This attribute indicates the required minimum level of security of
the trunks on the route. Zero represents the most secure and seven
represents the least secure. The trunk's security is indicated by the
trunkSecurity attribute of the Trunk component, and has values
identical in range and meaning to the requiredSecurity attribute.
PORS ensures that any route selected does not contain a trunk
whose trunkSecurity attribute is numerically greater than the
requiredSecurity.