0

I have created a Windows loop back adapter with 'Obtain IP address Automatically' enabled. 

ipconfig /all

Ethernet adapter LL Address:

   Connection-specific DNS Suffix  . :
   Description . . . . . . . . . . . : Microsoft Loopback Adapter #3
   Physical Address. . . . . . . . . : XX-XX-XX-XX-XX-XX
   DHCP Enabled. . . . . . . . . . . : Yes
   Autoconfiguration Enabled . . . . : Yes
   Autoconfiguration IPv4 Address. . : 169.254.8.151(Preferred)
   Subnet Mask . . . . . . . . . . . : 255.255.0.0
   Default Gateway . . . . . . . . . :
   NetBIOS over Tcpip. . . . . . . . : Enabled

So I believe the adapter has taken a Link Local address. Now we have an embedded networking device in which I hard code the same Link Local address to test AUTO IP Link Local address functionality. This embedded code is developed using VC - so we can compile and run on same host where I have setup the Loopback adapter.

After bringing on the embedded networking code I see ARP request going out stating 'Who has 169.254.8.151' but I see no reply back from Loopback adapter that the IP is at XX-XX-XX-XX Hardware?

Should not the Loopback adapter reply back stating the same? What wrong or extra needs to be done to make this Loopback adapter reply back stating the same?

Improve this question
1
  • Is the application using the loopback adapter, or only the physical adapter? Which adapter's traffic are you monitoring?
    – Harry Johnston
    Jun 30, 2018 at 5:31

2 Answers 2

Reset to default
0

Should not the Loopback adapter reply back stating the same?

No. The loopback adapter is a software construct. It is entirely internal to the host.

Improve this answer
2
  • But both of them are running on same host - is there a way I can put both on same logical network?
    – Programmer
    Jun 29, 2018 at 16:02
  • Updated the question that both embedded software and loopback adapter are on same hosts
    – Programmer
    Jun 29, 2018 at 16:10
0

If you want to reach a loopback address over a network, then you need to have another IP address configured on a real interface, which is operational. In addition to this you need to advertise your loopback address into the routing domain (eg. ospf or bgp). The packets will be routed through your real interface and land on your loopback interface's virtual nic.

Improve this answer
1
  • Now I see 2 ARP probes - one to certify that the another IP and Link Local IP advertising who owns it and not the address conflict. Please explain "loopback address into the routing domain (eg. ospf or bgp). " - what needs to be configured in the loopback adapter?
    – Programmer
    Jun 29, 2018 at 17:52

You must log in to answer this question.

Not the answer you're looking for? Browse other questions tagged .