IFEntry structure (tcpioctl.h)

[This structure may be altered or unavailable in future versions of Windows.]

Describes a TCP/IP interface in accord with the Simple Network Management Protocol, version 2, (SNMPv2) standard for Management Information Base for network management of TCP/IP networks (MIB-II), as specified in the Internet Engineering Task Force (IETF) Request for Comments (RFC) 1213 on pages 16 through 23.

Syntax

typedef struct IFEntry {
  ulong if_index;
  ulong if_type;
  ulong if_mtu;
  ulong if_speed;
  ulong if_physaddrlen;
  uchar if_physaddr[MAX_PHYSADDR_SIZE];
  ulong if_adminstatus;
  ulong if_operstatus;
  ulong if_lastchange;
  ulong if_inoctets;
  ulong if_inucastpkts;
  ulong if_innucastpkts;
  ulong if_indiscards;
  ulong if_inerrors;
  ulong if_inunknownprotos;
  ulong if_outoctets;
  ulong if_outucastpkts;
  ulong if_outnucastpkts;
  ulong if_outdiscards;
  ulong if_outerrors;
  ulong if_outqlen;
  ulong if_descrlen;
  uchar if_descr[1];
} IFEntry;

Members

if_index

A value between 1 and the number of network interfaces present on this system, regardless of their current state, that uniquely identifies this interface and persists across reinitialization of the network management system.

if_type

The interface type according to the physical or link protocol(s) immediately below the network layer in the protocol stack. The following table lists the possible values of this if_type member enumerated on pages 18 and 19 of RFC 1213.

Include the Ipifcons.h header file from the Microsoft SDK for flag constants supporting these and additional IP interface types.

When you examine the value of the if_type member, you may also want to define and test for an additional constant that identifies a "loopback" interface: #define IF_TYPE_LOOPBACK 0

if_mtu

The size, in bytes, of the largest datagram that can be sent or received on the interface. For interfaces that are used to transmit network datagrams, this is the size of the largest network datagram that can be sent on the interface.

if_speed

An estimate of the interface's current bandwidth, in bits per second. For interfaces that do not vary in bandwidth or for which no accurate estimation can be made, this member contains the nominal bandwidth.

if_physaddrlen

The length, in bytes, of the address contained in the if_physaddr member. For interfaces such as serial ports that do not have an address of this kind, the if_physaddrlen member is zero.

if_physaddr[MAX_PHYSADDR_SIZE]

The interface's address at the protocol layer immediately below the network layer in the protocol stack. For interfaces such as serial ports that do not have an address of this kind, the if_physaddr member contains an empty string.

if_adminstatus

The desired state of the interface; one of the following values specified on page 20 of RFC 1213.

if_operstatus

The actual current operational state of the interface; one of the following values specified on page 20 of RFC 1213.

if_lastchange

The time, in hundredths of a second, since the network management portion of the system was last reinitialized, at which this interface entered its actual current operational state. If the current state was entered prior to the last reinitialization of the local network management subsystem, this member is set to zero.

if_inoctets

The total number of bytes received on this interface, including framing characters.

if_inucastpkts

The number of subnetwork unicast packets delivered to a higher-layer protocol.

if_innucastpkts

The number of non-unicast (subnetwork broadcast or subnetwork multicast) packets delivered to a higher-layer protocol.

if_indiscards

The number of inbound packets that have been discarded to free up memory resources or for other similar reason not related to any error that would prevent their being deliverable to a higher-layer protocol.

if_inerrors

The number of inbound packets that have contained errors that prevent them from being deliverable to a higher-layer protocol.

if_inunknownprotos

The number of inbound packets that have been discarded because of an unknown or unsupported protocol.

if_outoctets

The total number of bytes transmitted out of the interface, including framing characters.

if_outucastpkts

The total number of packets that higher-level protocols have requested be transmitted to a subnetwork unicast address, including those that were discarded or not sent.

if_outnucastpkts

The total number of packets that higher-level protocols have requested be transmitted to a non-unicast (subnetwork broadcast or subnetwork multicast) address, including those that were discarded or not sent.

if_outdiscards

The number of outbound packets that have been discarded to free up memory resources or for other similar reasons not related to any error that would prevent their being transmitted.

if_outerrors

The number of outbound packets that could not be transmitted because of errors.

if_outqlen

The current number of packets in the output packet queue.

if_descrlen

The size, in bytes, not counting any terminating null character, of the interface description text contained in the if_descr member.

if_descr[1]

A text string that contains information about this interface, including the manufacturer's name, product name, and hardware version. If the string is not included, the size of the buffer is 1 byte.

Remarks

Because of its variable-length if_descr member, the IFEntry structure does not have a fixed size. For purposes of allocating memory to contain an actual instance of the structure, a reasonably safe buffer size can be computed as follows:

maxIFEntryLen = sizeof(IFEntry) + MAX_ADAPTER_DESCRIPTION_LENGTH + 1;

Requirements

See also

IOCTL_TCP_QUERY_INFORMATION_EX

Management Information Base Reference