R2 (Lo-18.104.22.168) ------ R3( Lo-22.214.171.124) ------ R4 (Lo-126.96.36.199)
MPLS TE - DYNAMIC between is created between R4-R2
mpls traffice-eng autoroute-announce
ip route 188.8.131.52 255.255.255.255 tunn42
They are both valid ways to use a TE tunnel as far as I know.
the first method advertises the tunnel into the IGP you are using in the core (OSPF or IS-IS)
the second method lets you statically use the tunnel
ultimately, which method you will use will depend on how the question is being asked .
Both are vaild methods of link admission.
But be sure to have static route on both ends of tunnel; i.e on R2 as well if
you want the traffic to traverse Tunnel in other direction too.
If autoroute announce configured then
for ipv6 mutli-topoly is required
for multicasting ---- mpls traffic-engi multicast-intact is required.