There are multiple independent interoperable implementations of BGP currently available. This section gives a brief overview of the implementations that are currently used in the operational Internet. They are:
To facilitate efficient BGP implementations, and avoid commonly made mistakes, the implementation experience with BGP-4 in with cisco's implementation was documented as part of RFC 1656 [4].
Implementors are strongly encouraged to follow the implementation suggestions outlined in that document and in the appendix of [2].
Experience with implementing BGP-4 showed that the protocol is relatively simple to implement. On the average BGP-4 implementation takes about 2 man/months effort, not including any restructuring that may be needed to support CIDR.
Note that, as required by the IAB/IESG for Draft Standard status, there are multiple interoperable completely independent implementations.