Juniper Networks MX240 manual Midplane, Dense Port Concentrators DPCs

MX240 Ethernet Services Router Hardware Guide

Midplane

The midplane is located toward the rear of the chassis and forms the rear of the DPC card cage (see Figure 5 on page 8). The DPCs and SCBs install into the midplane from the front of the chassis, and the power supplies install into the midplane from the rear of the chassis. The cooling system components also connect to the midplane.

The midplane performs the following major functions:

■Data path—Data packets are transferred across the midplane between the DPCs through the fabric ASICs on the SCBs.

■Power distribution—The router power supplies connect to the midplane, which distributes power to all the router components.

■Signal path—The midplane provides the signal path to the DPCs, SCBs, Routing Engines, and other system components for monitoring and control of the system.

Figure 5: Midplane

Dense Port Concentrators (DPCs)

A Dense Port Concentrator (DPC) is optimized for Ethernet density and supports up to 40 Gigabit Ethernet or four 10-Gigabit Ethernet ports (see Figure 6 on page 9). The DPC assembly combines packet forwarding and Ethernet interfaces on a single board, with four 10-Gbps Packet Forwarding Engines. Each Packet Forwarding Engine consists of one I-chip for Layer 3 processing and one Layer 2 network processor. The DPCs interface with the power supplies and Switch Control Boards (SCBs).

The router has two dedicated DPC slots. DPCs install horizontally in the front of the router (see Figure 6 on page 9). One multifunction slot numbered 1/0 supports either one DPC or one SCB. The DPC slots are numbered 1/0, 1, and 2 bottom to top. A DPC can be installed in any slot on the router that supports DPCs.

You can install any combination of DPC types in the router.

DPCs are hot-removable and hot-insertable, as described in “Field-Replaceable Units (FRUs)” on page 87. When you install a DPC in an operating router, the Routing

8 ■ Midplane