BGP Route Selection & Peering
Routing
Overview
BGP exchanges network prefixes and attributes over established TCP sessions. Policy can prefer higher local preference before comparing AS-path length. Actual implementations have additional tie-breakers. This lesson uses a stated simplified ordering and does not claim a full vendor decision process.
Protocol stages
- 1TCP peering
- 2Prefix advertisement
- 3Import policy
- 4Local preference
- 5AS-path comparison
Interactive exercise
Knowledge check
Two valid routes: A local-pref 200, AS-path length 4; B local-pref 100, AS-path length 2. Under this ordering, choose?
Educational model — not real hardware, traffic or official certification.