MIB_IPFORWARD_ROW2 structure

The MIB_IPFORWARD_ROW2 structure stores information about an IP route entry.

Syntax


typedef struct _MIB_IPFORWARD_ROW2 {
  NET_LUID          InterfaceLuid;
  NET_IFINDEX       InterfaceIndex;
  IP_ADDRESS_PREFIX DestinationPrefix;
  SOCKADDR_INET     NextHop;
  UCHAR             SitePrefixLength;
  ULONG             ValidLifetime;
  ULONG             PreferredLifetime;
  ULONG             Metric;
  NL_ROUTE_PROTOCOL Protocol;
  BOOLEAN           Loopback;
  BOOLEAN           AutoconfigureAddress;
  BOOLEAN           Publish;
  BOOLEAN           Immortal;
  ULONG             Age;
  NL_ROUTE_ORIGIN   Origin;
} MIB_IPFORWARD_ROW2, *PMIB_IPFORWARD_ROW2;

Members

InterfaceLuid

The locally unique identifier (LUID) for the network interface that is associated with this IP route entry.

InterfaceIndex

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

DestinationPrefix

The IP address prefix for the destination IP address for this route.

NextHop

For a remote route, the IP address of the next system or gateway that is along the route. If the route is to a local loopback address or an IP address on the local link, the next hop is unspecified (all zeros). For a local loopback route, this member should be an IPv4 address of 0.0.0.0 for an IPv4 route entry or an IPv6 address address of 0::0 for an IPv6 route entry.

SitePrefixLength

The length, in bits, of the site prefix or network part of the IP address for this route. For an IPv4 route entry, any value that is greater than 32 is an illegal value. For an IPv6 route entry, any value that is greater than 128 is an illegal value. A value of 255 is typically used to represent an illegal value.

ValidLifetime

The maximum time, in seconds, that the IP route entry is valid. A value of 0xffffffff is considered to be infinite.

PreferredLifetime

The preferred time, in seconds, that the IP route entry is valid. A value of 0xffffffff is considered to be infinite.

Metric

The route metric offset value for this IP route entry. Note the actual route metric that is used to compute the route preference is the interface metric that is specified in the Metric member of the MIB_IPINTERFACE_ROW structure added to the route metric offset that is specified in this Metric member. The semantics of this metric are determined by the routing protocol that is specified in the Protocol member. If this metric is not used, its value should be set to -1. This value is documented in RFC 4292. For more information, see IP Forwarding Table MIB.

Protocol

The NL_ROUTE_PROTOCOL routing mechanism type that this IP route was added with.

Loopback

A value that specifies if the route is a loopback route (the gateway is on the local host).

AutoconfigureAddress

A value that specifies if the IP address is autoconfigured.

Publish

A value that specifies if the route is published.

Immortal

A value that specifies if the route is immortal.

Age

The number of seconds since the route was added or modified in the network routing table.

Origin

A NL_ROUTE_ORIGIN IP route origin type.

Remarks

The GetIpForwardTable2 function enumerates the IP route entries on a local computer and returns this information in a MIB_IPFORWARD_TABLE2 structure as an array of MIB_IPFORWARD_ROW2 entries.

The GetIpForwardEntry2 function retrieves a single IP route entry and returns this information in a MIB_IPFORWARD_ROW2 structure.

An entry with the Prefix and the PrefixLength members of IP_ADDRESS_PREFIX set to zero in the DestinationPrefix member in the MIB_IPFORWARD_ROW2 structure is considered a default route. The MIB_IPFORWARD_TABLE2 might contain multiple MIB_IPFORWARD_ROW2 entries with the Prefix and the PrefixLength members of the IP_ADDRESS_PREFIX set to zero in the DestinationPrefix member when there are multiple network adapters installed.

The Metric member of a MIB_IPFORWARD_ROW2 entry is a value that is assigned to an IP route for a particular network interface that identifies the cost that is associated with using that route. For example, the metric can be valued in terms of link speed, hop count, or time delay. Automatic metric is a feature on Windows XP and later versions of the Windows operating systems that automatically configures the metric for the local routes that are based on link speed. By default, the automatic metric feature is enabled (the UseAutomaticMetric member of the MIB_IPINTERFACE_ROW structure is set to TRUE) on Windows XP and later. You can also manually configure this feature to assign a specific metric to an IP route.

The route metric that is specified in the Metric member of the MIB_IPFORWARD_ROW2 structure represents only the route metric offset. The complete metric is a combination of this route metric offset added to the interface metric that is specified in the Metric member of the MIB_IPINTERFACE_ROW structure of the associated interface. A driver can retrieve the interface metric by calling the GetIpInterfaceEntry function.

Requirements

Version

Available in Windows Vista and later versions of the Windows operating systems.

Header

Netioapi.h (include Netioapi.h)

See also

CreateIpForwardEntry2
DeleteIpForwardEntry2
GetIpForwardEntry2
GetIpForwardTable2
GetIpInterfaceEntry
IP_ADDRESS_PREFIX
MIB_IPFORWARD_TABLE2
MIB_IPINTERFACE_ROW
NL_ROUTE_ORIGIN
NL_ROUTE_PROTOCOL
SetIpForwardEntry2

 

 

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