Dell Force10 S4820T S4820T Configuration Guide - Page 186

www.dell.com | support.dell.com Figure 9-1. BGP Best Path Selection No, or Not Resulting in a Single Route Largest Highest Weight Local Pref Locally Originated Path Shortest AS Path Lowest Origin Code Lowest MED Learned Lowest via EBGP NEXT-HOP Cost Tie Breakers Short Cluster List from Lowest BGP ID Lowest Peering Addr A Single Route is Selected and Installed in the Forwarding Table Best Path selection details 1. Prefer the path with the largest WEIGHT attribute. 2. Prefer the path with the largest LOCAL_PREF attribute. 3. Prefer the path that was locally Originated via a network command, redistribute command or aggregate-address command. • Routes originated with the network or redistribute commands are preferred over routes originated with the aggregate-address command. 4. Prefer the path with the shortest AS_PATH (unless the bgp bestpath as-path ignore command is configured, then AS_PATH is not considered). The following criteria apply: • An AS_SET has a path length of 1, no matter how many ASs are in the set. • A path with no AS_PATH configured has a path length of 0. • AS_CONFED_SET is not included in the AS_PATH length. 186 | Border Gateway Protocol IPv4 (BGPv4)