3

EX4200 Ethernet Switch

In a Virtual Chassis configuration, all switches are monitored and

managed as a single device, enabling enterprises to separate

physical topology from logical groupings of endpoints and allowing

more efficient resource utilization. Highly resilient topologies can

also be created using the GbE or 10GbE uplink ports to extend

the Virtual Chassis configuration across long distances spanning

multiple wiring closets, floors or even buildings.

East Closet

Floor N

10GbE

Single

Virtual

Chassis

System

EX4200

West Closet

EX4200

Figure 2: Using Virtual Chassis technology, up to 10 EX4200 switches

can be interconnected to create a single logical device spanning multiple wiring

closets, floors, or even buildings.

Features and Benefits

Chassis-Class Availability

The EX4200 line of Ethernet switches deliver the same HA

functionality and support many of the same failover capabilities

as other Juniper chassis-based systems.

Each EX4200 switch is capable of functioning as a

Route Engine. When two or more EX4200 switches are

interconnected, they share a single control plane among all

Virtual Chassis member switches. When two EX4200 switches

are interconnected, Junos OS automatically initiates an election

process to assign a master (active) and backup (hot-standby)

Route Engine. An integrated Layer 2 and Layer 3 Graceful Route

Engine Switchover (GRES) feature maintains uninterrupted

access to applications, services and IP communications in the

unlikely event of a primary RE failure.

Graceful Route

Engine Switchover

(GRES) for hitless

failovers

Master RE

Backup RE

EX4200

Figure 3: Support for Graceful Route Engine Switchover (GRES) ensures a smooth and

seamless transfer of control plane functions following a master Route Engine failure.

When more than two switches are interconnected in a Virtual

Chassis configuration, the remaining switch elements act as line

cards and are available to assume the backup RE position should

the designated master fail. Master, backup and line card priority

status can be assigned by the network operations team to

dictate the order of ascension; this N+1 RE redundancy, coupled

with the GRES, nonstop routing (NSR) and nonstop bridging

(NSB) capabilities of the Junos OS, assures a smooth transfer of

control plane functions following unexpected failures.

The EX4200 implements the same slot/module/port numbering

schema as other Juniper Networks chassis-based products

when numbering Virtual Chassis ports, providing true chassis-

like operations. By utilizing a consistent operating system and

a single configuration file, all switches in a Virtual Chassis

configuration are treated as a single device, simplifying overall

system maintenance and management.

Individually, the EX4200 offers a number of HA features that

are typically associated with modular chassis-based switches.

When combined with the field-proven Junos OS and L2/L3

failover capabilities, these features provide the EX4200 with

true carrier-class reliability.

• Redundant power supplies: The EX4200 line of Ethernet

switches support internal redundant, load-sharing, hot-

swappable and field-replaceable AC and DC power

supplies to maintain uninterrupted operations. Thanks to

their compact footprint, the EX4200 requires significantly

less power than chassis-based switches delivering

equivalent port densities.

• Hot-swappable fan tray with multiple blowers: The

EX4200 includes a hot-swappable, field-replaceable fan

tray with three blowers, providing sufficient cooling even if

one of the blowers were to fail.

• Redundant Trunk Group (RTG): To avoid the complexities

of the Spanning Tree Protocol (STP) without sacrificing

network resiliency, the EX4200 employs redundant trunk

groups to provide the necessary port redundancy and

simplify switch configuration.

• Cross-member link aggregation: Cross-member link

aggregation allows redundant link aggregation connections

between devices in a single Virtual Chassis configuration,

providing an additional level of reliability and availability.

• Carrier-class hardware: The EX4200 leverages a purpose-

built packet forwarding engine ASIC, the EX-PFE, which

integrates much of the same intellectual property used in

Juniper Networks carrier routers. As a result, the EX4200

delivers the same predictable, scalable functionality found

in the world’s largest networks.

• Non-Stop Bridging (NSB) and Non-Stop Routing (NSR):

NSB and NSR on the EX4200 ensure control plane

protocols, states and tables are synchronized between

Master and Standby REs to prevent protocol flaps or

convergence issues following a Routing Engine failover.