Controls whether this circuit participates in a mesh group (a set of circuits treated as a virtual multiaccess network where LSPs received on one member circuit aren't re-flooded to another member, per RFC 2973): 'inactive' (default) means no mesh-group membership, 'set' enables it (with the group identified by isisCircMeshGroup), and 'blocked' disables flooding on this circuit entirely. An admin uses mesh groups to cut down redundant LSP flooding across a dense full-mesh topology such as a hub of parallel links to the same neighbor set.