1.6-BGP Best Path Algorithm

Question 1

How do you tag routes with the weight attribute in BGP?

Answer 1

In BGP you tag a route via the neighbor statement. The highest weight wins.

Weight: neighbor 172.16.0.1 weight 200

Question 2

What are the BGP Best Path Algorithms?

Answer 2

Cisco’s BGP Best Path Algorithm:

1. Weight: (Highest) Administrative preference.
2. Local Preference: (Highest) Communicated between peers
   within an AS.
3. locally originated: (True) Prefer paths originated locally.
4. Accumulated IGP (AIGP)
5. Shortest AS-Path: (Shortest) Minimize AS hops.