This object indicates the source from which the IP addr for
the subscriber is assigned.
pdpAddrSrcNone - None
pdpAddrSrcStatic - static address specified by the MS
pdpAddrSrcLocalPool - from the local pool
pdpAddrSrcRadius - from Radius server
pdpAddrSrcDhcp - from DHCP server
pdpAddrSrcIpcp - from Ipcp