Mastering BGP - Zero-to-Hero (2026 Updated)

Learn to configure basic eBGP peering among eight Cisco routers, form neighbor relationships, advertise networks with BGP, verify via show ip bgp summary, and observe path selection and route propagation.

Configure iBGP and eBGP peering across multiple autonomous systems, advertise connected networks, and examine path attributes and best-path selection using practical BGP commands.

Explore how to redistribute connected routes into a BGP process using route maps and ACLs to selectively advertise specific loopback networks, while contrasting network versus redistribution methods and origin codes.

Explore configuring eBGP multihop between non-direct neighbors using loopback addresses, set up static reachability, enable MD5 authentication, and verify iBGP and eBGP neighborships across a multi-router topology.

Implement eBGP md5 authentication to secure neighborships, configure password digests, and validate with show commands. Extend md5 authentication to R3–R5 and R4–R6 while advertising networks.

Learn iBGP fundamentals by building iBGP neighborships over a robust underlay using OSPF area zero, with loopback ten addresses known to all routers to preserve BGP attributes and AS path.

Configure ibgp neighborship between R2 and R3 using the loopback ten IP, ensuring underlay reachability. Apply update source loopback and next hop self to propagate routes reliably.

Configure next-hop self on iBGP peers to replace external next hops with the neighbor's address, enabling reachable routes and proper propagation of BGP updates.

Explore iBGP full mesh concepts and route reflectors, including split horizon, originator ID, cluster list, and next-hop self, to achieve scalable BGP convergence in labs.

Configure ibgp peer groups to simplify large BGP deployments. Apply common commands within the peer group and use route reflector client, update source loopback, next hop self, and md5 authentication.

Explore BGP route filtering using access lists and prefix lists, compare their network-portion matching and wildcard masks, and apply distribute lists for IGP and BGP updates.

Learn to implement BGP route filtering with ACLs and prefix lists, and apply as-path filters and route summarization. See lab examples for inbound and outbound filtering using distribute-list.

Learn to implement BGP route filtering with prefix lists, applying inbound and outbound policies, deny 11.0.0/8 and 15.0.0.0/8, and permit the remaining routes using prefix lists.

Master BGP route filtering with as-path filters and regular expressions, applying concise syntax such as caret, dollar, underscore, and dot-star to block or permit prefixes and prevent transit routes.

Explore BGP route aggregation, creating a single aggregate for loopbacks, and using prefix lists to advertise only the aggregate to a neighbor while keeping specific routes internal.

Learn BGP route aggregation with the summary only feature, using suppress and unsuppress map (and leak map) to selectively advertise aggregates and chosen prefixes.

Learn how BGP attributes guide traffic engineering in a multihomed topology by using next hop, local preference, weight, AS path, MED, and community to shape outbound and inbound traffic.

Explore the BGP attributes within a topology with multiple autonomous systems, including iBGP, eBGP, route reflectors, and next hop self, with practical lab guidance on loopbacks and neighbor configurations.

Learn how BGP path attributes, especially local preference within the ibgp domain, enable policy-based routing to influence outbound traffic and select the best exit path using route maps.

Learn how BGP's multi-exit discriminator (med) guides inbound traffic by assigning a metric to paths; set higher med to influence inbound routes while lower med remains preferred.

Master the BGP weight attribute, a Cisco proprietary, and learn to manipulate outbound traffic with locally significant weight that is not propagated, prioritizing weight over local preference in path selection.

Explore how the as path attribute prevents routing loops and enables traffic engineering by prepending as numbers to prefer the lowest as hop count across the BGP domain.

Tag BGP prefixes with the standard community attribute, then use no export and send community to keep routes within the AS and control propagation.

Explore how standard BGP communities govern route propagation with no export and no advertise, and implement per-prefix control using access lists, route maps, and neighbor configurations.

Explore advanced route reflector design in a multi-router BGP topology, separating control plane and data plane using R9 as route reflector and R1–R4 as servers.

Configure BGP dynamic neighborship to rapidly form ibgp peers via a route reflector, using listen ranges and authentication, with security considerations.

Configure BGP private autonomous systems in a customer-provider edge and advertise internal routes via iBGP, then remove private as when propagating to the public internet.

Configure bgp local-as to maintain private as peering while establishing public as peering, using a maintenance window and a pseudo as to preserve routes during transition.

Explore BGP confederation theory and configuration to simplify large networks by dividing an autonomous system into sub-AS, enabling iBGP with route reflectors, improved scalability, and granular policy control.

Explore advanced bgp confederations and route reflectors, configuring ibgp across 65001 to 65003 with loopback ten and multihop. Implement ebgp with confederation 1000, advertise loopback networks, and verify reachability.