telia.com/twelve99.net/arelion.com的官方社区参数， 电信的全球默认出口

https://www.arelion.com/our-network/bgp-routing/bgp-communities

cogent的社区参数收集

Do not export outside AS 174

174:990 Global: Do not send route to BGP customers, or peers.
174:980 Do not export outside AS174 in EU (Europe) Region
174:970 Do not export outside AS174 in NA (North America)
174:960 Do not export outside AS174 in AP (Asia Pacific) Region
174:950 Do not export outside AS174 in SA (South America)
174:940 Do not export outside AS174 in AU (Australia) Region
174:930 Do not export outside AS174 in AF (Africa) Region

Do not send to private peers

174:991 Global: Do not send route to peers.
174:981 Do not send to AS174 private peers in EU Region
174:971 Do not send to AS174 private peers in NA Region
174:961 Do not send to AS174 private peers in AP Region
174:951 Do not send to AS174 private peers in SA Region
174:941 Do not send to AS174 private peers in AU Region
174:931 Do not send to AS174 private peers in AF Region

Do not export prefixes between Cogent regions

174:982 Set localpref to 10 upon entering EU Region from other regions of the Cogent backbone
174:972 Set localpref to 10 upon entering NA Region fromother regions of the Cogent backbone
174:962 Set localpref to 10 upon entering AP Region fromother regions of the Cogent backbone
174:952 Set localpref to 10 upon entering SA Region fromother regions of the Cogent backbone
174:942 Set localpref to 10 upon entering AU Region fromother regions of the Cogent backbone
174:932 Set localpref to 10 upon entering AF Region

Prepending Communities

174:3000 Do not announce to peers (equivalent to 174:991)
174:3001 Prepend 174 1 time to peers.
174:3002 Prepend 174 2 times to peers.
174:3003 Prepend 174 3 times to peers.

HE 的只有个666黑洞，其他的参数未公开过

未完待续