The value of tmnxL2tpTgMlpppEpIpv4Address specifies the
class 2 address to use in the MLPPP Endpoint Discriminator Option.
While the value of tmnxL2tpTgMlpppEpClass is equal to 'ipv4Address',
a value of all zeroes specifies that the system IP address be used;
otherwise, it means that no address is specified.