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Discussion Starter · #1 ·
I have three PCs connected via Blackbox switch. They all run a program called Roam Alert which is security software for door alarms. We have the main server which has it's own static IP and then we have the other two machines using DHCP.

My problem is that the 2nd computer that we use is not communicating properly with Roam Alert. This started after we upgraded our PCs. On the first PC we were able to plug in the new one, add the work group and we were set. We went to the second one and got the communication issue. After much trial and tribulation we decided to put the old machine back on-line just so we would have it but now that one says it can't communicate either.

The weird thing is that the computers all see each other on the network. I can share files back and forth and also ping with no lost packets.

I do have all of my firewalls disabled as we don't need internet access on this network.

I do not have any virus software running. (I even removed it from the machine)

I've also tried releasing and renewing the IP address and also flushing the DNS.

The funny thing is, we tried putting the working computer on the 2nd ethernet port and we still had the same issue.

Does anyone have any ideas? I've been scratching my head for a week trying to get this up and running.

Thanks!
 

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Discussion Starter · #3 ·
Ok, the main server is
IP 169.254.242.90
Subnet is 255.255.0.0
Default Gateway is blank


#2
IP 169.254.36.142
Subnet 255.255.0.0
DG is blank

#3 (non working) is
IP 169.254.200.101
Subnet 255.255.0.0
DG is blank
 

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Hello,

None of computers has working ipconfig /all.
We have the main server which has it's own static IP and then we have the other two machines using DHCP.
What's the setup of your network? Where is DHCP coming from?
Mine is: Modem=> Router=> Computer - I have my DHCP coming from the router.
 

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Discussion Starter · #6 ·
Why are you using Apipa ips?

What is APIPA? - A Word Definition From the Webopedia Computer Dictionary

Dhcp does not normally hand out apipa ips but private ip usually in the 192.168.0 or1.x range.

Appears to me you need to properly configure your ip addresses.
Honestly we inherited this setup from the previous owners. They gave us no manuals or anything they just setup the PCs and left. So should I just switch everything over to static IP and assign them? We just have a switch with three PCs connected.
 

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Discussion Starter · #7 ·
Hello,

None of computers has working ipconfig /all.

What's the setup of your network? Where is DHCP coming from?
Mine is: Modem=> Router=> Computer - I have my DHCP coming from the router.
The main server has a static IP, the other two computers have DHCP. I don't know where it's coming from but until we tried replacing one of the PCs it worked fine. We have switch, computers. That's it. No internet access.
 

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Discussion Starter · #9 · (Edited)
I thought about replacing it with a Linksys router but since we didn't have internet access I didn't think it was necessary. We do have XP service pack 2 installed on the three machines.

Thanks for the help.
 

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Discussion Starter · #10 ·
Ok, just got back onsite and tried to set a static ip for the other pcs. I still dont know what fthe defauot gateway is i just left it blank (which is how its been from day 1).

I went to the second computer and used the same settings as the first but changed it to .100 that worked fine.

The trouble computer I did just as above but changed to .110 and no go. same as before.

I just noticed that we have a 1394- adapter installed to our door alarm that says connected. It also says dhcp installed. I have no info on this device as I said we inherited this system.

Does this help at all?
 

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You are connecting the door alarm via a firewire [1394] connection?
Usually you just disable that if not being used.

I would suggest you use the following ips

Unit1
192.168.1.1
255.255.255.0
no gateway or dns entries

Unit2
192.168.1.2
255.255.255.0
no gateway or dns entries

Unit3
192.168.1.3
255.255.255.0
no gateway or dns entries

On all three go into tcp/ip properties/wins tab and enable netbios over tcp/ip

Now if you go into entire network do you see all three listed?
 

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Okay... Let's review.

A) You have 3 PCs that all connect, and no need for Internet. This means you don't need a router or a defined default gateway,

B) The APIPA addresses usually mean the computers are enabled for DHCP, but aren't finding a DHCP server. This shouldn't matter, because the three computers all share a common subnet (169.254.x.x), which is why they can see each other and share files. It just isn't the 'normal' way to do it.

The 'normal' way would be to statically assign the IP addresses like so:

Computer A IP Address - 192.168.1.2
Computer B IP Address - 192.168.1.3
Computer C IP Address - 192.168.1.4
All with Subnet mask - 255.255.255.0 and no default gateway, although you could put in 192.168.1.1 if you'd like (this is what a router would default to if it was present).

But your door alarm device could cause an issue with this. If you could access it and statically assign it an address in the same subnet (192.168.1.100, for example) with the same subnet (255.255.255.0) you'd be fine. But it may be difficult to access, so you might want to leave things as they are...

So you call Computer #1 the 'Main Server'. My network is the same, although the 'Main Server' isn't really that at all... ;) What OS is it running? If it's a Windows Server OS, is the DHCP role enabled?

So you have two working PCs that properly communicate with the door alarm through the switch, and also communicate with the door alarm. You said the door alarm is a 1394-adapter, where does it plug into? The 'main server'? This next bit is also a little confusing...

The funny thing is, we tried putting the working computer on the 2nd ethernet port and we still had the same issue.
So, let's look at the switch and cabling for a moment. You have 3 PCs plugged into this switch. How many ports does the switch have? If you plug a working computer into the 2nd port and it ALWAYS fails with the same cable, but works when you plug it into one of the other ports, then it sounds like a port or cable issue. Eliminate the cable as the problem by swapping it with a working cable. If the issue follows the cable, then it's a bad cable. If the 2nd port still doesn't connect properly, then the port is somehow messed up.

One other thing you could try is just buying a Linksys 4 or 8-port switch (or a router, if you already have one, you'll just use the built-in 4-port switch in it) and swapping that in place of the Blackbox. That should eliminate the switch as being 'bad'.

Lastly, do you know how RoamAlert 'connects'? The fact the 'bad' PC can see and communicate with the others complicates things. 'Something' is interfering with that particular type of communication.
 

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Discussion Starter · #13 ·
Ok, I can't believe I did this but when I was on-site I had set the subnet mask on all the PCs to 255.255.0.0 and not 255.255.255.0. I'm going back there tomorrow so I'll check those things. I am also taking a wireless linksys router to swap the switch just in case.

Originally everything was working fine until they wanted to upgrade their towers. First replacement PC went in fine. Second one was when we started having problems with the Roam Alert software. We tried putting the old PC back online but the same problem existed.

I swapped ports on the switch with the known working PC and it worked fine so I don't think it's the switch. Even if I put the Linksys in I will still need to know the gateway right?

Thanks for all the help guys. I really appreciate it.
 

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Actually, your subnet mask for the APIPA addresses is correct. For example, if you take the IP addresses you listed, 169.254.242.90, 169.254.36.142 & 169.254.200.101, the subnet mask 255.255.255.0 will cut communication between them. since the '242', '36', and '101' parts of the address are now on different subnets. 255.255.0.0 will work, because then it's the same subnet. Again, it's just not the 'normal' way you would set it up, especially on an Internet-connected PC.

Again, the Default Gateway doesn't matter because you're not crossing subnets (ie., accessing teh InterWebs).

It's REALLY odd that the original '2nd PC' still didn't work when replaced. Especially since the 3rd new one did.
 
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