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Should be a simple question, just a little bit outside my normal scope (I'm a system builder, not a network engineer).

I'm trying to fix a network slowdown issue at a 6 PC office. They have a normal home router in a back room with wifi and two wired systems attached to it. Two wifi PCs at the front desk also run MYOB which apparently uses every piece of network bandwidth possible and goes REALLY slow (Minutes instead of seconds to process something). I've been told that because they use so much bandwidth it should always be on a wired connection.

Now here's the problem, because of the layout I can't run cables out to the front desk (Already been denied by management to stick cables in the walls). The solution is going to be to stick a small 4 port switch in between the two PCs and connect them directly with static IPs.

So the question is going to be, how do I set this up so that any local traffic between those two PCs for MYOB runs over the cable and still give both of them access to the wifi for the Internet and printers? Is Windows smart enough to route the fastest way? I already know about making sure they're on different subnets than the DHCP network on the router and to not have a default gateway on the internal network, but beyond that I don't know if Windows will pick the right NIC.

Edit: It should look roughly like the map in case two here: http://www.ni.com/white-paper/12558/en/#toc3 Just instead of being the same PC it's two PCs connected with a switch and the external network they connect to is over wifi.

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  • if you are going to connect two computers directly, why not use a crossover and skip the switch out entirely
    – gwillie
    Aug 10, 2015 at 3:57
  • Already had the hardware for it. And if I ever get the opportunity to route one cable out the front then I can just use it to daisy chain. The theory of a switch and a crossover should still be the same though.
    – LastElf
    Aug 10, 2015 at 4:03
  • We have MYOB here too, when I first installed new version with flash GUI, it was a slug, so upgraded accountants com, quad core 16gb ram ssd 1GB nic etc. I moved the db files locally (which sounds like you won't be able to do), the accountant still has to wait for operations to complete but so not as bad as it was (IMO myob slows it's internal operations down to minimize on corruption, because it takes a lot longer nowaday to do anything). Have you tested for link saturation, how do you know it's maxing bandwidth? Have you moved the db files locally to see what happens.
    – gwillie
    Aug 10, 2015 at 4:37
  • There's two PCs with the same specs (I think i5's? They're fairly recent SFF boxes) running AccountRight 19. The company file is stored on one of the PCs and that does things in seconds. The other PC when it loads the file over the wifi takes minutes to do the same thing. Originally I was thinking it was just related to the PC it was hosted on and so move the file to one of the PCs that's on a wired NIC. Apparently that didn't help the situation any though which is why I'm thinking it's a wifi issue over a disk/ram issue.
    – LastElf
    Aug 10, 2015 at 4:46
  • It could be the db engine that MYOB is using on local computer. IMO I can't see these db operations being that slow on wireless, maybe interfence: lots of other wifi networks in 2.4 or 5 ghz...interference with other electronics, fridge nuc, elevator etc. Give MYOB a call, I reckon they've heard this before. And my last point, DON'T USE WIFI WITH SENSITIVE DATA. MANAGEMENT IN THAT COMPNAY NEEDS TO BE EXPLAINED HOW EASILY IT IS TO CRACK WPA by a 10 year old kid with a $100 laptop and $50 wifi jammer and 24 hours reading on the internet. Get them to use wired
    – gwillie
    Aug 10, 2015 at 5:30

1 Answer 1

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Both computers will have two NICs and two IP addresses. They will be the only computers on the "accounting" network which will have its own subnet. The two subnets must not overlap.

The way to ensure that the traffic between the computers uses the accounting network is to use name resolution in conjuction with the inbuilt routing table in each computer. As long as each computer 'understands' that the resource that it is trying to get at is on the accoounting subnet it will use the accounting NIC to get at it. Replies to the traffic from the other PC are critical too and need the same consideration. However, they will not automatically work this out.

PCs use name resolution to decide what the IP address of the resource they are after is. You will setup MYOB to request a name like "PC1" and name resolution will decide what is the right IP for PC1. Then you will try to send traffic to the IP.

There are various ways to resolve names and normally in a small office there is an internal or external DNS server. An external DNS sserver will return nothing useful and an internal one may well return the 'normal' IP of the other PC.

You can override the normal DNS process by using a host file on each PC. In Windows this is a system file that is in %systemroot%\system32\drivers\etc\ (see this article). Sometimes the folder is hidden but it is there.

You can either direct all traffic between the PCs to use the accounting network by placing an entry for PC1 on PC2 using the accounting IP for PC1 (and vice versa) or you can add a dummy name like "PC1-accounting" with the appropriate IP and use this name when you set up MYOB.

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  • Spot on. Different subnets, hosts file set up. Aug 10, 2015 at 8:45
  • So just put a reference to the PC name in the hosts file and then all traffic directed at that name will route over the IP I pick? Sounds easy as. Usually I just use the file to block domains so it's nice to use it for its real purpose for once. Thanks a lot!
    – LastElf
    Aug 10, 2015 at 8:45

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