The type/protocol of interface. Specification of the object is mandatory for all interfaces. This value should be specified after the row creation in the ifMainTable and before setting any other object in this table. Once the type is specified, it cannot be changed - the interface should be deleted for changing the type of the interface. The ethernetCsmacd(6), iso88025TokenRing(9), aal5(49), async(84) and hdlc(118) are physical interfaces while all other types are virtual or logical interfaces. Specific ifIndex ranges are reserved for different interface types. Creation of different types of interfaces is possible only within their corresponding ifIndex range. So the ifMainType should be configured corresponding to the ifIndex range reserved for that particular interface type. For creation of physical interface types, it is mandatory to specify the handle to the device driver using the ifAlias object of the standard ifXTable before specifying the type. This handle could be something like eth1 or /dev/abcd. pip interface type will be used vritual Provider Instance port in PBB bridge mode. physical PIPs can be created using ethernetCsmacd . Following is the mapping of different port types and there ifmaintype values. External ports Port: ifmaintype Port type CNP- Ctagged 6 - customerNetworkPortCtagged (9) CNP - Port based 6 - customerNetworkPortPortBased (2) CNP- Stagged 6 - customerNetworkPortStagged (3) PNP 6 - providerNetworkPort (1) PIP 6 - providerInstancePort (11) CBP 6 - customerBackbonePort (12) Internal ports VIP 209 - virtualInstancePort (10) PIP 248 - providerInstancePort (11) CBP 209 - customerBackbonePort (12) brgPort will be used to create virtual PBB ports other than PIPs- VIPs and CBPs. The propVirtual type denotes properietary logical interfaces. These type of interfaces can be associated with a {physical interface, switch instance} for the purpose of sharing the physical interface to more than one context and thus realising Switch Instance Sharing of a physical interface.