The value of tmnxL2tpTuMlpppEpClass specifies the
type of endpoint.
If the value of 'tmnxL2tpTuMlpppEpClass' is equal to 'ipv4Address',
the address for the MLPPP Endpoint Discriminator Option is taken from
tmnxL2tpTuMlpppEpIpv4Address.
If the value of 'tmnxL2tpTuMlpppEpClass' is equal to 'macAddress',
the address for the MLPPP Endpoint Discriminator Option is taken from
tmnxL2tpTuMlpppEpMacAddress.
The value 'default' specifies that the actual value must be used
of the object tmnxL2tpTgMlpppEpClass of the tunnel group
this tunnel configuration belongs to.
A value other than 'default' is only relevant for tunnels
where this system performs the LNS role.