RST Forum's knowledge base is a free library of engineer-written guides on routing, switching, MPLS, VPNs, security, Linux and network automation. Every guide is a short book of chapters — written by the trainers who teach these subjects on real racks, and kept open for anyone to read.
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The core of the craft — from the OSI model to BGP path selection.
The OSI reference model is the seven-layer framework every networking conversation is built on. This guide walks the layers from physical signalling to application data, and shows how encapsulation actually moves a packet across a network.
How Ethernet switches actually forward traffic: MAC learning, flooding, VLANs and trunking — and how Spanning Tree Protocol keeps redundant layer-2 topologies from melting down into broadcast storms.
RIPv2 is the simplest IP routing protocol still worth studying: a distance-vector protocol that teaches the vocabulary — metrics, timers, split horizon, route poisoning — that every later protocol refines. Two chapters: how it works, and why its limits pushed the industry to EIGRP and OSPF.
Enhanced Interior Gateway Routing Protocol — Cisco's advanced distance-vector protocol, now an open standard. Four chapters cover the neighbour machinery, the composite metric, the DUAL algorithm that makes EIGRP loop-free by design, and the summarisation and stub features that make it scale.
Open Shortest Path First — the industry-standard link-state IGP. Four chapters build it up properly: link-state flooding and the LSDB, the neighbour state machine, the area system with its LSA types, and DR/BDR election with OSPF's network types.
Border Gateway Protocol — the path-vector protocol that routes the Internet and, increasingly, the data centre. Four chapters: how sessions and route exchange actually work, the full best-path selection order, policy control with communities and filters, and the scaling machinery of route reflectors and convergence tuning.
The 128-bit address architecture the Internet is migrating to: address types and notation, prefix planning, and the on-link machinery — Neighbor Discovery, SLAAC and DHCPv6 — that replaces ARP and re-thinks how hosts join a network.
One-to-many delivery done properly: how group membership works with IGMP, how PIM builds distribution trees through the routed network, and how sparse mode's rendezvous points make multicast scale from market-data feeds to IPTV.
Label switching, VPN backbones and the engineering of carrier cores.
Multiprotocol Label Switching — the forwarding architecture underneath almost every carrier backbone and enterprise WAN. Four chapters: why labels replaced longest-match lookups, how LDP distributes them, what the data plane really does with the stack, and how to verify the whole LSP end to end.
The flagship MPLS service: BGP/MPLS IP VPNs (RFC 4364), where one shared backbone carries thousands of customers' overlapping address spaces in isolated routing tables. Two chapters: the architecture — VRFs, route distinguishers, route targets — and the end-to-end control and forwarding path.
Carrying layer 2 itself across an MPLS core: point-to-point pseudowires that extend an Ethernet segment between two sites, and VPLS, which makes a whole provider network behave like one big switch — plus the EVPN successor that fixed both.
Making the network obey policy instead of shortest-path arithmetic: MPLS-TE tunnels that place traffic on explicitly computed paths with bandwidth reservations and fast reroute, and the QoS toolchain — classification, queuing, policing, shaping — that decides who suffers when links fill.
Filtering, translation and encrypted transport at the network edge.
The two edge tools every network still runs on: access control lists — ordered permit/deny filters evaluated top-down against packets — and network address translation, which stretched IPv4 far past its design life and complicates every protocol that embeds addresses.
Private networks over public transport: the IPsec framework — IKE negotiation, ESP encryption, tunnel and transport modes — and DMVPN, the hub-and-spoke overlay of mGRE and NHRP that lets branch offices build encrypted tunnels to each other on demand.
The Linux layer underneath servers, cloud and network tooling.
The operating system underneath servers, cloud instances and — increasingly — network devices themselves. Two working chapters: the filesystem, permissions and process model every engineer must navigate, and the networking toolkit for configuring and troubleshooting Linux hosts.
APIs, Python and controller-based networks — the CLI's successors.
Where the CLI era gives way to APIs and controllers: the automation stack — model-driven APIs, Python and Ansible — that treats network state as structured data, and Cisco SD-WAN, the controller-based overlay that replaced box-by-box WAN routing with centrally managed policy.
Our trainers' own lab sheets - topology, commands and verification output, lab by lab - across BGP, MPLS, SD-WAN, NSO, Linux and Python.
Every guide here pairs with an instructor-led course where the same topics are configured, broken and fixed on real equipment — classroom in Mumbai or live online.