Replacing an M120 CB

Removing an M120 CB

The router can have one or two CBs. They are located on either side of the FEBs in the rear of the chassis in the slots marked CB0 and CB1. With an RE installed, each CB weighs approximately 6.9 lb (3.1 kg).

Caution: Before you replace a CB, you must take the host subsystem offline. If there is only one host subsystem, taking the host subsystem offline shuts down the router. See Taking the M120 Host Subsystem Offline.

Caution: If the CB to be replaced is associated with the Routing Engine currently functioning as the master Routing engine, switch it to the backup before removing the CB. See Taking the M120 Host Subsystem Offline.

To remove a CB (see Figure 1):

1. Take the host subsystem offline. See Taking the M120 Host Subsystem Offline.
2. Place an electrostatic bag or antistatic mat on a flat, stable surface.
3. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist, and connect the strap to one of the ESD points on the chassis.
4. Loosen the captive screws on the ejector handles, using a Phillips (+) screwdriver, number 2.
5. Simultaneously rotate the ejector handles counterclockwise to unseat the CB.
6. Grasp the ejector handles and slide the CB about halfway out of the chassis.
7. Place one hand underneath the CB to support it and slide it completely out of the chassis.
8. Place the CB on the antistatic mat.
9. If you are not replacing the CB now, install a blank panel over the empty slot.

Figure 1: Removing an M120 CB

Installing an M120 CB

To install a CB (see Figure 2):

1. Attach an electrostatic discharge (ESD) grounding strap to your bare wrist and connect the strap to an approved site ESD grounding point. See the instructions for your site.
2. Carefully align the sides of the CB with the guides inside the chassis.
3. Slide the CB into the chassis, carefully ensuring that it is correctly aligned.
4. Grasp both ejector handles and rotate them simultaneously clockwise until the CB is fully seated.
5. Tighten the captive screws on the ejector handles, using a Phillips (+) screwdriver, number 2.
6. To verify that the CB is functioning normally, check the LEDs on its faceplate. The green OK LED should light steadily a few minutes after the CB is installed. If the FAIL LED is lit steadily, remove and install the CB again. If the FAIL LED still lights steadily, the CB is not functioning properly. Contact your customer support representative.

   To check the status of the CB, use the CLI command:

   
   

   user@host> show chassis environment cb

Figure 2: Installing an M120 CB