Introduction to BGP

Just share that i learn from today.

ibgp batch updates sent once every 5 seconds
ebgp updates sent once every 30 seconds.
bgp uses port 179 and maintain neighbors or peer relationship

Hello messages sent once every 60 seconds with a holddown of 180 seconds. capable of md5 authentication.

######BGP Route Selection Criteria######
1. Exclude routes with inaccessible next hop
2. Prefer highest weight (Local to router)
3. Prefer highest local preference (global within AS)
4. Prefer routes that router originated
5. Prefer shortest AS Path(only length is compared)
6. Prefer Lowest Origin code (IGP < EGP < incomplete)
7.Prefer lowest MED
8. Prefer external (EBGP) paths over internal (IBGP)
9. For IBGP paths, prefer path through closet IGP neighbor
10. For EBGP paths, prefer oldest (most stable) path
11. Prefer paths from router with the lowest BGP router id