MX204 Host Subsystem

Routing Engine Functions

The Routing Engine is built-in on the MX204 baseboard and cannot be replaced. The Routing Engine performs all route-processing functions, and provides performs chassis control and management plane functionality. The Routing Engine also provides control plane functions.

The Routing Engine supports the following functionalities to manage the operation of the router:

• System control functions such as environmental monitoring

• Routing Layer 2 and Layer 3 protocols

• Communication to components such as line cards, power supply, and cooling system

• Transparent clocking

• Alarm and logging functions

Routing Engine Components

The Routing Engine consists of the following internal components:

• High-performance 1.6-GHz Intel 8 Core X86 CPU

• 32-GB DDR4 RAM

• 100-GB SATA SSD

Routing Engine Front Panel

Figure 1 shows the front panel of the MX204 chassis.

Figure 1: MX204 Ports

1 — Rate-selectable ports	9 — RESET button
2 — Management (MGMT) port	10 — SSD0 LED
3 — BITS port with LEDs	11 — Alarm (ALM) LED
4 — USB port	12 — OK/FAIL LED
5 — 1PPS and 10MHz GPS input and output ports	13 — Time of day (ToD) port with LEDs (This port is reserved for future use)
6 — ONLINE LED	14 — Console (CON) port
7 — SSD1 LED	15 — 10-Gigabit Ethernet SFP+ ports
8 — OFFLINE button	16 — PTP grandmaster clock (GM/PTP) port

Routing Engine Interface Ports

The ports located on the router connect the Routing Engine to one or more external devices on which system administrators can issue Junos OS CLI commands to manage the router. In addition, ports to connect external clock interfaces for BITS and GPS function are also available on the router.

The Routing Engine interface ports with the indicated labels function are as follows (see Figure 1):

• CON—Connects the Routing Engine to a system console through a serial cable with an RJ-45 connector.

• MGMT—Connects the Routing Engine through an Ethernet connection to a management LAN (or any other device that plugs into an Ethernet connection) for out-of-band management. The port uses an autosensing RJ-45 connector to support 10-Mbps, 100-Mbps, or 1000-Mbps connections. Two small LEDs (an activity LED and a link LED) on the port indicate the connection in use.

  The link LED is:

  • lit amber (steady) when the 1000-Mbps link is up.

  • lit green (steady) when the 100-Mbps link is up.

  • Off when the 10-Mbps link is up.

  The activity LED is:

  • lit green (blinking) when traffic is passing through the port.

  • lit green (steady) when traffic is not passing through the port.

  Both activity and link LEDs are off when the link is down.

• BITS—Building-integrated timing supply (BITS) external clocking interface for connecting to external clocking devices.

• ToD—Time-of-day (TOD) port on the front panel of the router that enables you to connect external timing signal sources.

  Note:

  This port is reserved for future use.

• 10MHZ (one input and one output)—The 10-MHz timing connectors on the front panel of the router that connect to external clock signal sources. The clocking ports provide the synchronized output clocks from any one of the reference clock inputs based on the clock’s priority.

• PPS (one input and one output)—1-pulse-per-second (PPS) connectors on the front panel of the router that connect to external clock signal sources. The clocking ports provide the synchronized output clocks from any one of the reference clock inputs based on the clock’s priority.

• USB—Provides a removable media interface through which you can install Junos OS manually. Junos OS supports USB version 1.0 and later.