So often it seems that decisions in network engineering include the insidious little word or, such as security or performance, stability or flexibility, and reliability or cost.
While this or that choices may be helpful for preschool children (the red shirt or the blue one), for network engineers, framing options in this way limits the possibilities of their designs and deployments.
For engineers AND is a much more powerful word. I want security and performance, stability and flexibility, as well as availability and cost effectiveness.
Juniper Networks Virtual Chassis technology ends the “this or that” choices in switching and brings the new perspective of “this and that.” Virtual Chassis technology gives you all the reliability and feature functionality of a chassis and all the cost effective and pay-as-you-grow benefits of a fixed platform switch.
Juniper Networks EX 4200 Ethernet delivers Virtual Chassis (VC) technology to interconnect up to ten switch members that then operate as a single logical switch for simplified management and low latency. The flexibility to distribute the VC across wiring closets, data center racks and rows, or even across buildings in a campus delivers the high availability characteristics of a modular chassis without the limitations of the modular chassis’ sheet metal casing. The result is support for millisecond failover and re-route and substantial cost savings in procurement and sparing as well as efficiencies in space, power and cooling.
From a control plane perspective, each VC elects a member as the “master” switch which has full control over the entire VC. Consistent with other JUNOS-based modular platforms, the master serves as the active Routing Engine (RE0) for the VC – it runs the chassis management processes, network control protocols, calculates, maintains and distributes the forwarding table to other VC members, receives and transmits routing information, and stores the active configuration file for the VC.
The election of a dedicated “backup” member switch is what fundamentally differentiates the Juniper Virtual Chassis architecture over common stackable devices and provides a level of availability usually reserved for a modular chassis. The backup switch, which follows JUNOS-based modular platforms and serves as the backup routing engine (RE1), synchronizes with the master switch (RE0) and becomes the VC master in the event that the master switch fails. Failover to the backup is designed to minimize traffic loss, similar to a redundant control module within a modular chassis. The VC design leverages the same JUNOS chassis control code base so the VC has the ability to support JUNOS high-availability features such as graceful Routing Engine switchover (GRES), non-stop active routing (NSR) and unified in-service software upgrade (ISSU).
Other stackable devices lack a seamless failover to a backup, requiring the election of a new master in the event of a failure, resulting in network downtime and resultant loss of productivity.