Maybe I'm being a little short sighted here, but the only option I can
think of is to create a script to detect and switch over when a dead
gateway is found, and then leave it running on a scheduled basis. Something
like this maybe:
$BkpDG = '192.168.1.2'
$AllDG = Get-NetIPConfiguration | select -exp $_.IPv4DefaultGateway.NextHop
ForEach ($DG in $AllDG) {
If (!(Test-NetConnection -ComputerName $DG -Quiet)) {
Get-NetIPConfiguration | New-NetIPAddress -DefaultGateway $BkpDG
}
}
PS: the code was put together in a hurry therefore was not tested.
On Fri, Jun 24, 2016 at 1:30 PM, Michael Leone <[email protected]> wrote:
> On Fri, Jun 24, 2016 at 12:04 PM, Rubens Almeida <[email protected]>
> wrote:
>
>> Here's my 2 cents on this matter: I'm still waiting to see when a Windows
>> server host will handle 2 gateways without trouble. I'm used to see on
>> every customer I'm assigned to work as SME on my day job. Every one of them
>> have this kind of issue on one degree or another. What I do is: on the
>> production NIC I set the customer's gateway. On all other NICs no gateway
>> at all. If needed, I then set a persistent routes pointing to the
>> respective gateway handling that specific network. Hope that helps!
>>
>
> As I said, there are no other NICs. Also, in case of disaster, I don't
> want to have to edit 175 VMs, to set addressing on a previously unused NIC
> (script-based or not). I need an automatic dead-gateway detection and
> failover, apparently.
>
>
>
>> Rubens
>>
>> On Fri, Jun 24, 2016 at 12:23 PM, Michael Leone <[email protected]>
>> wrote:
>>
>>> Here's my setup: I have a lot of VMware VMs. We also use their SRM (Site
>>> Recovery Manager) for Disaster Recovery. Basically, SRM lets the VMs fail
>>> over to another site, in case of disaster. They will keep their current IP
>>> addressing.
>>>
>>> So what we did was set 2 gateways on each VM - first entry is x.x.x.1,
>>> which is the gateway at the production site. Second entry is x.x.x.2, which
>>> is the gateway at the recovery site. This way, if the VMs did fail over,
>>> they would still be able to find a gateway and continue to work (since
>>> theoretically x.x.x.1 would not be available, being a smoldering pile of
>>> ash or whatever). Note that these are all 1 NIC machines, no multi-homing.
>>> And all static addressing, no DHCP.
>>>
>>> I seem to recall testing this a couple years ago, and it worked fine.
>>> However, I'm old, so who knows how faulty my memory is ...
>>>
>>> Here's the problem - yesterday the recovery site went down. Mind you,
>>> the main production site stayed up, and in fact, has never gone down. But
>>> then I started getting weird calls - I couldn't ping some VMs, yet other on
>>> the same subnet as I am had no difficulties.
>>>
>>> Eventually, what I had to do was delete the x.x.x.2 gateway entry from
>>> the problematical machines, flush their DNS cache, and then everyone could
>>> access these VMs again.
>>>
>>> But why?. Since the main production site switch never went down, none of
>>> the VMs should have been using the recovery site as a gateway; they should
>>> all have been using x.x.x.1, and the fact that x.x.x.2 was unavailable
>>> should not have matter to them in the slightest.
>>>
>>> And even if they were using the recovery site x.x.x.2 as gateway, once
>>> it dropped, the VM should have still been able to use the other entry, the
>>> production site switch x.x.x.1, as a gateway and continued to be available.
>>>
>>> So, 3 questions then:
>>>
>>> 1. Am I wrong in believing that a Windows machine (Win 2008 R2 and Win
>>> 2012 R2) will use the gateways in the order listed? (i.e., use x.x.x.1
>>> first, and not try to use x.x.x.2 unless x.x.x.1 is unavailable). Seems
>>> most of my VMs worked this way, but not all, yet all are configured the
>>> same way.
>>>
>>> 2. And, if the gateway in use (for example, x.x.x.2) becomes
>>> unavailable, I thought Windows would automatically try the other entry,
>>> without any user intervention. Is this not so?
>>>
>>> 3. What I want is that for the VMs to use the first gateway listed. If
>>> it can't reach or use that, then I want it to automatically use the next
>>> entry in the gateway list. Is this possible? If so, then how?
>>>
>>> Thanks for any help.
>>>
>>>
>>
>
