BMP v4: Extended TLV Support for BGP Monitoring Protocol (BMP)

Most of the BGP Monitoring Protocol (BMP) message types make provision for data in Type, Length, Value (TLV) format. However, Route Monitoring messages (which provide a snapshot of the monitored Routing Information Base) Stats Reports (which supply periodical counters) and Peer Down messages (which indicate that a peering session was terminated) do not. Supporting (optional) data in TLV format across all BMP message types provides consistent and extensible structures that would be useful among the various use- cases where conveying additional data to a monitoring station is required. This document updates RFC 7854 [RFC7854] to support TLV data in all message types and defines some essential TLVs. Additionally, this document introduces support for enterprise- specific TLVs in the BGP Monitoring Protocol by defining an Enterprise Bit (E-bit) that allows usage of per-vendor Type values.