Building the BGP Table - Injecting Routes/Prefixes into the BGP table - Determining the Contents of Updates

4 important questions on Building the BGP Table - Injecting Routes/Prefixes into the BGP table - Determining the Contents of Updates

How does BGP determine the best route? 4

1. Choose the route with shortest AS_PATH
2. If AS_PATH is a tie, prefer eBGP over iBGP routes
3. If route has not been chosen, choose route with lowest IGP metric to NEXT_HOP route
4. If metric ties, choose iBGP-learned route with lowest BGP RID of advertising router

What is the default action for advertised routes with eBGP?

Change the NEXT_HOP to the update source IP address

What is the eBGP command to switch to other behavior of the next hop?

Neighbor.... next-hop-unchanged
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Which routes does BGP not include in an update?

iBGP/eBGP routes that are not considered  "best"
iBGP/eBGP routes matched by a deny clause in an outbound filter
iBGP iBGP-learned routes

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