[SANE-UG] Windows binding order

[Paul Howard]

Hi all

Been a while!

I've got a really tricky issue I cannot seem to resolve on a Windows 2008
server.

It's got 2 NICs installed and each has an IPv4 address configured.

So we have

NIC1 (192.168.1.1)
NIC2 (192.168.1.2)

Binding order is set to NIC 1 as first and all is good.

All of a sudden I will see the server unable to talk to other servers that
are configured to only allow traffic in from 192.168.1.1

And doing a pathping from this server shows it is using 192.168.1.2 as its
outgoing IP address

This lasts for a few mins and then it switches back to using 192.168.1.1

a few mins later it reverts again.

If I restart the server it will come online using 192.168.1.2 as the
default IP until I disable and re-enable both NICs

Anyone ever seen this before and have an idea of a resolution?

--
Paul Howard

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[Dave Phelan]

Paul,

Why are you using two NICs in the same subnet?
Can't you do NIC teaming and just have the one IP address?

Regards
Dave

--
Dave Phelan CCIE#3590 skype:davephelan GSM: 07990561784
dave....@gmail.com @daveph http://www.davephelan.org

"The best wifi is just that: free wifi throughout, no codes, no charges."
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[Paul Howard]

Hi Dave

It's a throwback to some older stuff that used to happen on the network.

Was done due to a lack of time and some developers that had hard coded some
addresses into some apps.

Unfortunately we need to keep things they way they are with the addresses
on 2 cards - which has always worked well up until this recent issue.

[Hazlitt Eastman]

Hi Paul,

So as Dave suggests, why not team the NICs and then bind both IP addresses to the NIC team.

Haze

[Paul Howard]

Hi Haze,

This was set because some of the websites hosted on that server are
accessed using a URL such as http://servername and those sites need to
be accessed using name only (as the sites are using host headers in IIS) -
if I was to bind all IPs to the same NIC all of the IPS would get
registered in DNS, which means sometimes when you call the server name you
will get a different IP address

The way the network has been set up means that we have a lot of aggressive
filtering on internal traffic so access to the internal sites has to be on
a certain IP - bit complicated to explain but necessary unfortunately. So
we can't change the way things work easily - I just have to work out why
windows keeps ignoring the binding order.



On Fri, Nov 11, 2016 at 12:07 PM, Hazlitt Eastman <haz...@manta9.com>
wrote:

> Hi Paul,
>
> So as Dave suggests, why not team the NICs and then bind both IP addresses
> to the NIC team.
>
> Haze
>

> On 11/11/2016, 12:05, "SANE-UG on behalf of Paul Howard" <sane-ug-bounces@

[Toby Leighton]

I haven't seen this exact issue of the binding flipping back and forth in
windows, but I have seen binding go funny for "no reason" (reason turned
out to be network driver updates)

https://technet.microsoft.com/en-us/library/cc732472(v=ws.10).aspx
(Protocol bindings and network order)

https://blogs.technet.microsoft.com/johnbaker/2009/09/23/how-do-i-get-rid-of-phantom-or-hidden-devices/

These may lead to clues as to what's going on, thing is on windows if you
have 2 NICs the friendly name might be adapter 1 and adapter 2, but in the
registry they might really be adapter 0 or adapter 11 or 12 and windows
doesn't make it immediately obvious what number they really are.

If both NICs are integrated on the motherboard of the server then I
wouldn't expect circumstances to switch them around, but if they are
different makes or one is a card then that could explain windows order
getting out of sync or forgetting/re adding one?
Can say either of those will be it, but could be the clue to get you
unstuck...

Toby

[Paul Howard]

Hi Toby

I have fixed t for now by changing the metric of each connection. Can't
fathom why Windows would see the pair of NICS as equal when I'm explicitly
choosing the binding order but hopefully this will keep things working
until I get time to investigate more.

Thanks for the replies everyone.