The value of tmnxL2tpTgMlpppEpClass specifies the
type of endpoint.
If the value of 'tmnxL2tpTgMlpppEpClass' is equal to 'ipv4Address',
the address for the MLPPP Endpoint Discriminator Option is taken from
tmnxL2tpTgMlpppEpIpv4Address.
If the value of 'tmnxL2tpTgMlpppEpClass' is equal to 'macAddress',
the address for the MLPPP Endpoint Discriminator Option is taken from
tmnxL2tpTgMlpppEpMacAddress.
If the value of 'tmnxL2tpTgMlpppEpClass' is equal to 'default',
the MLPPP Endpoint Discriminator Option must not be transmitted.
A value other than 'default' is only relevant for tunnels
where this system performs the LNS role.