virtual ip on loopback adapter with netsh

This problem is relating to Windows 2003 SP 2. I've been trying to figure
out why we have routing problems with a loopback adapter that has a vip for
load balancing iis. The box in question has two nics, one to internet and
another to the backbone in conjunction with the loopback adapter which goes
to the backbone (we have to balance on the backbone too).

Here's the route print:


IPv4 Route Table
================================================== =========================
Interface List
0x1 ........................... MS TCP Loopback interface
0x2 ...02 00 4c 4f 4f 50 ...... Microsoft Loopback Adapter
0x10004 ...00 1e 0b 74 d8 3c ...... HP NC373i Multifunction Gigabit Server
Adapter #2
0x10005 ...00 1e 0b 74 d8 3e ...... HP NC373i Multifunction Gigabit Server
Adapter
================================================== =========================
================================================== =========================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 207.18.55.1 207.18.55.204 20
10.0.0.0 255.0.0.0 10.15.1.250 10.15.1.225 1
10.15.1.0 255.255.255.0 10.15.1.116 10.15.1.116 10
10.15.1.0 255.255.255.0 10.15.1.225 10.15.1.225 30
10.15.1.116 255.255.255.255 127.0.0.1 127.0.0.1 10
10.15.1.225 255.255.255.255 127.0.0.1 127.0.0.1 30
10.255.255.255 255.255.255.255 10.15.1.116 10.15.1.116 10
10.255.255.255 255.255.255.255 10.15.1.225 10.15.1.225 30
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
207.18.55.0 255.255.255.0 207.18.55.204 207.18.55.204 20
207.18.55.204 255.255.255.255 127.0.0.1 127.0.0.1 20
207.18.55.255 255.255.255.255 207.18.55.204 207.18.55.204 20
224.0.0.0 240.0.0.0 10.15.1.116 10.15.1.116 10
224.0.0.0 240.0.0.0 10.15.1.225 10.15.1.225 30
224.0.0.0 240.0.0.0 207.18.55.204 207.18.55.204 20
255.255.255.255 255.255.255.255 10.15.1.116 10.15.1.116 1
255.255.255.255 255.255.255.255 10.15.1.225 10.15.1.225 1
255.255.255.255 255.255.255.255 207.18.55.204 207.18.55.204 1
Default Gateway: 207.18.55.1
================================================== =========================
Persistent Routes:
Network Address Netmask Gateway Address Metric
10.0.0.0 255.0.0.0 10.15.1.250 1


Here's when it's working:


IPv4 Route Table
================================================== =========================
Interface List
0x1 ........................... MS TCP Loopback interface
0x10004 ...00 1e 0b 74 d8 3c ...... HP NC373i Multifunction Gigabit Server
Adapter #2
0x10005 ...00 1e 0b 74 d8 3e ...... HP NC373i Multifunction Gigabit Server
Adapter
0x70002 ...02 00 4c 4f 4f 50 ...... Microsoft Loopback Adapter
================================================== =========================
================================================== =========================
Active Routes:
Network Destination Netmask Gateway Interface Metric
0.0.0.0 0.0.0.0 207.18.55.1 207.18.55.204 20
10.0.0.0 255.0.0.0 10.15.1.250 10.15.1.116 1
10.15.1.0 255.255.255.0 10.15.1.116 10.15.1.116 10
10.15.1.0 255.255.255.0 10.15.1.225 10.15.1.225 30
10.15.1.116 255.255.255.255 127.0.0.1 127.0.0.1 10
10.15.1.225 255.255.255.255 127.0.0.1 127.0.0.1 30
10.255.255.255 255.255.255.255 10.15.1.116 10.15.1.116 10
10.255.255.255 255.255.255.255 10.15.1.225 10.15.1.225 30
127.0.0.0 255.0.0.0 127.0.0.1 127.0.0.1 1
207.18.55.0 255.255.255.0 207.18.55.204 207.18.55.204 20
207.18.55.204 255.255.255.255 127.0.0.1 127.0.0.1 20
207.18.55.255 255.255.255.255 207.18.55.204 207.18.55.204 20
224.0.0.0 240.0.0.0 10.15.1.116 10.15.1.116 10
224.0.0.0 240.0.0.0 10.15.1.225 10.15.1.225 30
224.0.0.0 240.0.0.0 207.18.55.204 207.18.55.204 20
255.255.255.255 255.255.255.255 10.15.1.116 10.15.1.116 1
255.255.255.255 255.255.255.255 10.15.1.225 10.15.1.225 1
255.255.255.255 255.255.255.255 207.18.55.204 207.18.55.204 1
Default Gateway: 207.18.55.1
================================================== =========================
Persistent Routes:
Network Address Netmask Gateway Address Metric
10.0.0.0 255.0.0.0 10.15.1.250 1

We found that if we disable the loopback, reboot, enable the loopback we're
able to get to the machine from another machine on the backbone and the
internet connection works fine. So, as a workaround to getting the route
table figured out, we try to do a devcon disable *Loop on shutdown script. I
can run this all day from a command prompt, but whenever we runs in in the
shutdown script, it doesn't work. netsh also works fine. But again when run
from a shutdown script it returns "Loopback" not found.

Also, I notice that when I disable the loopback, set it to dhcp and then do
a route print the persistent route of 10.0.0.0 disappears. When I re-enable
the loopback, set the ip to it, re-add the 10.0.0.0 route, everything starts
working again.

Hi,
when it is at night the same cold as outside, i will find the inverted bit
jk

I've found some more out. So with the above routes, we can see that the
loopback is stepping on the backbone nic route as it appears to start last:

Active Routes:
Network Destination Netmask Gateway Interface Metric
10.0.0.0 255.0.0.0 10.15.1.250 10.15.1.225 1
10.15.1.0 255.255.255.0 10.15.1.116 10.15.1.116 10

To fix the problem, I do a route add 10.0.0.0 mask 255.0.0.0, this puts the
backbone nic to the top:

Active Routes:
Network Destination Netmask Gateway Interface Metric
10.0.0.0 255.0.0.0 10.15.1.250 10.15.1.225 1
10.15.1.0 255.255.255.0 10.15.1.116 10.15.1.116 10


Now the million dollar question is, how can we get the loopback adapter to
"start" last?

I'm having a very similar issue.

I route out to a different network and when the loopback adapter is
enabled I'm unable to ping the network. If I disable and re-enable the
loopback, I can ping the network for EXACTLY 10 min.

I tried messing around with the metrics on the interfaces but none of
this seems to make any difference...


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Brucifer
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I thought I could do the route add / delete thing too. What a mess it
created.

We disable loopback, reboot, enable loopback and we're ok until the next MS
patches come out. Kind of painful to do this every time, but seems to be the
only option. Something is definitely broke.