JUNOS High Availability

Virtual Chassis in the Switching Control Plane

The Juniper EX Series is the newest addition to the Juniper routing and switching portfolio. Lower-end models include the EX3200 and EX4200 series; the EX8200 series are larger switches. The EX3200 and EX4200 are stackable switches targeted as a solution for data centers, campuses, and branch office deployments. As we discussed in Chapter 2, each switch runs JUNOS software and has a routing engine (RE). With these low-end switches, you can create Virtual Chassis (VCs) of up to 10 switches to provide high availability of network resources. VC technology allows the RE on one of the switches in the group to manage all the other switches in the stack. The RE uses proven technologies, such as Graceful Routing Engine Switchover (GRES), Non-Stop Active Routing (NSR), and Non-Stop Bridging (NSB), to fully manage and operate the rest of the switches in the stack. These other line card switches have their own Packet Forwarding Engine (PFE) containing proprietary switching application-specific integrated circuits (ASICs).

Figure 5-1 illustrates a VC composed of stackable switches.

Figure 5-1. VC stack

As you can see in Figure 5-1, five switches are stacked together and joined by a VC backplane connection. This stack provides the equivalent throughput of a 128 Gbps high-speed backplane. The switches are connected using VC cables that can create a stack ...