In case this interface is connected to a VPLS via a CCA (Cross Connect
Adaptor) MDA, the value of tmnxPppoeIesIfDhcpcCcagOriginSap specifies
whether the system includes the original VPLS SAP in the circuit-id
option to send to the DHCP server(s).
In case of a retailer interface, the value of this object is
irrelevant, and setting it (to a value other than false) is not
allowed.