This object indicates which routing protocol a TC is
being controlled by.
'static'
TC is controlled by static routing protocol.
'eigrp'
TC is controlled by EIGRP.
'ribpbr'
TC is controlled by RIB.
'bgp'
TC is controlled by BGP
'pbr'
TC is controlled by PBR.
'cce'
TC is controlled by CCE.
'unknown'
TC os controlled by unknown protocols