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!
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. > >
