Description: There are two types of OAM packets, CV and FFD. The CV flow is generated at the source LSR of the LSP with a nominal frequency of 1/s and terminated at the sink LSR of the LSP. FFD provides failure detection option for an LSP independent of the CV based availability model and is not tied to the CV insertion rate. Insertion rates at 1/s or faster may also be used. The CV/FFD packet contains a network-unique identifier (TTSI) so that all types of defects can be detected. 1: CV; 2: FFD.