This document has been extracted from bordergateproto.pdf.

Verizon Community Strings

Verizon Internet Dedicated customers that run BGP can send community strings with their route advertisements to modify the Verizon Local Preference, increase the AS path length, control which routes are advertised to peers, contain routes within a continental AS, or black hole (drop) traffic at the Verizon network edge, to reduce the impact of a DDoS attack.

   The following table lists the community tags that would be used for AS 701, associated BGP attribute and value (if applicable), and resulting action.

Community TagAttributeValueAction
701:80Local Pref80Least preferred
701:90Local Pref90Less preferred
701:100Local Pref100Default
701:110Local Pref110More preferred
701:120Local Pref120Most preferred
701:1AS Path701 701Prepend the Verizon AS 701 one time
701:2AS Path701 701 701Prepend the Verizon AS 701 two times
701:3AS Path701 701 701 701Prepend the Verizon AS 701 three times
701:20  Keep route within Verizon Autonomous Systems (do not send to peers)
701:30  Refer to Note (keep route within regional Verizon AS and do not send to peers)
701:9999  Refer to Note (black hole the route at Verizon network edge devices)

Table A-1

Note 1: Verizon has several AS numbers assigned to different regions of the world:

701North America
702Europe/Middle East/Africa
14551Latin America/South America

The AS portion of the community tag values should be changed appropriately for use in different Verizon regions.

Note 2: For technical reasons, customers who wish to use the black hole community must enable EBGP multihop (although BGP is still configured between the circuit addresses).

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