Juniper Networks E-Series - Manual (Page 41)

Redundancy Features
E-Series Routers
1-19
For information about installing modules for line module redundancy, see
Chapter 5, Installing Modules . For information about configuring and
managing SRP module redundancy, see E-Series System Basics
Configuration Guide, Chapter 5, Managing Line Modules and SRP
Modules
.
Power
All E-series routers provide a power architecture that distributes
redundant –48 VDC feeds through the router to each line module, SRP
module, and fan module where DC-to-DC converters provide local
conversion to the required secondary voltages.
The ERX-310 router is available with either DC or AC power inputs. The
AC-powered version can be configured with one or two hot-swappable
power supplies for optional redundancy (see
Figure 1-8 and Figure 1-9 ).
The power supplies convert AC power to internal –48 V redundant DC
feeds that are then distributed through the router.
Fans
Forced air-cooling keeps the temperature of the E-series modules and
components within normal operating limits. In ERX-14xx models, six
cooling fans are located in a tray at the top of the router (see
Figure 1-4 ).
In ERX-7xx models, four cooling fans are located in a tray on one side of
the router (see
Figure 1-6 ). In the ERX-310 router, two cooling fans are
located in a tray on one side of the router (see Figure 1-8 ).
The system monitors the temperature of each module. If the temperature
of a module exceeds the maximum limit, the system immediately goes
into thermal protection mode. In this mode, the modules consume
extremely low levels of power. For information about troubleshooting
high operating temperatures, see
Chapter 10, Troubleshooting .
In ERX-7xx/14xx models, the fan tray has two redundant converters that
power the fans (for the ERX-14xx models, a –24 V, 50 W converter; for
the ERX-7xx models, a –12 V, 15 W converter). If one converter fails, the
other takes over. The ERX-310 router does not have redundant
converters.
For all E-series routers, the system software reports an alarm if any of the
fans or converters fail.