MIB_IPNET_ROW2 structure (netioapi.h)

  • Article

The MIB_IPNET_ROW2 structure stores information about a neighbor IP address.

Syntax

typedef struct _MIB_IPNET_ROW2 {
  SOCKADDR_INET     Address;
  NET_IFINDEX       InterfaceIndex;
  NET_LUID          InterfaceLuid;
  UCHAR             PhysicalAddress[IF_MAX_PHYS_ADDRESS_LENGTH];
  ULONG             PhysicalAddressLength;
  NL_NEIGHBOR_STATE State;
  union {
    struct {
      BOOLEAN IsRouter : 1;
      BOOLEAN IsUnreachable : 1;
    };
    UCHAR Flags;
  };
  union {
    ULONG LastReachable;
    ULONG LastUnreachable;
  } ReachabilityTime;
} MIB_IPNET_ROW2, *PMIB_IPNET_ROW2;

Members

Address

Type: SOCKADDR_INET

The neighbor IP address. This member can be an IPv6 address or an IPv4 address.

InterfaceIndex

Type: NET_IFINDEX

The local index value for the network interface associated with this IP address. This index value may change when a network adapter is disabled and then enabled, or under other circumstances, and should not be considered persistent.

InterfaceLuid

Type: NET_LUID

The locally unique identifier (LUID) for the network interface associated with this IP address.

PhysicalAddress[IF_MAX_PHYS_ADDRESS_LENGTH]

Type: UCHAR[IF_MAX_PHYS_ADDRESS_LENGTH]

The physical hardware address of the adapter for the network interface associated with this IP address.

PhysicalAddressLength

Type: ULONG

The length, in bytes, of the physical hardware address specified by the PhysicalAddress member. The maximum value supported is 32 bytes.

State

Type: NL_NEIGHBOR_STATE

The state of a network neighbor IP address as defined in RFC 2461, section 7.3.2. For more information, see http://www.ietf.org/rfc/rfc2461.txt. This member can be one of the values from the NL_NEIGHBOR_STATE enumeration type defined in the Nldef.h header file.

Value Meaning
NlnsUnreachable
 The IP address is unreachable.
NlnsIncomplete
 Address resolution is in progress and the link-layer address of the neighbor has not yet been determined. Specifically for IPv6, a Neighbor Solicitation has been sent to the solicited-node multicast IP address of the target, but the corresponding neighbor advertisement has not yet been received.
NlnsProbe
 The neighbor is no longer known to be reachable, and probes are being sent to verify reachability. For IPv6, a reachability confirmation is actively being sought by retransmitting unicast Neighbor Solicitation probes at regular intervals until a reachability confirmation is received.
NlnsDelay
 The neighbor is no longer known to be reachable, and traffic has recently been sent to the neighbor. Rather than probe the neighbor immediately, however, delay sending probes for a short while in order to give upper layer protocols a chance to provide reachability confirmation. For IPv6, more time has elapsed than is specified in the ReachabilityTime.ReachableTime member since the last positive confirmation was received that the forward path was functioning properly and a packet was sent. If no reachability confirmation is received within a period of time (used to delay the first probe) of entering the NlnsDelay state, then a neighbor solicitation is sent and the State member is changed to NlnsProbe.
NlnsStale
 The neighbor is no longer known to be reachable but until traffic is sent to the neighbor, no attempt should be made to verify its reachability. For IPv6, more time has elapsed than is specified in the ReachabilityTime.ReachableTime member since the last positive confirmation was received that the forward path was functioning properly. While the State is NlnsStale, no action takes place until a packet is sent.

The NlnsStale state is entered upon receiving an unsolicited neighbor discovery message that updates the cached IP address. Receipt of such a message does not confirm reachability, and entering the NlnsStale state insures reachability is verified quickly if the entry is actually being used. However, reachability is not actually verified until the entry is actually used.
NlnsReachable
 The neighbor is known to have been reachable recently (within tens of seconds ago). For IPv6, a positive confirmation was received within the time specified in the ReachabilityTime.ReachableTime member that the forward path to the neighbor was functioning properly. While the State is NlnsReachable, no special action takes place as packets are sent.
NlnsPermanent
 The IP address is a permanent address.
NlnsMaximum
 The maximum possible value for the NL_NEIGHBOR_STATE enumeration type. This is not a legal value for the State member.

IsRouter

Type: BOOLEAN

A value that indicates if this IP address is a router.

IsUnreachable

Type: BOOLEAN

A value that indicates if this IP address is unreachable.

Flags

Type: UCHAR

A set of flags that indicate whether the IP address is a router and whether the IP address is unreachable.

ReachabilityTime

ReachabilityTime.LastReachable

Type: ULONG The time, in milliseconds, that a node assumes a neighbor is reachable after having received a reachability confirmation.

ReachabilityTime.LastUnreachable

Type: ULONG The time, in milliseconds, that a node assumes a neighbor is unreachable after not having received a reachability confirmation.

Remarks

The MIB_IPNET_ROW2 structure is defined on Windows Vista and later.

The GetIpNetTable2 function enumerates the neighbor IP addresses on a local system and returns this information in an MIB_IPNET_TABLE2 structure.

For IPv4, this includes addresses determined used the Address Resolution Protocol (ARP). For IPv6, this includes addresses determined using the Neighbor Discovery (ND) protocol for IPv6 as specified in RFC 2461. For more information, see http://www.ietf.org/rfc/rfc2461.txt.

The GetIpNetEntry2 function retrieves a single neighbor IP address and returns this information in a MIB_IPNET_ROW2 structure.

Note that the Netioapi.h header file is automatically included in the Iphlpapi.h header file. The Netioapi.h header file should never be used directly.

Requirements

Requirement Value
Minimum supported client Windows Vista [desktop apps only]
Minimum supported server Windows Server 2008 [desktop apps only]
Header netioapi.h (include Iphlpapi.h)

See also

CreateIpNetEntry2

GetIpNetEntry2

GetIpNetTable2

MIB_IPNET_TABLE2

SOCKADDR_INET