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JNCIS-ENT · Junos OS 21.4R3

Master Junos
Enterprise Switching.

The only book that takes you from a green CLI prompt to JNCIS-ENT exam-ready — on a real EX4300 with Junos OS 21.4R3. 18 chapters, 7 hands-on labs, and a 60-question mock exam, every command verified against the official Juniper TechLibrary.

18 Chapters 7 Labs 60-Q Mock Exam Primary-source verified
₹1199
/ $11.99 USD

One-time purchase · instant access · lifetime updates

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Built by an engineer, not a course mill
CT
Junos · EX4300
Junos
Enterprise
Switching
Complete Engineer’s Guide
JNCIS-ENT Aligned · Junos 21.4R3
ByAbhijeet Kumar
cafetele · 2026
18
Chapters
5
Appendices
7
Hands-on Labs
12
Colour Diagrams
60
Mock-Exam Qs
// what's inside

Everything you need for the JNCIS-ENT, none of the fluff.

Each chapter is built around a working EX4300 with Junos OS 21.4R3. Every CLI block is copy-pasted from a real device and cross-checked against Juniper's TechLibrary. No vendor marketing, no AI-paraphrased filler — just the things you actually configure on the wire.

L2 Foundations

Ethernet bridging, MAC learning & aging, broadcast/unicast forwarding, switch architecture on the EX4300.

VLANs & IRB

Access/trunk modes, native & voice VLANs, IRB interfaces, inter-VLAN routing, the whole bridge-domain model.

RSTP & MSTP

Convergence math, root selection, BPDU mechanics, edge ports, BPDU/loop/root protection, region planning.

LAGs & RTGs

Static & LACP aggregation, hashing, redundant trunk groups for non-LACP redundancy, storm control.

Port Security

MAC limits, persistent learning, MACsec, DHCP snooping, Dynamic ARP Inspection, IP Source Guard.

HA: GRES / NSR / NSB

Graceful Routing Engine Switchover, Non-Stop Routing, Non-Stop Bridging — how Junos keeps the data plane up.

Virtual Chassis

Mastership election, VCP rings, member numbering, line-card mode, ISSU planning — with full deployment walk-through.

Mist Wired Assurance

Cloud claim, template hierarchy, Marvis SLE-based troubleshooting, day-one deployment for greenfield campuses.

60-Question Mock Exam

Full simulated JNCIS-ENT switching paper with explanations, weighted to match the official objectives map.

// exam alignment

Built directly on the JNCIS-ENT blueprint.

No guesswork on what to study. Every chapter is mapped to one or more JNCIS-ENT switching objectives, and Appendix B gives you the reverse map — pick an objective, jump straight to the chapter section.

Objectives covered

The JNCIS-ENT switching half

Every Layer 2 objective on the official Juniper exam blueprint, demonstrated on a real EX4300.

  • VLANs & trunking (incl. native, voice)
  • Spanning Tree (STP, RSTP, MSTP) + protections
  • Aggregated Ethernet, LACP, RTGs
  • Storm control & L2 firewall filters
  • MAC limiting, persistent learning, MACsec
  • DHCP snooping, DAI, IP Source Guard
  • GRES, NSR, NSB
  • Virtual Chassis design & deployment
  • Mist Wired Assurance (modern Juniper campus)
Sources

Primary-source verified

Every quantitative claim, switch capability, and CLI verb checked against the live Juniper TechLibrary — not blog posts, not training slides, not AI memory.

  • Junos OS 21.4R3 documentation
  • EX4300 hardware datasheet (real fabric, queue, buffer numbers)
  • Juniper KB articles for known-issue contexts
  • Mist documentation portal for cloud workflow
  • IEEE 802.1Q / 802.1D / 802.1w / 802.1s where invoked
  • RFCs cross-referenced for protocol behaviour
  • Numbers we couldn't verify? We say "consult the live datasheet" — never made up.
// table of contents

18 chapters · 5 appendices.

Front matter and the first three chapters are free to preview. The rest unlocks instantly on purchase.

Part I

Bridging & Architecture

  • 01.Ethernet Bridging Foundations
  • 02.Junos Switching Architecture on the EX4300
Part II

VLANs & IRB

  • 03.VLAN Fundamentals on Junos
  • 04.Voice VLAN, Native VLAN, and IRB
Part III

Spanning Tree

  • 05.Spanning Tree Foundations
  • 06.Deploying Spanning Tree on Junos
  • 07.Spanning Tree Protection
  • 08.Multiple Spanning Tree Protocol
Part IV

Aggregation & Hardening

  • 09.LAGs and Redundant Trunk Groups
  • 10.Storm Control
  • 11.Layer 2 Firewall Filters
Part V

Port Security & HA

  • 12.Port Security I — MAC Limiting, Persistent Learning, MACsec
  • 13.Port Security II — DHCP Snooping, DAI, IP Source Guard
  • 14.High Availability — GRES, NSR, NSB
Part VI

Virtual Chassis & Mist

  • 15.Virtual Chassis Concepts
  • 16.Deploying Virtual Chassis
  • 17.Mist Wired Assurance — Overview
  • 18.Mist Wired Assurance — Day-One Deployment
Appendices

Reference material

  • A.Junos CLI Quick Reference
  • B.JNCIS-ENT Objectives Map
  • C.Lab Walk-Throughs
  • D.Glossary
  • E.60-Question Mock Exam & Answer Key
// hands-on labs

Seven labs you can actually rebuild.

Each lab gives you the topology, the configuration block, the expected operational output, and the rollback. Run them on real EX4300s, in EVE-NG, or on Juniper vSwitch images.

LAB 01

VLAN & Trunk Bring-up

Three switches, two VLANs, native + voice, full reachability.

LAB 02

RSTP Convergence

Force a topology change & measure convergence with traceoptions.

LAB 03

STP Protection

BPDU guard, root guard, loop protect — deliberately tripped & recovered.

LAB 04

LAG + RTG Failover

LACP active-active, plus a non-LACP RTG sub-second flip.

LAB 05

DHCP Snooping + DAI + IPSG

Rogue DHCP & ARP poisoning blocked end-to-end.

LAB 06

Virtual Chassis Build

4-member EX4300 ring, mastership rules, member renumber.

LAB 07

Mist Day-One Onboard

Claim a switch, push template hierarchy, read SLE in Marvis.

BONUS

Pre-test gauntlet

20-Q rapid-fire the day before your exam.

// sample from the book

Real CLI. Real output. Verified blocks only.

Here’s a snippet from Chapter 9 (LAGs & LACP), pulled directly from a working EX4300 with Junos OS 21.4R3:

ex4300-acc1 · root@ex4300-acc1 Junos 21.4R3
## Build a 2-port LACP bundle ae0 across ge-0/0/0 and ge-0/0/1
root@ex4300-acc1# set chassis aggregated-devices ethernet device-count 4
root@ex4300-acc1# set interfaces ge-0/0/0 ether-options 802.3ad ae0
root@ex4300-acc1# set interfaces ge-0/0/1 ether-options 802.3ad ae0
root@ex4300-acc1# set interfaces ae0 aggregated-ether-options lacp active periodic fast
root@ex4300-acc1# set interfaces ae0 unit 0 family ethernet-switching interface-mode trunk vlan members all
root@ex4300-acc1# commit

## Verify — both members should be in 'Distributing/Collecting'
root@ex4300-acc1> show lacp interfaces ae0
Aggregated interface: ae0
    LACP state: Role Exp Def Dis  Col  Syn  Aggr Timeout  Activity
      ge-0/0/0   Actor   No  No  Yes  Yes  Yes  Yes  Fast      Active
      ge-0/0/1   Actor   No  No  Yes  Yes  Yes  Yes  Fast      Active
// about the author

Written by an engineer who actually deploys these networks.

AK

Abhijeet Kumar

Telecom & Network Engineer · CafeTele Founder

Abhijeet has spent years deploying L2/L3 campus networks, 4G/5G transport, and RAN optimisation across multiple operators. He writes CafeTele books from his own lab and notes — not from a content-mill template. The "primary-source-only" rule on this book exists because the author refuses to ship a single specification number he hasn’t personally checked against vendor documentation. If you want a Junos book that respects your time and won’t embarrass you in front of a real operations team, this is it.

// faq

Frequently asked questions.

Is this book aligned to the JNCIS-ENT exam?

Yes. Every chapter is mapped to a JNCIS-ENT switching objective, Appendix B is the reverse map, and Appendix E is a 60-question simulated exam with full explanations weighted to match the official blueprint.

Which Junos version does this cover?

Junos OS 21.4R3 on the EX4300 platform — the long-term-supported release widely deployed in production today. Mist content reflects the current cloud workflow.

What's free and what's paid?

The Preface, How-to-Use, About-the-Exam, full Table of Contents, and Chapters 1–3 (Ethernet Bridging, Junos Switching Architecture, VLAN Fundamentals) are free in the in-browser reader. Chapters 4–18 + all five appendices unlock immediately on purchase.

How is delivery? Do I get a PDF?

Reading happens in a fast, mobile-friendly in-browser reader at /junos-switching-book/reader.html. There’s no PDF download — this lets us push corrections and exam-blueprint updates instantly. Your access is tied to your CafeTele account.

How long do I have access?

120 days of access from purchase, including all updates published in that window. Lifetime updates: anything you’ve already unlocked stays unlocked, and major content additions to the same edition are pushed automatically.

Can I pay in INR? In USD?

Both. The site auto-detects your region and shows the right currency. Razorpay handles UPI, cards, net banking for India, and international cards everywhere else. Prices: ₹1199 / $11.99.

Is the data really verified?

Yes. Every quantitative claim — fabric capacity, queue counts, buffer sizes, timer ranges, default values, CLI verbs — was cross-checked against the live Juniper TechLibrary at write-time. Where a number couldn’t be authoritatively confirmed, the book explicitly says "consult the current datasheet" rather than fabricating a value.

Do I need a real EX4300 to do the labs?

No. Topologies are designed to run on real EX4300s, on EVE-NG with vMX/vQFX/vSRX images for L2 emulation, or on Juniper’s vSwitch images. Each lab note calls out the simulator caveats.

// start reading now

One purchase. Instant access. Lifetime updates.

No subscription, no monthly fee, no chapter-drip. Buy it once, read it forever, get every revision for free as Junos and the JNCIS-ENT blueprint evolve.

₹1199
or $11.99 USD
  • 18 chapters + 5 appendices unlocked
  • 7 hands-on labs & 60-question mock exam
  • 120-day access · free updates in-window
  • Mobile, tablet, desktop · no app required
  • Pay in ₹INR or $USD · secure via Razorpay

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