| Description | An identification of the protocol being used by the application
on this interface. For an OSI Application, this will be the
Application Context. For Internet applications, the IANA
maintains a registry[22] of the OIDs which correspond to
well-known applications. If the application protocol is
not listed in the registry, an OID value of the form
{applTCPProtoID port} or {applUDProtoID port} are used for
TCP-based and UDP-based protocols, respectively. In either
case 'port' corresponds to the primary port number being
used by the protocol. The OIDs applTCPProtoID and
applUDPProtoID are defined in NETWORK-SERVICES-MIB |