can see the following components (see Figure 1):

  • Alarm console port labeled ALARM, which accepts a DE-15 alarm cable.

  • Alarm LEDs that indicate major or minor alarms.

  • Built-in 10-Gigabit Ethernet MIC with four ports that accept 10-Gigabit Ethernet SFP+ transceivers.

  • ONLINE/OFFLINE button.

  • Chassis status LED labeled SYS OK

  • External building integrated timing system (BITS) port labeled EXT REF CLOCK

  • Time-of-day (TOD) port

  • External clocking ports supporting 1-PPS and 10-MHz input and output

  • ESD point

  • Fan tray, which contains five fans and an air filter

  • Four slots for installing MICs


    For a detailed description of the MX104 port and interface numbering see MX104 Port and Interface Numbering.

  • Two slots for installing either AC or DC power supplies, labeled PS 0 and PS 1

  • Two slots for installing Routing Engines, labeled RE 0 and RE 1

Figure 1: Front View of the MX104 RouterFront View of the MX104 Router
Alarm input and output contacts
Grounding terminals
Alarm LEDs
Fan tray
10-Gigabit Ethernet SFP+ ports
MIC slots 0/1 and 1/1
Online/offline button
Routing Engine slot 1
System status LED
Routing Engine slot 0
External reference clocking port
Power supply slot 1
Time-of-day (ToD) port
Power supply slot 0
1-PPS and 10-MHz GPS input and output ports
MIC slots 0/0 and 1/0
ESD point

MX104 Hardware and CLI Terminology Mapping

The MX104 router supports the components in Table 1, listed in alphabetic order.

Table 1: MX104 Routers Hardware Components and CLI Terminology


Hardware Model Number

CLI Name





MX104 Universal Routing Platform Overview

Cooling system, including fan trays and air filters

MX104 Cooling System and Airflow Overview

Air filter kit



Fan tray


Fan Tray

Power system components

MX104 Power Overview

Power blank cover



Power supply

  • AC: PWR-MX104-AC

  • DC: PWR-MX104-DC



N/A (built-in)

4x 10GE(LAN) SFP+

MX104 Modular Interface Card (MIC) Overview

See MX Series Interface Module Reference.

MX104 Modular Interface Card (MIC) Overview


N/A (built-in)


MX104 Modular Interface Card (MIC) Overview

Routing Engine


Routing Engine

MX104 Routing Engine Overview


See MX Series Interface Module Reference.


MX104 Modular Interface Card (MIC) Overview

MX104 Component Redundancy

The MX104 chassis provides redundancy and resiliency. The hardware system is fully redundant, including power supplies, Routing Engines, and cooling system.

A fully configured router is designed so that no single point of failure can cause the entire system to fail. Only a fully configured router provides complete redundancy. All other configurations provide partial redundancy. The following major hardware components are redundant:

  • Power supplies—In a redundant configuration, the router contains either two AC or DC power supplies that install into the front of the chassis. The slots are labeled PS 0 and PS 1 (left to right). Each power supply provides power to all components in the router. When two power supplies are present, they share power almost equally within a fully populated system. If one power supply in a redundant configuration fails or is removed, the remaining power supplies assume the entire electrical load without interruption. Two power supplies provide the maximum configuration with full power for as long as the router is operational.

  • Routing Engine—If two Routing Engines are installed, one functions as the primary and the other functions as the backup. If the primary Routing Engine fails, the backup can take over as the primary.

  • Cooling system—The cooling system has redundant components, which are controlled by the host subsystem. If one of the fans fails, the host subsystem increases the speed of the remaining fans to provide sufficient cooling for the router indefinitely.

MX104 Alarm Contact Port Overview

The MX104 router has four external alarm contacts (also known as potential free contacts) for connecting the router to external alarm devices. The port labeled ALARM uses a 15-pin D-type connector. The external alarm contact has 15 pins that accept a single core wire from external alarm devices. A DE-15 alarm cable is required to connect the MX104 router to external alarm devices. Use the gauge wire appropriate for the external device that you are connecting.

Whenever a system condition triggers an alarm, the alarm relay contacts are activated, which in turn activates the external alarm devices. The alarm setting is open or closed.

You can connect and configure two output alarms and four input alarms. Two additional output alarms are reserved and are used to indicate major and minor system alarms. Each output and input alarm has two contacts for connecting the router to external alarm devices. Contact 1 of each alarm can be configured as Normally Open [NO] or Normally Closed [NC] through the CLI. Contact 2 of each alarm functions as a reference [REF] or negative potential terminal for Contact 1 of the corresponding alarm and provides a current path for external alarm devices. Table 2 describes the functions of the alarm contacts.

Table 2: Alarm Relay Contact Functions

Contact Name

Contact Name


Contact 1

Normally Open [NO]

Current is not flowing through Contact 1 and Contact 2 [REF] when operating normally. When the current flows, the closed alarm is generated.

Normally Closed [NC]

Current is flowing through Contact 1 and Contact 2 [REF] when operating normally. When the current stops flowing, the open alarm is generated.

Contact 2

Reference [REF]

Provides the current path for the external alarm-reporting device and functions as a reference or negative potential terminal for Contact 1.

Figure 2 shows an example of a wiring diagram for a simple output alarm-reporting device. In this case, the device is a light bulb that illuminates when the device encounters a condition that activates the red alarm LED and relay contacts. The alarm relay contacts can also be used to activate other devices such as bells or buzzers.

Figure 2: Sample Output Alarm-Reporting DeviceSample Output Alarm-Reporting Device

Figure 3 shows an example of a wiring diagram for a simple input alarm-reporting device. In this case, the push button switch is an alarm sensor that triggers an input alarm when a door-open condition occurs.

Figure 3: Sample Input Alarm-Reporting DeviceSample Input Alarm-Reporting Device

MX104 LEDs Overview

Alarm LEDs on the Front Panel

Two LEDs, located to the right of the alarm contact port indicates major and minor alarms for the router (see Figure 4).

Figure 4: Alarm LEDs on the MX104 RouterAlarm LEDs on the MX104 Router

Table 3 describes the alarm LED in more detail.

Table 3: Alarm LEDs on the Front Panel




LED Control Name



On steadily

Critical alarm

Indicates a critical condition that can cause the router to stop functioning. Possible causes include component removal, failure, or overheating.


On steadily

Warning alarm

Indicates a serious but nonfatal error condition, such as a maintenance alert or a significant increase in component temperature.

System LED on the Front Panel

One bicolor LED labeled SYS OK indicates the status of the router. Table 4 describes the system LED in more detail.

Table 4: System LED on the Front Panel








Router has no primary Routing Engine.

On steadily

Router is functioning normally.


On steadily

Router has reported a minor alarm.


On steadily

Router has failed.


Each hot-removable and hot-insertable MIC has LEDs located on the faceplate. For more information about LEDs on the MIC faceplate, see the “LEDs” section for each MIC in the MX Series Interface Module Reference.

For information about the built-in MIC LEDs, see MX104 Modular Interface Card (MIC) Overview.

Power Supply LED

One LED labeled PS STATUS indicates the status of the power supply. For more information, see MX104 Power Overview.

Routing Engine LEDs

Three LEDs indicate the status of the Routing Engine. For more information, see MX104 Routing Engine Overview.