The Encapsulation type for the Vlan Cluster
service.
1 = RFC 1483 encapsulation.
2 = Xylan ATM trunking.
3 = not applicable.
This object is only valid for Vlan cluster
services. All other ATM services will return
a value of 3.
If the encapsulation type is RFC 1483, only
one (1) vlan as defined in atmxServiceVlan
can be associated with this service. If
encapsulation type is Xylan ATM trunking more
than 1 vlan can be assocated with this service.