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AR271 - pc_evans - 02-18-2024
The Router-ID is the tie breaker in the AS Path Selection. Path 6 wins because of its lowest Router-ID. Path 5 (RID 10.77.255.57) comes in second.
1. Weight - not a factor... no option mentions weight
2. Local Preference - Same value (100) on all paths
3. Origin Code - Same value (learned) on all paths.
4. Path Length - Same on all devices (1) an AS_Set counts as one
5. Origin ID - Same on all Devices (IGP)
6. MED - Same on all devices (0)
7. Prefer eBGP over iBGP - all paths are internal There is no distinction between Conferderation External and Confederation Internal.
8. IGP Metric - Same value (20645) on all paths.
9. Multipath - not used
10. if both paths are external, choose oldest path. not used
11. Lowest Router-ID Path 6 wins, Path 5 is second.
Changing the Local_Pref could have the desired effect but the wording is incorrect. Lowering the LOCAL_PREF does not select AS THE BEST PATH, you would need to raise the LOCAL_PREF for this to happen.
Prepending the AS_PATH for the current best path would move path 6 from first to worst. Path 5 would become the new best path.
https://www.cisco.com/c/en/us/support/docs/ip/border-gateway-protocol-bgp/13753-25.pdf
RE: AR271 - help_desk - 02-23-2024
The question has been corrected. Thank you!