BGP Communities Recognized by Cox Communications • Blackhole Filtering – Any traffic destined to a host/network with the 22773:666 community will be blackholed by Cox Communications. • Local Preference – The route sent by the customer to Cox Communications will, by default, have the BGP local preference set to 130. The communities below can be used to adjust that value. o 22773:125 – The local preference will be set to 125 instead. o 22773:120 – The local preference will be set to 120 instead. o 22773:110 – The local preference will be set to 110 instead. o 22773:90 – The local preference will be set to 90 instead. • More Specific Prefixes – Networks with prefix lengths >= 25 (i.e. /25, /26, /27, etc.) will be accepted if tagged with the 22773:65000 community. This may provide some benefits in a dual-homed scenario as a way influence the preferred path. Note that the more specific prefixes are not advertised beyond the Cox Communications market so the larger summary block should always be advertised. • Provider Suppression – Networks with the following communities will not be advertised to peers upstream to Cox Communications o 22773:10100 - A route tagged with this community will not be advertised out any peering sites. Only Cox Communications customers will receive routes tagged with this community. o 22773:10001 - A route tagged with this community will not be announced out any BGP peering connections with Level3. • Transit Providers for Cox Communications o NTT – To manipulate inbound traffic entirely through AS Path, if the 2914:470 community is applied by the route-policies facing Cox Communications, NTT will set a local preference of 100 to this route as it is advertised by Cox Communications and accepted into their network. The default local preference that NTT applies is 120, which would most likely make it the most desirable path to take, from the perspective of NTT, if the originating AS is multi-homed with other ISPs. With the 2914:470 community attached, NTT will now evaluate BGP routes using AS Path length, which is controlled by the originating AS. o Level3 / Centurylink - Level3 / Centurylink will set the local preference to 100 by default, so the AS Path length can be used to manipulate inbound traffic. However, if the community “3356:90” community is applied by the route-policies facing Cox Communications, Level3 / Centurylink will apply a local preference of 90 to this route as it is advertised by Cox Communications and accepted into their network, ensuring they would look towards your other upstream BGP provider for your inbound traffic.