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MIB_IPFORWARDROW structure

The MIB_IPFORWARDROW structure contains information that describes an IPv4 network route.

Syntax


typedef struct _MIB_IPFORWARDROW {
  DWORD dwForwardDest;
  DWORD dwForwardMask;
  DWORD dwForwardPolicy;
  DWORD dwForwardNextHop;
  DWORD dwForwardIfIndex;
  DWORD dwForwardType;
  DWORD dwForwardProto;
  DWORD dwForwardAge;
  DWORD dwForwardNextHopAS;
  DWORD dwForwardMetric1;
  DWORD dwForwardMetric2;
  DWORD dwForwardMetric3;
  DWORD dwForwardMetric4;
  DWORD dwForwardMetric5;
} MIB_IPFORWARDROW, *PMIB_IPFORWARDROW;

Members

dwForwardDest

Type: DWORD

The destination IPv4 address of the route. An entry with a IPv4 address of 0.0.0.0 is considered a default route. This member cannot be set to a multicast (class D) IPv4 address.

dwForwardMask

Type: DWORD

The IPv4 subnet mask to use with the destination IPv4 address before being compared to the value in the dwForwardDest member.

The dwForwardMask value should be applied to the destination IPv4 address (logical and operation) before a comparison with the value in the dwForwardDest member.

dwForwardPolicy

Type: DWORD

The set of conditions that would cause the selection of a multi-path route (the set of next hops for a given destination). This member is typically in IP TOS format. This encoding of this member is described in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt.

dwForwardNextHop

Type: DWORD

For remote routes, the IPv4 address of the next system en route. Otherwise, this member should be an IPv4 address of 0.0.0.0.

dwForwardIfIndex

Type: DWORD

The index of the local interface through which the next hop of this route should be reached.

dwForwardType

Type: DWORD

The route type as described in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt.

This member can be one of the values defined in the Iprtmib.h header file.

On Windows Vista and later, the header files were reorganized and this member can be one of the values from the MIB_IPFORWARD_TYPE enumeration type defined in the Ipmib.h header file. Note that the Ipmib.h header is automatically included by the Iprtrmib.h header file which is automatically included by the Iphlpapi.h header. The Iprtrmib.h and Ipmib.h header files should never be used directly.

The following list shows the possible values for this member.

ValueMeaning
MIB_IPROUTE_TYPE_OTHER
1

Some other type not specified in RFC 1354.

MIB_IPROUTE_TYPE_INVALID
2

An invalid route. This value can result from a route added by an ICMP redirect.

MIB_IPROUTE_TYPE_DIRECT
3

A local route where the next hop is the final destination (a local interface).

MIB_IPROUTE_TYPE_INDIRECT
4

The remote route where the next hop is not the final destination (a remote destination).

 

dwForwardProto

Type: DWORD

The protocol or routing mechanism that generated the route as described in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt. See Protocol Identifiers for a list of possible protocol identifiers used by routing protocols.

This member can be one of the values defined in the Iprtmib.h header file. The values for this member can be one of the MIB_IPPROTO_xxx values defined in the Iprtmib.h header file or one of the PROTO_IP_xxx values defined in the routprot.h header file since these values are the same.

On Windows Vista and later, the header files were reorganized and this member can be one of the values defined in the Nldef.h header file. Note that the Nldef.h header is automatically included by the Ipmib.h header file which is automatically included by the Iprtrmib.h header. The Iphlpapi.h header automatically includes the Iprtrmib.h header file. The Iprtrmib.h, Ipmib.h, and Nldef.h header files should never be used directly.

The following list shows the possible values for this member.

ValueMeaning
MIB_IPPROTO_OTHER
1

Some other protocol not specified in RFC 1354.

MIB_IPPROTO_LOCAL
2

A local interface.

MIB_IPPROTO_NETMGMT
3

A static route. This value is used to identify route information for IP routing set through network management such as the Dynamic Host Configuration Protocol (DCHP), the Simple Network Management Protocol (SNMP), or by calls to the CreateIpForwardEntry, DeleteIpForwardEntry, or SetIpForwardEntry functions.

MIB_IPPROTO_ICMP
4

The result of ICMP redirect.

MIB_IPPROTO_EGP
5

The Exterior Gateway Protocol (EGP), a dynamic routing protocol.

MIB_IPPROTO_GGP
6

The Gateway-to-Gateway Protocol (GGP), a dynamic routing protocol.

MIB_IPPROTO_HELLO
7

The Hellospeak protocol, a dynamic routing protocol. This is a historical entry no longer in use and was an early routing protocol used by the original ARPANET routers that ran special software called the Fuzzball routing protocol, sometimes called Hellospeak, as described in RFC 891 and RFC 1305. For more information, see http://www.ietf.org/rfc/rfc891.txt and http://www.ietf.org/rfc/rfc1305.txt.

MIB_IPPROTO_RIP
8

The Berkeley Routing Information Protocol (RIP) or RIP-II, a dynamic routing protocol.

MIB_IPPROTO_IS_IS
9

The Intermediate System-to-Intermediate System (IS-IS) protocol, a dynamic routing protocol. The IS-IS protocol was developed for use in the Open Systems Interconnection (OSI) protocol suite.

MIB_IPPROTO_ES_IS
10

The End System-to-Intermediate System (ES-IS) protocol, a dynamic routing protocol. The ES-IS protocol was developed for use in the Open Systems Interconnection (OSI) protocol suite.

MIB_IPPROTO_CISCO
11

The Cisco Interior Gateway Routing Protocol (IGRP), a dynamic routing protocol.

MIB_IPPROTO_BBN
12

The Bolt, Beranek, and Newman (BBN) Interior Gateway Protocol (IGP) that used the Shortest Path First (SPF) algorithm. This was an early dynamic routing protocol.

MIB_IPPROTO_OSPF
13

The Open Shortest Path First (OSPF) protocol, a dynamic routing protocol.

MIB_IPPROTO_BGP
14

The Border Gateway Protocol (BGP), a dynamic routing protocol.

MIB_IPPROTO_NT_AUTOSTATIC
10002

A Windows specific entry added originally by a routing protocol, but which is now static.

MIB_IPPROTO_NT_STATIC
10006

A Windows specific entry added as a static route from the routing user interface or a routing command.

MIB_IPPROTO_NT_STATIC_NON_DOD
10007

A Windows specific entry added as a static route from the routing user interface or a routing command, except these routes do not cause Dial On Demand (DOD).

 

dwForwardAge

Type: DWORD

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

dwForwardNextHopAS

Type: DWORD

The autonomous system number of the next hop. When this member is unknown or not relevant to the protocol or routing mechanism specified in dwForwardProto, this value should be set to zero. This value is documented in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt

dwForwardMetric1

Type: DWORD

The primary routing metric value for this route. The semantics of this metric are determined by the routing protocol specified in the dwForwardProto member. If this metric is not used, its value should be set to -1. This value is documented in in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt

dwForwardMetric2

Type: DWORD

An alternate routing metric value for this route. The semantics of this metric are determined by the routing protocol specified in the dwForwardProto member. If this metric is not used, its value should be set to -1. This value is documented in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt

dwForwardMetric3

Type: DWORD

An alternate routing metric value for this route. The semantics of this metric are determined by the routing protocol specified in the dwForwardProto member. If this metric is not used, its value should be set to -1. This value is documented in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt

dwForwardMetric4

Type: DWORD

An alternate routing metric value for this route. The semantics of this metric are determined by the routing protocol specified in the dwForwardProto member. If this metric is not used, its value should be set to -1. This value is documented in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt

dwForwardMetric5

Type: DWORD

An alternate routing metric value for this route. The semantics of this metric are determined by the routing protocol specified in the dwForwardProto member. If this metric is not used, its value should be set to -1. This value is documented in RFC 1354. For more information, see http://www.ietf.org/rfc/rfc1354.txt

Remarks

The GetIpForwardTable function enumerates the IPv4 route entries on a local system and returns this information in a MIB_IPFORWARDTABLE structure that contains an array of MIB_IPFORWARDROW structure entries.

The dwForwardDest, dwForwardMask, and dwForwardNextHop members of the MIB_IPFORWARDROW structure represent IPv4 addresses in network byte order.

The dwForwardProto member of the MIB_IPFORWARDROW structure specifies the protocol or routing mechanism that generated the route. Routing protocol identifiers are used to identify route information for the specified routing protocol. For example, MIB_IPPROTO_NETMGMT is used to identify route information for IP routing set through network management such as the Dynamic Host Configuration Protocol (DCHP), the Simple Network Management Protocol (SNMP), or by calls to the CreateIpForwardEntry, DeleteIpForwardEntry , or SetIpForwardEntry functions. See Protocol Identifiers for a list of possible protocols and routing mechanisms.

An IPv4 address of 0.0.0.0 in the dwForwardDest member of the MIB_IPFORWARDROW structure is considered a default route. The MIB_IPFORWARDTABLE may contain multiple MIB_IPFORWARDROW entries with the dwForwardDest member set to 0.0.0.0 when there are multiple network adapters installed.

When dwForwardAge is set to INFINITE, the route will not be removed based on a timeout value. Any other value for dwForwardAge specifies the number of seconds since the route was added or modified in the network routing table.

On Windows Server 2003 or Windows 2000 Server when the Routing and Remote Access Service (RRAS) is running, the MIB_IPFORWARDROW entries returned have the dwForwardType and dwForwardAge members set to zero.

On Windows Vista and Windows Server 2008, the route metric specified in the dwForwardMetric1 member of the MIB_IPFORWARDROW structure represents a combination of the route metric added to the interface metric specified in the Metric member of the MIB_IPINTERFACE_ROW structure of the associated interface. So the dwForwardMetric1 member of the MIB_IPFORWARDROW structure should be equal to or greater than Metric member of the associated MIB_IPINTERFACE_ROW structure. If an application would like to set the route metric to 0, then the dwForwardMetric1 member of the MIB_IPFORWARDROW structure should be set equal to the value of the interface metric specified in the Metric member of the associated MIB_IPINTERFACE_ROW structure. An application can retrieve the interface metric by calling the GetIpInterfaceEntry function.

A number of members of the MIB_IPFORWARDROW structure are not currently used by IPv4 routing. These members include dwForwardPolicy, dwForwardNextHopAS, dwForwardMetric2, dwForwardMetric3, dwForwardMetric4, and dwForwardMetric5.

On the Microsoft Windows Software Development Kit (SDK) released for Windows Vista and later, the organization of header files has changed. This structure is defined in the Ipmib.h header file, not in the Iprtrmib.h header file. Note that the Ipmib.h header file is automatically included in Iprtrmib.h, which is automatically included in the Iphlpapi.h header file. The Ipmib.h and Iprtrmib.h header files should never be used directly.

Examples

To view an example that retrieves the MIB_IPFORWARDTABLE structure and then prints out the MIB_IPFORWARDROW structure entries in this table, see the GetIpForwardTable function.

Requirements

Minimum supported client

Windows 2000 Professional [desktop apps only]

Minimum supported server

Windows 2000 Server [desktop apps only]

Header

Ipmib.h on Windows Server 2008 and Windows Vista (include Iphlpapi.h);
Iprtrmib.h on Windows Server 2003, Windows XP, and Windows 2000 (include Iphlpapi.h)

See also

CreateIpForwardEntry
DeleteIpForwardEntry
GetIpForwardTable
GetIpInterfaceEntry
MIB_IPFORWARDTABLE
MIB_IPINTERFACE_ROW
Protocol Identifiers
SetIpForwardEntry

 

 

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