What is a bogon, and why should I filter it?
A bogon prefix is a route that should never appear in the Internet routing table. A packet routed over the public Internet (not including over VPNs or other tunnels) should never have a source address in a bogon range. These are commonly found as the source addresses of DDoS attacks.Ref:http://www.team-cymru.org/Services/Bogons/
