Juniper JUNOS OS 10.3 - SOFTWARE Manual page 1090

Complete Software Guide for Junos
Requirements
Overview and Topology
994
®
OS for EX Series Ethernet Switches, Release 10.3
This example uses the following hardware and software components:
Junos OS Release 9.3 or later for EX Series switches
Six EX4200-24T switches
Four SFP uplink modules
Before you begin configuring fast failover, be sure you have:
Mounted the switches. See Mounting an EX3200 or EX4200 Switch on Two Posts in
1.
a Rack or Cabinet, Mounting an EX3200 or EX4200 Switch on a Desk or Other Level
Surface, or Mounting an EX3200 or EX4200 Switch on a Wall.
Cabled the switches in a multiple-ring topology to create the Virtual Chassis
2.
configuration. See Connecting a Virtual Chassis Cable to an EX4200 Switch and
"Example: Configuring a Virtual Chassis Interconnected Across Multiple Wiring Closets"
on page 963. See Figure 22 on page 995 for an illustration of a multiple-ring topology.
In a Virtual Chassis configuration, fast failover automatically reroutes traffic and reduces
traffic loss in the event of a link failure or a member switch failure. By default, fast failover
is enabled on all dedicated Virtual Chassis ports (VCPs). If you configure uplink module
ports as VCPs, you must manually configure fast failover on these ports.
For fast failover to be effective, the Virtual Chassis members must be configured in a ring
topology. The ring topology can be formed by using either dedicated Virtual Chassis ports
(VCPs) or user-configured uplink module VCPs. Fast failover is supported only in a ring
topology that uses identical port types, for example, either a topology that uses all
dedicated VCPs or one that uses all uplink module VCPs. Fast failover is not supported
in a ring topology that includes both dedicated VCPs and uplink module VCPs. Fast
failover is supported, however, in a Virtual Chassis configuration that consists of multiple
rings.
Figure 22 on page 995 shows an example of a multiple-ring topology.
Copyright © 2010, Juniper Networks, Inc.