Different Adapter Lists Returned
I would like to know the root cause of why GetIpAddrTable would return fewer network adapters than GetAdaptersAddresses. Candidate reasons are given below (updated per answers).
Candidate Reasons
- IPv6 adapters: These will only show up for
GetAdaptersAddresses. In this example I have a case of an adapter with link-local IP addresses for both IPv4 and IPv6 that does not show up in output from GetIpAddrTable.
Background
I’m investigating a problem with the GetIpAddrTable function on a specific Dell laptop running Windows 7 64-bit Home Premium (version: 6.1.7601 Service Pack 1 Build 7601). The system in question is unable to detect certain network adapters via GetIpAddrTable. Diagnostic results are given below.
Can anyone explain why I might see such wildly different results from these two functions? We’ve been using GetIpAddrTable for close to two years without any problems.
Documentation Check
The documentation for GetIpAddrTable indicates that link state detection may cause problems for XP, but it does not give any reasons why adapters would not show up at all. It appears that virtual adapters are not included, but our device is not a virtual adapter (it is Ethernet over USB).
On Windows Server 2008 and Windows Vista, the IPv4 addresses returned
by the GetIpAddrTable function are not affected by the media sensing
capability of the TCP/IP stack on a local computer. The GetIpAddrTable
function returns only valid IPv4 addresses.
In the testing I’ve conducted on this system we have a valid connection, but it is only reported by GetAdaptersAddresses, not GetIpAddrTable. I suspect that Windows thinks the adapter is not valid, but I’m not sure what to test to confirm this theory. Packets are flowing to and from the device, it just isn’t visible in the IPv4 address mapping table.
Implementation Details
- We use the Belcarra USBLAN ethernet gadget driver (customized for our company)
- We expect our device to register via DHCP for the host and device
- The driver provides DHCP
- Our first host adapter is given 169.254.142.9
- Our first device adapter is given 169.254.142.10
- Traffic to our device is not routed externally (link-local)
GetIpAddrTable Results
Normally we would expect to see two or three network adapters and never the loopback adapter. Perhaps the presence of 127.0.0.1 in this list is part of the problem – it isn’t normally observed on a working machine.
- Adapter 1: Software Loopback Interface 1
- Adapter 2: Intel(R) Centrino(R) Wireless-N 1030
GetAdaptersAddresses Results
I’ve listed the adapters returned by this function in the order that they were returned. Matching adapters from the first call are emphasized. The only adapter not present in ipconfig output is in bold.
- Adapter 1: USBLAN Adapter
- Adapter 2: Microsoft Virtual WiFi Miniport Adapter
- Adapter 3: Bluetooth Device (Personal Area Network)
- Adapter 4: Intel(R) Centrino(R) Wireless-N 1030
- Adapter 5: Realtek PCIe GBE Family Controller
- Adapter 6: Software Loopback Interface 1
- Adapter 7: Microsoft ISATAP Adapter
- Adapter 8: Microsoft ISATAP Adapter #2
- Adapter 9: Teredo Tunneling Pseudo-Interface
- Adapter 10: Microsoft ISATAP Adapter #3
- Adapter 11: Microsoft ISATAP Adapter #4
- Adapter 12: Microsoft ISATAP Adapter #5
ipconfig /all Results
Notice that the software loopback adapter is the only one not present – which indicates that ipconfig is using the second function or a similar interface internally.
- Adapter 1: USBLAN Adapter
- Adapter 2: Microsoft Virtual WiFi Miniport Adapter
- Adapter 3: Bluetooth Device (Personal Area Network)
- Adapter 4: Intel(R) Centrino(R) Wireless-N 1030
- Adapter 5: Realtek PCIe GBE Family Controller
- Adapter 6: Microsoft ISATAP Adapter
- Adapter 7: Microsoft ISATAP Adapter #2
- Adapter 8: Teredo Tunneling Pseudo-Interface
- Adapter 9: Microsoft ISATAP Adapter #3
- Adapter 10: Microsoft ISATAP Adapter #4
- Adapter 11: Microsoft ISATAP Adapter #5
Cross-Referencing Results
It appears that the ipconfig /all command is returning the same data as GetAdaptersAddresses with the exception of the software loopback interface. I am currently looking at switching our library to use GetAdaptersAddresses in order to plug this issue, but I’m concerned about why GetIpAddrTable is not returning expected results. Thanks in advance for any input!
GetIpAddrTable()only returns IPv4 interfaces.GetAdaptersAddresses()returns IPv4 and/or IPv6 adapters, and single adapter can have multiple IP addresses assigned to it.You are comparing apples and oranges, and wondering why you have fewer apples than oranges.