Juniper Logical Systems on vMX — Free 15-Video Course

What if you could run a full service provider lab topology — nine routers, five OSPF areas, a complete iBGP and eBGP mesh — on a single Juniper vMX image, on your own PC, without spending a penny on additional hardware?

That is exactly what this free fifteen-video course teaches you to do. Juniper logical systems let you split a single physical or virtual device into up to fifteen completely independent virtual routers, each with its own routing tables, its own routing protocols, and its own router ID. The result is a realistic multi-protocol lab environment that would normally require a rack full of hardware — running comfortably on six CPU cores and eight gigabytes of RAM.

This course takes you through the full build from scratch. By the time you reach the final video you will have configured logical tunnel interfaces, OSPF multi-area routing with authentication and BFD, internal and external BGP with route policy, and a next-hop-self fix for iBGP route propagation — all inside one vMX. The topology mirrors real service provider network design and every concept covered applies directly to working with physical Juniper hardware in production.

What Are Juniper Logical Systems?

Logical systems are a Juniper feature available on MX series routers and some other platforms that allows a single device to be partitioned into multiple independent virtual routers. If you have studied routing instances as part of your JNCIA preparation, logical systems take that concept significantly further.

A routing instance gives you a separate routing table. A logical system gives you a complete independent router — its own routing table, its own routing protocol instances, its own router ID, its own user management, and complete isolation from every other logical system on the same device. From a configuration and operational perspective each logical system behaves exactly like a standalone physical router.

In this course we run nine logical systems simultaneously on a single vMX — CE1, PE1, PE2, PE3, PE4, a core router, and supporting devices. Running the same topology as nine separate vMX instances would require over 70 gigabytes of RAM. As a single device with logical systems it runs comfortably on hardware most engineers already have at home. Logical systems support OSPF, ISIS, BGP, MPLS, RSVP, LDP, EVPN, L2VPN, L3VPN and more — everything you need for serious service provider lab study.

What You Will Build

The course builds a complete service provider topology step by step. Each video adds a layer of configuration to the same running lab so by the end you have a fully functional multi-protocol network rather than a series of disconnected demos. The finished topology includes nine virtual routers running inside a single Juniper vMX image, logical tunnel interfaces connecting all PE routers to each other and to the core, OSPF multi-area configuration across five areas with PE routers acting as ABRs, MD5 authentication on all PE-to-PE OSPF links, simple password authentication on PE-to-core links, BFD configured for sub-second OSPF failure detection, iBGP between four PE routers sourced from loopback addresses, eBGP between PE1 and CE1 with route policy for prefix advertisement, a next-hop-self policy to fix iBGP route propagation across the core, and user accounts scoped to individual logical systems for access control.

All configuration files are provided for download at key stages throughout the series so you can import any point in the build directly without having to replay every previous step.

What You Will Learn

Logical Systems Fundamentals — how logical systems differ from routing instances, navigating between logical systems using set CLI logical-system, the difference between global configuration and per-logical-system configuration, and creating logical systems from scratch.

Logical Tunnel Interfaces — enabling tunnel services on the vMX chassis under FPC and PIC, creating LT sub-interfaces with Ethernet encapsulation, binding tunnels together with the peer-unit command, and understanding why logical systems have completely separate routing tables.

OSPF — configuring OSPF area 0 across the full PE mesh, passive loopbacks and active tunnel interfaces, multi-area OSPF with CE routers in separate areas, ABR behaviour and type 3 summary LSA generation, MD5 and simple password authentication, BFD liveness detection with minimum interval and multiplier, and real-time log monitoring with traceoptions.

BGP — setting autonomous system numbers, iBGP group configuration with loopback-sourced sessions, why iBGP uses loopbacks and eBGP uses interface addresses, the TTL-1 restriction on external BGP, route policy for prefix advertisement, understanding why BGP advertises nothing without explicit policy, hidden routes and what causes them, next-hop-self policy to fix iBGP propagation, and iBGP split horizon behaviour.

Who Is This Course For?

This course is aimed at network engineers who already have a working knowledge of JunOS fundamentals — the kind of knowledge you would have from JNCIA level study or practical experience with Juniper equipment. You should be comfortable with the JunOS CLI, understand configuration mode, and know what commit means before starting.

It is particularly well suited to engineers studying for JNCIS-SP or JNCIS-ENT who want a practical lab environment for hands-on study, engineers working towards JNCIP or CCIE Service Provider level who need to practice multi-protocol service provider topologies, engineers working with Juniper equipment in production who want to deepen their understanding of OSPF and BGP, and anyone limited by hardware or cloud lab costs who needs a high-density lab on modest hardware.

You do not need to be an expert in BGP or OSPF before starting. Each protocol is introduced and configured from scratch within the context of the topology, with clear explanations of what is happening and why at each step.

The Lab Environment

The entire course runs on a single Juniper vMX image in EVE-NG or GNS3 — both are used across the series so you can follow along with whichever platform you have available. The recommended minimum is six CPU cores and eight gigabytes of RAM allocated to the vMX. The course demonstrates this running on a home PC with these specifications, proving a realistic service provider lab is achievable without dedicated hardware.

Course Contents

1. Juniper Logical Systems on vMX — What They Are and How to Set Them Up
2. Enabling Tunnel Services and LT Interfaces
3. Basic Tunnel Configuration to Bind Virtual Routers
4. Core Configuration Walkthrough
5. Configuring User Accounts Per Logical System
6. Debugging and Log File Configuration
7. Configuring OSPF Between Virtual Routers
8. OSPF MD5 Authentication Configuration
9. OSPF Simple Password Authentication
10. Configuring BFD for OSPF
11. Inter-Area OSPF Configuration
12. Full OSPF Configuration Walkthrough
13. First BGP Configuration — iBGP Between PE Routers
14. eBGP to eBGP Configuration
15. BGP Route Advertisement and Next-Hop-Self

Completely Free

All fifteen videos are completely free. No sign-up, no email required, nothing held back. Watch them here or on the YouTube channel — the content is identical either way.

If you want to go further with Juniper certification preparation, the JNCIA JN0-104 and JNCIS-SP JN0-363 courses are both available on Udemy — links in the video descriptions. But there is no obligation and this series stands completely on its own as a practical lab course.