BGP Course

Lesson 1 • BGP Message Types and State Machine

Explains the four BGP message types and the finite state machine governing session establishment. Learners gain the mental model needed to diagnose session failures.

Lesson 2 • BGP Terminology and Key Attributes

Defines essential BGP vocabulary including AS numbers, prefixes, and path attributes. Accurate terminology is required for all subsequent configuration and troubleshooting topics.

Lesson 3 • Introduction to Interdomain Routing

Covers the need for routing between autonomous systems and why interior protocols are insufficient. Establishes the problem BGP solves before introducing its architecture.

Lesson 4 • BGP Tables and RIB Structure

Describes the Adj-RIB-In, Loc-RIB, and Adj-RIB-Out tables and how routes flow through them. Understanding RIB structure is essential for interpreting BGP routing decisions.

Lesson 1 • iBGP Full Mesh and Scalability Issues

Explains the iBGP full-mesh requirement and the scaling problems it creates in large networks. This problem motivates route reflectors and confederations covered in later chapters.

Lesson 2 • eBGP vs. iBGP Session Differences

Contrasts external and internal BGP peering rules, TTL behaviour, and next-hop handling. These distinctions drive different configuration requirements covered throughout the chapter.

Lesson 3 • Peer Groups and Dynamic Peering

Introduces peer groups to simplify repetitive neighbour configuration and reduce CPU overhead. Dynamic BGP peering concepts extend these efficiencies to large-scale deployments.

Lesson 4 • Configuring Basic BGP Neighbors

Walks through router BGP process creation, neighbour statements, and AS number assignment. Learners apply these steps to bring up their first functional BGP session.

Lesson 1 • Influencing Inbound Traffic with MED

Demonstrates how MED signals preferred entry points to neighbouring ASes for inbound traffic. Learners configure and verify MED in multi-homed scenarios.

Lesson 2 • Optional Transitive and Non-Transitive Attributes

Examines COMMUNITY, AGGREGATOR, and MED as optional attributes and their propagation rules. Understanding transitivity determines how attributes survive multi-hop BGP paths.

Lesson 3 • Influencing Outbound Traffic with LOCAL_PREF

Shows how LOCAL_PREF steers outbound traffic across multiple exit points within an AS. Learners apply LOCAL_PREF in route maps to achieve policy-based forwarding.

Lesson 4 • BGP Best-Path Selection Algorithm

Steps through the ordered decision process BGP uses to select one best path per prefix. Mastery of this sequence is required for all traffic engineering tasks.

Lesson 1 • Prefix Lists for Route Filtering

Introduces prefix lists as the preferred tool for matching specific prefixes and prefix lengths. Learners configure permit and deny entries and apply them to BGP neighbours.

Lesson 2 • AS_PATH Filtering with Regular Expressions

Covers AS_PATH access lists using regular expressions to match routes by origin or transit AS. This technique enables policy decisions based on routing path rather than prefix.

Lesson 3 • Soft Reconfiguration and Route Refresh

Explains how to apply policy changes without resetting BGP sessions using soft reconfiguration and route refresh. These mechanisms minimise disruption during policy updates.

Lesson 4 • Route Maps for Complex Policy

Demonstrates route maps as a multi-condition policy tool combining match and set clauses. Route maps enable attribute manipulation beyond simple permit or deny filtering.

Lesson 1 • Configuring and Verifying Confederations

Walks through confederation identifier, member AS, and peer configuration commands. Learners verify inter-sub-AS routing and attribute handling after configuration.

Lesson 2 • BGP Confederations Overview

Explains confederations as an alternative to route reflectors by subdividing an AS into sub-ASes. Learners compare confederation trade-offs against route reflector designs.

Lesson 3 • Configuring Route Reflectors

Provides step-by-step configuration of route reflector servers and clients on routers. Learners verify correct route propagation across the reflector topology.

Lesson 4 • Route Reflector Architecture and Design

Introduces route reflectors as a mechanism to eliminate the iBGP full-mesh requirement. Learners learn cluster design principles that prevent routing loops.

Lesson 1 • Standard BGP Communities

Defines the standard community attribute format and well-known community values. Learners configure community tagging and use communities to trigger downstream policies.

Lesson 2 • Multi-Homing Traffic Engineering Strategies

Combines LOCAL_PREF, MED, communities, and prepending to manage traffic across multiple upstream providers. Learners design and implement a complete multi-homed traffic policy.

Lesson 3 • Extended and Large Communities

Covers extended communities for VPN route targets and large communities for 32-bit AS environments. These formats extend community functionality beyond standard 32-bit values.

Lesson 4 • Community-Based Routing Policies

Demonstrates using received communities to apply LOCAL_PREF, MED, or filtering decisions. Community-based policy enables scalable, consistent control across large networks.

Lesson 1 • RPKI and Route Origin Validation

Explains the Resource Public Key Infrastructure framework and how ROAs validate prefix ownership. Learners configure route origin validation and understand RPKI state handling.

Lesson 2 • BGP Prefix Filtering Best Practices

Applies MANRS and operational community guidelines to inbound and outbound prefix filtering. Learners implement bogon filtering, max-prefix limits, and default route controls.

Lesson 3 • BGP Session and Control Plane Security

Addresses TCP session hardening, control plane policing, and infrastructure prefix protection. These measures reduce exposure to denial-of-service and session disruption attacks.

Lesson 4 • BGP Threat Landscape

Surveys route hijacking, route leaks, and prefix deaggregation attacks with real-world examples. Understanding attack vectors motivates the security controls introduced in this chapter.

Lesson 1 • BGP Performance and Convergence Tuning

Covers timer tuning, route dampening, and BGP graceful restart to improve stability and convergence. Learners balance fast convergence against route instability suppression.

Lesson 2 • Troubleshooting Missing or Incorrect Routes

Addresses scenarios where expected prefixes are absent or carry wrong attributes in the BGP table. Learners trace routes through the RIB pipeline to find filtering or policy errors.

Lesson 3 • Diagnosing BGP Session Failures

Covers common causes of stuck or flapping BGP sessions including misconfiguration and network issues. Learners use show and debug commands to identify and resolve session problems.

Lesson 4 • Structured BGP Troubleshooting Methodology

Introduces a layered diagnostic framework moving from physical connectivity to BGP policy. A consistent methodology reduces mean time to resolution in production incidents.