BGP Large Community for Route Leak Detection

In general, BGP autonomous system (AS) relationships are either customer-transit or peer-peer. A route received from a transit or a peer can only be sent to a cust …

In general, BGP autonomous system (AS) relationships are either customer-transit or peer-peer. A route received from a transit or a peer can only be sent to a customer. If an AS sends such a route to a transit or a peer, it is considered a route leak. An AS may act as transit for some routes, but not others or in some regions, but not in others. Thus, AS relationships are sometimes different for different routes or in different regions. A method of detecting route leaks is proposed that does not require participation by the leaking AS or by IXPs. An IXP is not required to declare an AS relationship. A leaking AS is not required to recognize, set or transfer any new BGP attributes or communities. Only the ASes that request leak detection and ASes that perform leak detection need to adopt the proposal.