BGP
Border Gateway Protocol is the routing protocol that connects autonomous systems on the internet. It exchanges reachability information between networks so that traffic can find a path from any source to any destination across independently operated infrastructure.
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Don't Panic
Don't Panic - BGP
BGP is the subject of this course. The Internet is not one network. It is a network of networks, each run under its own policy.
The useful unit of work is a closed loop: clarify the goal and boundaries, gather the inputs the practice requires, make the decision or change, record evidence, and return with owners for the next cycle. Skipping any link leaves teams busy without durable results.
Tooling supports the loop; it does not replace it. Choose tools after the boundary and evidence model are clear. Comparing products without that model produces feature matrices that do not change how the work runs.
Common failure modes include undefined ownership, metrics that count activity instead of outcomes, and irreversible steps taken without a review path. Treat those as design defects in the practice, not as individual heroics to compensate later.
Operators should be able to explain which signals would change a decision this week. If no signal can change the plan, the practice has become ritual. Keep the feedback path short enough that evidence still influences the next cycle.
Name the owners for each stage of the loop before the work scales. Unowned stages become permanent exceptions. Record decisions with enough context that a future operator can tell why a tradeoff was accepted. Prefer fewer, sharper metrics that change behavior over broad dashboards that only describe activity after the fact.
Read the Intro for the core model. Use the Cheatsheet when you need the operating map. Updates tracks official guidance when this course configures an update source; otherwise the practice is settled without a live feed.
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See how this topic contributes to broader role-level skill maps.
Sources
- https://www.rfc-editor.org/rfc/rfc4271.html
Supports
- BGP as an inter-autonomous-system routing protocol
- Autonomous system, eBGP, iBGP, peer, route, prefix, and BGP speaker definitions
- TCP port 179 and OPEN, UPDATE, KEEPALIVE, and NOTIFICATION messages
- Incremental updates after initial routing exchange
- Adj-RIB-In, Loc-RIB, and Adj-RIB-Out conceptual stores
- AS_PATH loop detection and base path attributes
- LOCAL_PREF, MED, NEXT_HOP, ORIGIN, and decision-process behavior
- Full-mesh iBGP assumption and next-hop resolvability
- https://www.rfc-editor.org/rfc/rfc1997.html
Supports
- Communities as route labels used by policy
- NO_EXPORT, NO_ADVERTISE, and NO_EXPORT_SUBCONFED propagation behavior
- https://www.rfc-editor.org/rfc/rfc4456.html
Supports
- Route reflection as an alternative to full-mesh iBGP
- Route-reflector client and non-client behavior
- ORIGINATOR_ID and CLUSTER_LIST loop controls
- Best-path visibility and topology effects on route selection
- https://www.rfc-editor.org/rfc/rfc6793.html
Supports
- Expansion from two-octet to four-octet AS numbers
- Four-octet ASN capability negotiation
- AS4_PATH, AS4_AGGREGATOR, and AS_TRANS compatibility mechanisms
- https://www.rfc-editor.org/rfc/rfc7454.html
Supports
- Prefix and AS-path filtering by peer relationship
- Maximum-prefix limits and the need to review thresholds
- BGP session and control-plane protection
- Communities and next-hop filtering
- Layering route-origin validation with other operational controls
- https://www.rfc-editor.org/rfc/rfc8212.html
Supports
- Explicit import and export policy requirement for eBGP
- Received routes remaining ineligible without import policy
- Routes remaining absent from Adj-RIB-Out without export policy
- Permissive defaults as a route-leak risk
- https://www.rfc-editor.org/rfc/rfc6811.html
Supports
- Validated ROA payload fields
- Valid, Invalid, and NotFound origin-validation states
- Validation of prefix, length, and origin ASN
- Origin validation not providing complete AS-path attestation
- https://www.rfc-editor.org/rfc/rfc9234.html
Supports
- Route leaks as propagation contrary to expected relationships
- BGP Role capability and external peer relationship roles
- Only to Customer attribute for route-leak prevention and detection
