Juniper EX4200 Series Installation instructions

EX4200 Switch Hardware Guide
Published
2020-12-15

Juniper Networks, Inc.
1133 Innovation Way
Sunnyvale, California 94089
USA
408-745-2000
www.juniper.net
Juniper Networks, the Juniper Networks logo, Juniper, and Junos are registered trademarks of Juniper Networks, Inc. in
the United States and other countries. All other trademarks, service marks, registered marks, or registered service marks
are the property of their respective owners.
Juniper Networks assumes no responsibility for any inaccuracies in this document. Juniper Networks reserves the right
to change, modify, transfer, or otherwise revise this publication without notice.
EX4200 Switch Hardware Guide
Copyright © 2020 Juniper Networks, Inc. All rights reserved.
The information in this document is current as of the date on the title page.
YEAR 2000 NOTICE
Juniper Networks hardware and software products are Year 2000 compliant. Junos OS has no known time-related
limitations through the year 2038. However, the NTP application is known to have some difficulty in the year 2036.
END USER LICENSE AGREEMENT
The Juniper Networks product that is the subject of this technical documentation consists of (or is intended for use with)
Juniper Networks software. Use of such software is subject to the terms and conditions of the End User License Agreement
(“EULA”) posted at https://support.juniper.net/support/eula/. By downloading, installing or using such software, you
agree to the terms and conditions of that EULA.
ii

Table of Contents
About the Documentation | xi
Documentation and Release Notes | xi
Using the Examples in This Manual | xi
Merging a Full Example | xii
Merging a Snippet | xiii
Documentation Conventions | xiii
Documentation Feedback | xvi
Requesting Technical Support | xvi
Self-Help Online Tools and Resources | xvii
Creating a Service Request with JTAC | xvii
Overview
1
EX4200 System Overview | 19
EX4200 Switches Hardware Overview | 19
Benefits of the EX4200 Switch | 19
EX4200 Switches | 20
Uplink Modules | 21
Power over Ethernet Ports | 21
EX4200 Switch Models | 21
EX4200 Switch Hardware and CLI Terminology Mapping | 23
Chassis Physical Specifications for EX4200 Switches | 27
Field-Replaceable Units in EX4200 Switches | 28
EX4200 Chassis | 29
Front Panel of an EX4200 Switch | 29
Rear Panel of an EX4200 Switch | 30
LCD Panel in EX4200 Switches | 31
LCD Panel Modes | 32
Uplink Modules in EX4200 Switches | 33
SFP Uplink Module | 34
SFP+ Uplink Module and SFP+ MACsec Uplink Module | 35
iii

XFP Uplink Module | 37
Chassis Status LEDs in EX4200 Switches | 37
Management Port LEDs in EX4200 Switches | 39
Network Port LEDs in EX4200 Switches | 40
EX4200 Cooling System | 45
Fan Tray | 46
Airflow Direction in the EX4200 Switch Chassis | 46
EX4200 Power System | 47
Power Supply in EX4200 Switches | 47
AC Power Supplies | 48
DC Power Supplies | 49
PoE Power Budget and AC Power Supplies | 50
AC Power Supply LEDs in EX4200 Switches | 52
DC Power Supply LEDs in EX4200 Switches | 52
Power Specifications for EX4200 Switches | 53
AC Power Cord Specifications for EX4200 Switches | 54
Site Planning, Preparation, and Specifications
2
Site Preparation Checklist for EX4200 Switches | 58
EX4200 Site Guidelines and Requirements | 59
Environmental Requirements and Specifications for EX Series Switches | 60
General Site Guidelines | 65
Site Electrical Wiring Guidelines | 65
Rack Requirements | 66
Cabinet Requirements | 67
Requirements for Mounting an EX4200 Switch on a Desktop or Wall | 68
Clearance Requirements for Airflow and Hardware Maintenance for EX4200 Switches | 69
EX4200 Network Cable and Transceiver Planning | 70
Pluggable Transceivers Supported on EX4200 Switches | 71
SFP+ Direct Attach Copper Cables for EX Series Switches | 72
Cable Specifications | 72
List of DAC Cables Supported on EX Series Switches | 73
iv

Standards Supported by These Cables | 73
Understanding EX Series Switches Fiber-Optic Cable Signal Loss, Attenuation, and
Dispersion | 74
Signal Loss in Multimode and Single-Mode Fiber-Optic Cable | 74
Attenuation and Dispersion in Fiber-Optic Cable | 74
Calculating the Fiber-Optic Cable Power Budget for EX Series Devices | 75
Calculating the Fiber-Optic Cable Power Margin for EX Series Devices | 76
EX4200 Management Cable Specifications and Pinouts | 78
Management Cable Specifications | 78
Console Port Connector Pinout Information | 79
USB Port Specifications for an EX Series Switch | 79
RJ-45 Management Port Connector Pinout Information | 80
RJ-45 Port, SFP Port, SFP+ Port, QSFP+ Port, and QSFP28 Port Connector Pinout
Information | 81
RJ-45 to DB-9 Serial Port Adapter Pinout Information | 85
Uplink Modules Connector Pinout Information for EX4200 Switches | 86
Virtual Chassis Ports Connector Pinout Information for EX4200 Switches | 95
EX4200 Virtual Chassis | 99
Understanding EX4200, EX4500, and EX4550 Virtual Chassis Hardware Configurations | 99
Ports Used to Interconnect Virtual Chassis Members | 100
Number of Switches, Required Software Releases, and Member Roles That You Configure
in the Virtual Chassis | 101
Virtual Chassis Module | 102
Switch Role and Member ID on the LCD Panel | 102
Planning EX4200, EX4500, and EX4550 Virtual Chassis | 103
Virtual Chassis Cabling Configuration Examples for EX4200 Switches | 105
Initial Installation and Configuration
3
Unpacking and Mounting the EX4200 Switch | 110
Unpacking an EX4200 Switch | 110
Parts Inventory (Packing List) for an EX4200 Switch | 111
Register Products—Mandatory to Validate SLAs | 114
Installing and Connecting an EX4200 Switch | 114
Mounting an EX4200 Switch | 115
v

Mounting an EX4200 Switch on a Desk or Other Level Surface | 116
Mounting an EX4200 Switch on Two Posts in a Rack or Cabinet | 117
Mounting an EX4200 Switch on Four Posts in a Rack or Cabinet | 120
Mounting an EX4200 Switch in a Recessed Position in a Rack or Cabinet | 123
Mounting an EX4200 Switch on a Wall | 124
Connecting the EX4200 to Power | 126
Connect Earth Ground to an EX Series Switch | 127
Parts and Tools Required for Connecting an EX Series Switch to Earth Ground | 127
Special Instructions to Follow Before Connecting Earth Ground to an EX Series Switch | 132
Connecting Earth Ground to an EX Series Switch | 133
Connecting AC Power to an EX4200 Switch | 134
Connecting DC Power to an EX4200 Switch | 137
Connecting the EX4200 to External Devices | 141
Connect a Device to a Network for Out-of-Band Management | 141
Connect a Device to a Management Console Using an RJ-45 Connector | 142
Connecting the EX4200 to the Network | 143
Install a Transceiver | 143
Connect a Fiber-Optic Cable | 146
Configuring Junos OS on the EX4200 | 147
EX4200 Default Configuration | 148
Connecting and Configuring an EX Series Switch (CLI Procedure) | 153
Connecting and Configuring an EX Series Switch (J-Web Procedure) | 156
Configuring the LCD Panel on EX Series Switches (CLI Procedure) | 160
Disabling or Enabling Menus and Menu Options on the LCD Panel | 161
Configuring a Custom Display Message | 162
Dashboard for EX Series Switches | 163
Graphical Chassis Viewer | 164
System Information Panel | 166
Health Status Panel | 169
Capacity Utilization Panel | 173
Alarms Panel | 174
File System Usage | 174
vi

Chassis Viewer | 174
Maintaining Components
4
Maintaining the EX4200 Cooling System | 193
Removing a Fan Tray from an EX4200 Switch | 193
Installing a Fan Tray in an EX4200 Switch | 194
Maintaining the EX4200 Power System | 195
Removing a Power Supply from an EX4200 Switch | 195
Installing a Power Supply in an EX4200 Switch | 197
Maintain Transceivers | 199
Remove a Transceiver | 199
Remove a QSFP28 Transceiver | 202
Install a Transceiver | 204
Install a QSFP28 Transceiver | 206
Maintaining EX4200 Uplink Module | 208
Removing an Uplink Module from an EX4200 Switch | 208
Installing an Uplink Module in an EX4200 Switch | 211
Maintain Fiber-Optic Cables | 213
Connect a Fiber-Optic Cable | 214
Disconnect a Fiber-Optic Cable | 215
How to Handle Fiber-Optic Cables | 215
Replacing a Member Switch to Virtual Chassis | 216
Adding a New EX4200 Switch to an Existing EX4200 Virtual Chassis (CLI Procedure) | 217
Adding a New Switch to an Existing Virtual Chassis Within the Same Wiring Closet | 217
Adding a New Switch from a Different Wiring Closet to an Existing Virtual Chassis | 219
Adding a New Switch to an Existing Preprovisioned Virtual Chassis Using Autoprovisioning
and Automatic VCP Conversion | 221
Removing or Replacing a Member Switch of a Virtual Chassis Configuration | 223
Remove a Member Switch and Make Its Member ID Available for Reassignment to a
Different Switch | 224
Remove, Repair, and Reinstall the Same Switch | 225
Remove a Member Switch, Replace It with a Different Switch, and Reapply the Old
Configuration | 226
vii

Replace a Member Switch With a Different Type of Switch That Changes the Virtual
Chassis to Mixed Mode | 229
Maintaining Virtual Chassis Cable | 230
Disconnecting a Virtual Chassis Cable from an EX4200 Switch | 230
Connecting a Virtual Chassis Cable to an EX4200 Switch | 231
Troubleshooting Hardware
5
Troubleshooting EX4200 Components | 234
Understand Alarm Types and Severity Levels on EX Series Switches | 234
Chassis Component Alarm Conditions on EX4200 Switches | 236
Check Active Alarms with the J-Web Interface | 240
Monitor System Log Messages | 241
Troubleshooting Network Interfaces on EX4200 Switches | 246
The interface on the port in which an SFP or SFP+ transceiver is installed is down | 246
Troubleshooting Virtual Chassis Port Connectivity on an EX4200 Switch | 247
Virtual Chassis port (VCP) connection does not work | 247
Troubleshooting Power Supply Installation Alarms on EX4200 Switches | 248
The Switch Displays the “Unsupported PSU” Alarm | 248
Troubleshooting PoE Voltage Injection Failure in EX2300, EX3400, or EX4300 Switch Models
with PoE Capability | 249
Troubleshoot Temperature Alarms in EX Series Switches | 249
Contacting Customer Support and Returning the Chassis or Components
6
Returning an EX4200 Switch or Component for Repair or Replacement | 256
Returning an EX4200 Switch or Component for Repair or Replacement | 256
Locating the Serial Number on an EX4200 Switch or Component | 257
Listing the Switch and Components Details with the CLI | 257
Locating the Chassis Serial Number ID Label on an EX4200 Switch | 258
Locating the Serial Number ID Labels on FRUs in an EX4200 Switch | 258
Contact Customer Support to Obtain Return Material Authorization | 258
Packing an EX4200 Switch or Component for Shipping | 259
Packing an EX4200 Switch for Shipping | 260
Packing EX4200 Switch Components for Shipping | 261
viii

Safety and Compliance Information
7
General Safety Guidelines and Warnings | 264
Definitions of Safety Warning Levels | 265
Qualified Personnel Warning | 268
Warning Statement for Norway and Sweden | 269
Fire Safety Requirements | 269
Fire Suppression | 269
Fire Suppression Equipment | 269
Installation Instructions Warning | 271
Chassis and Component Lifting Guidelines | 271
Restricted Access Warning | 273
Ramp Warning | 275
Rack-Mounting and Cabinet-Mounting Warnings | 276
Grounded Equipment Warning | 282
Laser and LED Safety Guidelines and Warnings | 283
General Laser Safety Guidelines | 283
Class 1 Laser Product Warning | 284
Class 1 LED Product Warning | 285
Laser Beam Warning | 286
Radiation from Open Port Apertures Warning | 287
Maintenance and Operational Safety Guidelines and Warnings | 288
Battery Handling Warning | 289
Jewelry Removal Warning | 290
Lightning Activity Warning | 292
Operating Temperature Warning | 293
Product Disposal Warning | 295
General Electrical Safety Guidelines and Warnings | 296
Action to Take After an Electrical Accident | 297
ix

Prevention of Electrostatic Discharge Damage | 298
AC Power Electrical Safety Guidelines | 299
AC Power Disconnection Warning | 301
DC Power Electrical Safety Guidelines | 302
DC Power Disconnection Warning | 303
DC Power Grounding Requirements and Warning | 305
DC Power Wiring Sequence Warning | 307
DC Power Wiring Terminations Warning | 310
Multiple Power Supplies Disconnection Warning | 313
TN Power Warning | 314
Agency Approvals for EX Series Switches | 314
Compliance Statements for EMC Requirements for EX Series Switches | 315
Canada | 316
Taiwan | 317
European Community | 317
Israel | 317
Japan | 317
Korea | 318
United States | 318
FCC Part 15 Statement | 318
Nonregulatory Environmental Standards | 319
Compliance Statements for Acoustic Noise for EX Series Switches | 320
Statements of Volatility for Juniper Network Devices | 320
x

About the Documentation
IN THIS SECTION
Documentation and Release Notes | xi
Using the Examples in This Manual | xi
Documentation Conventions | xiii
Documentation Feedback | xvi
Requesting Technical Support | xvi
Use this guide to install hardware and perform initial software configuration, routine maintenance, and
troubleshooting for the EX4200 switch. After completing the installation and basic configuration procedures
covered in this guide, refer to the Junos OS documentation for information about further software
configuration.
Documentation and Release Notes
To obtain the most current version of all Juniper Networks®technical documentation, see the product
documentation page on the Juniper Networks website at https://www.juniper.net/documentation/.
If the information in the latest release notes differs from the information in the documentation, follow the
product Release Notes.
Juniper Networks Books publishes books by Juniper Networks engineers and subject matter experts.
These books go beyond the technical documentation to explore the nuances of network architecture,
deployment, and administration. The current list can be viewed at https://www.juniper.net/books.
Using the Examples in This Manual
If you want to use the examples in this manual, you can use the load merge or the load merge relative
command. These commands cause the software to merge the incoming configuration into the current
candidate configuration. The example does not become active until you commit the candidate configuration.
xi

If the example configuration contains the top level of the hierarchy (or multiple hierarchies), the example
isafull example. In this case, use the load merge command.
If the example configuration does not start at the top level of the hierarchy, the example is a snippet. In
this case, use the load merge relative command. These procedures are described in the following sections.
Merging a Full Example
To merge a full example, follow these steps:
1. From the HTML or PDF version of the manual, copy a configuration example into a text file, save the
file with a name, and copy the file to a directory on your routing platform.
For example, copy the following configuration to a file and name the file ex-script.conf. Copy the
ex-script.conf file to the /var/tmp directory on your routing platform.
system {
scripts {
commit {
file ex-script.xsl;
}
}
}
interfaces {
fxp0 {
disable;
unit 0 {
family inet {
address 10.0.0.1/24;
}
}
}
}
2. Merge the contents of the file into your routing platform configuration by issuing the load merge
configuration mode command:
[edit]
user@host# load merge /var/tmp/ex-script.conf
load complete
xii

Merging a Snippet
To merge a snippet, follow these steps:
1. From the HTML or PDF version of the manual, copy a configuration snippet into a text file, save the
file with a name, and copy the file to a directory on your routing platform.
For example, copy the following snippet to a file and name the file ex-script-snippet.conf. Copy the
ex-script-snippet.conf file to the /var/tmp directory on your routing platform.
commit {
file ex-script-snippet.xsl; }
2. Move to the hierarchy level that is relevant for this snippet by issuing the following configuration mode
command:
[edit]
user@host# edit system scripts
[edit system scripts]
3. Merge the contents of the file into your routing platform configuration by issuing the load merge
relative configuration mode command:
[edit system scripts]
user@host# load merge relative /var/tmp/ex-script-snippet.conf
load complete
For more information about the load command, see CLI Explorer.
Documentation Conventions
Table 1 on page xiv defines notice icons used in this guide.
xiii

Table 1: Notice Icons
DescriptionMeaningIcon
Indicates important features or instructions.Informational note
Indicates a situation that might result in loss of data or hardware
damage.
Caution
Alerts you to the risk of personal injury or death.Warning
Alerts you to the risk of personal injury from a laser.Laser warning
Indicates helpful information.Tip
Alerts you to a recommended use or implementation.Best practice
Table 2 on page xiv defines the text and syntax conventions used in this guide.
Table 2: Text and Syntax Conventions
ExamplesDescriptionConvention
To enter configuration mode, type
the configure command:
user@host> configure
Represents text that you type.Bold text like this
user@host> show chassis alarms
No alarms currently active
Represents output that appears on
the terminal screen.
Fixed-width text like this
•A policy term is a named structure
that defines match conditions and
actions.
•Junos OS CLI User Guide
•RFC 1997, BGP Communities
Attribute
•Introduces or emphasizes important
new terms.
•Identifies guide names.
•Identifies RFC and Internet draft
titles.
Italic text like this
xiv

Table 2: Text and Syntax Conventions (continued)
ExamplesDescriptionConvention
Configure the machine’s domain
name:
[edit]
root@# set system domain-name
domain-name
Represents variables (options for
which you substitute a value) in
commands or configuration
statements.
Italic text like this
•To configure a stub area, include
the stub statement at the [edit
protocols ospf area area-id]
hierarchy level.
•The console port is labeled
CONSOLE.
Represents names of configuration
statements, commands, files, and
directories; configuration hierarchy
levels; or labels on routing platform
components.
Text like this
stub <default-metric metric>;Encloses optional keywords or
variables.
< > (angle brackets)
broadcast | multicast
(string1 |string2 |string3)
Indicates a choice between the
mutually exclusive keywords or
variables on either side of the symbol.
The set of choices is often enclosed
in parentheses for clarity.
| (pipe symbol)
rsvp { # Required for dynamic MPLS
only
Indicates a comment specified on the
same line as the configuration
statement to which it applies.
# (pound sign)
community name members [
community-ids ]
Encloses a variable for which you can
substitute one or more values.
[ ] (square brackets)
[edit]
routing-options {
static {
route default {
nexthop address;
retain;
}
}
}
Identifies a level in the configuration
hierarchy.
Indention and braces ( { } )
Identifies a leaf statement at a
configuration hierarchy level.
; (semicolon)
GUI Conventions
xv

Table 2: Text and Syntax Conventions (continued)
ExamplesDescriptionConvention
•In the Logical Interfaces box, select
All Interfaces.
•To cancel the configuration, click
Cancel.
Represents graphical user interface
(GUI) items you click or select.
Bold text like this
In the configuration editor hierarchy,
select Protocols>Ospf.
Separates levels in a hierarchy of
menu selections.
>(bold right angle bracket)
Documentation Feedback
We encourage you to provide feedback so that we can improve our documentation. You can use either
of the following methods:
•Online feedback system—Click TechLibrary Feedback, on the lower right of any page on the Juniper
Networks TechLibrary site, and do one of the following:
•Click the thumbs-up icon if the information on the page was helpful to you.
•Click the thumbs-down icon if the information on the page was not helpful to you or if you have
suggestions for improvement, and use the pop-up form to provide feedback.
•E-mail—Send your comments to [email protected]. Include the document or topic name,
URL or page number, and software version (if applicable).
Requesting Technical Support
Technical product support is available through the Juniper Networks Technical Assistance Center (JTAC).
If you are a customer with an active Juniper Care or Partner Support Services support contract, or are
xvi

covered under warranty, and need post-sales technical support, you can access our tools and resources
online or open a case with JTAC.
•JTAC policies—For a complete understanding of our JTAC procedures and policies, review the JTAC User
Guide located at https://www.juniper.net/us/en/local/pdf/resource-guides/7100059-en.pdf.
•Product warranties—For product warranty information, visit https://www.juniper.net/support/warranty/.
•JTAC hours of operation—The JTAC centers have resources available 24 hours a day, 7 days a week,
365 days a year.
Self-Help Online Tools and Resources
For quick and easy problem resolution, Juniper Networks has designed an online self-service portal called
the Customer Support Center (CSC) that provides you with the following features:
•Find CSC offerings: https://www.juniper.net/customers/support/
•Search for known bugs: https://prsearch.juniper.net/
•Find product documentation: https://www.juniper.net/documentation/
•Find solutions and answer questions using our Knowledge Base: https://kb.juniper.net/
•Download the latest versions of software and review release notes:
https://www.juniper.net/customers/csc/software/
•Search technical bulletins for relevant hardware and software notifications:
https://kb.juniper.net/InfoCenter/
•Join and participate in the Juniper Networks Community Forum:
https://www.juniper.net/company/communities/
•Create a service request online: https://myjuniper.juniper.net
To verify service entitlement by product serial number, use our Serial Number Entitlement (SNE) Tool:
https://entitlementsearch.juniper.net/entitlementsearch/
Creating a Service Request with JTAC
You can create a service request with JTAC on the Web or by telephone.
•Visit https://myjuniper.juniper.net.
•Call 1-888-314-JTAC (1-888-314-5822 toll-free in the USA, Canada, and Mexico).
For international or direct-dial options in countries without toll-free numbers, see
https://support.juniper.net/support/requesting-support/.
xvii

1
CHAPTER
Overview
EX4200 System Overview | 19
EX4200 Chassis | 29
EX4200 Cooling System | 45
EX4200 Power System | 47

EX4200 System Overview
IN THIS SECTION
EX4200 Switches Hardware Overview | 19
EX4200 Switch Models | 21
EX4200 Switch Hardware and CLI Terminology Mapping | 23
Chassis Physical Specifications for EX4200 Switches | 27
Field-Replaceable Units in EX4200 Switches | 28
EX4200 Switches Hardware Overview
IN THIS SECTION
Benefits of the EX4200 Switch | 19
EX4200 Switches | 20
Uplink Modules | 21
Power over Ethernet Ports | 21
Juniper Networks EX Series Ethernet Switches provide scalable connectivity for the enterprise market,
including branch offices, campus locations, and data centers. The switches run the Juniper Networks Junos
operating system (Junos OS), which provides Layer 2 and Layer 3 switching, routing, and security services.
The same Junos OS code base that runs on EX Series switches also runs on all Juniper Networks M Series,
MX Series, and T Series routers and SRX Series devices.
Benefits of the EX4200 Switch
Compact solution—The EX4200 switch is a modular single rack unit device that is an apt solution for
crowded wiring closets and access switch locations such as data center, campus, and branch office
environments. It provides carrier-class reliability of modular systems with the economics and flexibility of
stackable platforms.
19

Support for Virtual Chassis—EX4200 switches support Virtual Chassis technology. You can interconnect
up to 10 EX4200 switches to form a Virtual Chassis and manage and operate them as a single network
entity.
EX4200 Switches
Juniper Networks EX4200 Ethernet Switches provide connectivity for medium- and high-density
environments and scalability for growing networks. These switches can be deployed wherever you need
high density of Gigabit Ethernet ports (24 to 480 ports) or redundancy. Typically, EX4200 switches are
used in large branch offices, campus wiring closets, and data centers where they can be positioned as the
top device in a rack to provide connectivity for all the devices in the rack.
You can connect individual EX4200 switches together to form one unit and manage the unit as a single
chassis, called a Virtual Chassis. You can add more member switches to the Virtual Chassis as needed, up
to a total of 10 members.
EX4200 switches are available in models with 24 or 48 ports with either all ports equipped for Power over
Ethernet (PoE/PoE+) or only 8 ports equipped for PoE. All models provide ports that have
10/100/1000Base-T Gigabit Ethernet connectors and optional 1-gigabit small form-factor pluggable (SFP)
transceivers, 10-gigabit small form-factor pluggable (SFP+) transceivers, or 10-gigabit small form-factor
pluggable (XFP) transceivers for use with fiber connections.
Additionally, a 24-port model provides 100Base-FX/1000Base-X SFP ports. This model is typically used
as a small distribution switch.
All EX4200 switches have dedicated 64-Gbps Virtual Chassis ports (VCPs) that enable you to connect the
switches to each other. You can also use optional uplink module ports to connect members of a Virtual
Chassis across multiple wiring closets.
To provide carrier-class reliability, EX4200 switches include:
•Dual redundant power supplies that are field-replaceable and hot-swappable. An optional additional
connection to an external power source is also available.
•A field-replaceable fan tray with three fans. The switch remains operational if a single fan fails.
•Redundant Routing Engines in a Virtual Chassis configuration. This redundancy enables graceful Routing
Engine switchover (GRES) and nonstop active routing (NSR).
•Junos OS with its modular design that enables failed system processes to gracefully restart.
EX4200 switches have these features:
•Run under Junos OS for EX Series switches
•Have options of 24-port and 48-port models
20