0  1  2  3  4  5  6  7
+---------------------------------+    +--+--+--+--+--+--+--+--+
|  Flags (1 octet)                | -> |x |E |x |  T  |BM|U |L |
+---------------------------------+    +--+--+--+--+--+--+--+--+
|  Tunnel Type (1 octet)          |    T = Assisted Replication Type 
+---------------------------------+    BM = Broadcast and Multicast
|  MPLS Label (3 octets)          |    U = Unknown (unknown unicast)
+---------------------------------+    x = unassigned
|  Tunnel Identifier (variable)   |
+---------------------------------+