T4000 Component Redundancy; T4000 Chassis Description - Juniper T4000 Hardware Manual

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T4000 Component Redundancy

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T4000 Chassis Description

Copyright © 2013, Juniper Networks, Inc.
T4000 Router Description on page 3
T4000 Component Redundancy on page 15
The T4000 Core Router is designed so that no single point of failure can cause the entire
system to fail. The following major hardware components are redundant:
Switch Interface Boards (SIBs)—The router has five SIBs. For more information, see
"T4000 Switch Interface Board (SIB) Description" on page
Host subsystem—The host subsystem consists of a Routing Engine functioning together
with a control board. The router can have one or two host subsystems. If two host
subsystems are installed, one functions as the master and the other functions as the
backup. If the master host subsystem (or either of its components) fails, the backup
can take over as the master. To operate, each host subsystem requires a Routing Engine
installed in an adjacent slot to a control board. For more information, see
RE-C1800 Routing Engine Description" on page
"T4000 Host Subsystem Description" on page
If the Routing Engines are configured for nonstop active routing, the backup Routing
Engine automatically synchronizes its configuration and state with the master Routing
Engine. Any update to the master Routing Engine state is replicated on the backup
Routing Engine. If the backup Routing Engine assumes mastership, packet forwarding
continues through the router without interruption. For more information about nonstop
active routing, see the Junos OS High Availability Library for Routing Devices.
SONET Clock Generators (SCGs)—The router has a standard configuration of one
SCG. A second can be purchased to function as backup. If one SCG fails, the other
becomes the master SCG. Mastership of the SCGs is independent of the host subsystem,
so routing functions are not affected. For more information, see
Generators (SCGs) Description" on page
Power supplies—The router has two power supplies, which share the load evenly. If
one power supply fails, the other power supply can provide full power to the router
indefinitely. For more information, see
Cooling system—The cooling system has redundant components, which are controlled
by the host subsystem. If one of the fans fails, the host subsystem increases the speed
of the remaining fans to provide sufficient cooling for the router indefinitely. For more
information, see "T4000 Cooling System Description" on page
T4000 Router Description on page 3
The T4000 Core Router chassis is a rigid sheet metal structure that houses all the other
router components (see Figure 6 on page 17
Chapter 3: T4000 Hardware Components Overview
46.
40, "T4000 LCC-CB" on page
35.
"T4000 SONET Clock
49.
"T4000 Power System Description" on page
21.
and Figure 7 on page 18). The chassis
"T4000
37, and
43.
15