Understanding the HCM
Purpose
Inspect the HCM to ensure that it works with its companion Routing Engine to provide control and monitoring functions for routing components. Also, inspect the HCM to ensure that it displays alarm status and takes the PIC online and offline.
What Is an HCM
The HCM on the M10i router performs the following functions:
- Monitoring and control of router components—The HCM collects statistics from all sensors in the system. When it detects a failure or alarm condition, it sends a signal to the Routing Engine, which generates control messages or sets an alarm. The HCM also relays control messages from the Routing Engine to the router components.
- Controlling component power-up and power-down—The HCM controls the power-up sequence of router components as they start and powers down components when their offline buttons are pressed.
- Signaling of mastership—In a router with more than one Routing Engine, the HCM signals to all router components which Routing Engine is the master and which is the standby.
- Alarm display—The HCM provides status and troubleshooting information at a glance. It is located on the front of the chassis below the FPC card cage, as shown in Figure 174. The LEDs on the HCM include two alarm LEDs. The circular red alarm LED at the upper right of the craft interface indicates a critical condition that can result in a system shutdown. The triangular yellow alarm below it indicates a less severe condition that requires monitoring or maintenance. Both alarms can occur simultaneously.
- PIC removal—If a PIC offline button is pressed, the HCM relays the request to the Compact Forwarding Engine Board (CFEB), which takes the PIC offline and informs the Routing Engine. Other PICs are unaffected, and system operation continues. For more information, see "PIC Offline Buttons" on page 21.
Figure 173 shows the M10i router HCM component.
The HCM has the following components:
- 100-Mbps Fast Ethernet switch—Carries signals and monitoring data between router components.
- Two LEDs—Indicate HCM status. The green LED is labeled
PWRand the blue LED labeledMSTR. See HCM LEDs for a description of the LED states. - Alarm LEDs—Display alarm conditions, if any exist.
- PIC offline buttons—Relay a request to the CFEB, which prepares a PIC for removal from the router, or brings the PIC online when it is replaced.
Two HCMs are installed into the midplane from the front of the chassis, as shown in Figure 174. The master HCM performs all functions and provides PIC removal buttons for the first FPC. The standby HCM provides PIC removal buttons for the second FPC. The HCM in the slot labeled HCM0 is paired with the Routing Engine in the slot labeled RE0. Likewise, the HCM in the slot labeled HCM1 is paired with the Routing Engine in the slot labeled RE1. By default, the HCM in the slot labeled HCM0 is the master.
