When the value of vRtrMplsLspDecrementTtl is 'true', the ingress
ESR writes the TTL of the IP packet into the label and each
transit ESR decrements the TTL in the label. At the egress ESR
the TTL value from the label is written into the IP packet.
When the value of vRtrMplsLspDecrementTtl is 'false', the ingress
ESR ignores the IP packet TTL and writes the value of 255 into the
label; and the egress ESR does not write the label's TTL into the
IP packet.