Loop prevention mechanism on BGP routing

Presentation on BGP protocol

1. Presentation (Topic: Loop Prevention Mechanism in BGP) Presented By Arafat Ashrafi Talha Student ID: BWU/MNC/22/006 Course Name: Routing Professional Course Code: MNCS301 D epartment of Cyber Science & Technology

2. Introduction: BGP (Border Gateway Protocol) is a path vector routing protocol used to exchange routing information between Autonomous Systems ( ASes ). BGP does not maintain a complete topology of the network, but instead relies on the AS_PATH attribute to track the path that a route has taken to reach it. This attribute contains a list of all AS numbers that the route has traversed.

3. WHAT IS LOOP PREVENTION? Loop prevention in networking is a feature that prevents loops from forming. Loops can cause network instability, congestion, and performance degradation

4. BGP loop prevention mechanisms: AS_PATH attribute Split horizon rule cloud

5. AS_PATH Attribute: The AS_PATH attribute is a mandatory attribute in BGP updates. It contains a list of all AS numbers that the route has traversed to reach the advertising router. When a BGP router receives an update, it compares the AS_PATH attribute of the update to its own AS number. If the BGP router sees its own AS number in the AS_PATH attribute, it discards the update. This prevents loops from forming in the BGP network.

6. Split Horizon Rule: The split horizon rule states that a BGP router should not advertise a route to a neighbor from which it learned the route. This prevents loops from forming in the BGP network, even if the AS_PATH attribute is not properly configured.

7. Loop Prevention in IBGP and EBGP : The loop prevention mechanisms described above apply to both IBGP (Interior BGP) and EBGP (Exterior BGP). IBGP is used to exchange routing information between routers within the same AS. EBGP is used to exchange routing information between routers in different ASes .

8. Loop Prevention in IBGP : In IBGP, the split horizon rule is the primary loop prevention mechanism. This is because all IBGP peers have the same AS number, so the AS_PATH attribute cannot be used to prevent loops.

9. Loop Prevention in EBGP : In EBGP, the AS_PATH attribute is the primary loop prevention mechanism. This is because each EBGP peer has a unique AS number, so the AS_PATH attribute can be used to track the path that a route has taken to reach the advertising router.

10. Conclusion: BGP loop prevention mechanisms are essential for preventing routing loops from forming in the BGP network. Without loop prevention, routing loops can cause network congestion, outages, and other problems.

11. THANK YOU