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Connection-Oriented Timing Features

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Connection-oriented NDIS supports using a NIC's local time for scheduling the transmission of packets and for time-stamping send and receive packets.

Note  These connection-oriented timing features are optional. These features are not supported by all CoNDIS NICs.

A connection-oriented protocol driver can call NdisCoOidRequest to query the local timing capabilities of a connection-oriented miniport driver or an MCM driver with OID_GEN_CO_GET_TIME_CAPS. In response to such a query, the miniport driver or MCM driver returns information about:

  • Whether there is a readable clock on the NIC.

  • Whether the NIC derives its time from the network connection.

  • The precision of the local clock.

  • Whether the NIC can timestamp received packets with its local time.

  • Whether the NIC can schedule a send packet for transmission according to its local time.

  • Whether the NIC can timestamp transmitted packets with its local time.

To obtain a NIC's local time, a connection-oriented protocol can call NdisCoOidRequest to query a connection-oriented miniport driver or MCM driver with OID_GEN_CO_GET_NETCARD_TIME. The connection-oriented miniport driver or MCM driver synchronously returns its local time, which the connection-oriented protocol can then use to schedule the transmission of packets.

Timing information for a send or receive packet is contained in the packet's out-of-band (OOB) data. For more information, see NET_BUFFER_LIST.