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31 Messages
Computers with static and dynamic ips cannot see each other.
We have a comcast account with 5 static IPs. Our network has about 15 computers, so 5 of them have a static IP and the rest use dynamic IPs (private IP such as 10.1.10.100, ...). At first, everything works fine. Our Web server (static IP) can send print jobs to our printer (private IP), and networks shares on the servers (static IP) can be accessed by everybody (either static or dynamic IP). But recently, computers from one IP group will not be able to connect to computers from the other group. Servers cannot send print jobs to printer, users cannot connect to shares, ... Anybody has any suggestion what go wrong and how we can fix it? Thanks.
CCMichael
Gold Problem solver
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575 Messages
8 years ago
Hello quetek and welcome to forums,
After reading over your post the first though is that one of your devices sharing the networks signal might not be routing correctly. Have you reset all of your network equipment while trying to isolate this problem?
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quetek
New problem solver
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31 Messages
8 years ago
Our network is very simple. All computers are connected to a hub. Then the hub is connected to the comcast modem/router. The default Gateways for both private and static networks are on this very same modem. At first everything worked. And now no longer works. We have power cycle the modem, asked comcast to reset the modem remotely, .... didn't help.
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CCMichael
Gold Problem solver
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575 Messages
8 years ago
Thank you quetek,
Have you checked the IP address and subnet masking on all the systems to ensure they are similar (i.e. 192.168.0.xxx 255.255.255.0). Also have you tried swapping the ports that the devices are plugged into to see if this helps?
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quetek
New problem solver
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31 Messages
8 years ago
Basically, there are two networks
one uses private IPs (10.1.10.X, mask 255.255.255.0, gateway 10.1.10.1),
the other uses static IPs (50.254.___.X, mask 255.255.255.248, gateway 50.254.___.62).
The gateways are on the same modem/router.
The problem: A machine can talk to other machine on the same network, but not to machine on another network.
For example:
10.1.10.10 can ping 10.1.10.11,
10.1.10.10 can *not* ping 50.254.___.60.
However,
10.1.10.10 can ping 50.254.___.62 (the gateway of the other network).
So we believe setting in the modem/router decides that "No, I won't route your packets to the other network".
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__J__
New problem solver
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14 Messages
8 years ago
Just a guess, but... if you asked your modem/router why it's not routing like you want, it would probably say "because I can't do hairpinning".
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quetek
New problem solver
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31 Messages
8 years ago
I didn't know about hairpinning, so learning a new concept here. Thanks.
This seems to be cheap modem so it's probably can't do hairpinning. But how come everything worked fine when we first switched service to comcast.
Furthermore, we used to have AT&T with the exact same configuration and never had any problem. Actually, the AT&T modem Web configuration tool have a whole page for setting up the private and static IPs. We could not find any like that for the comcast modem.
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skymeat
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39 Messages
8 years ago
You are using the Comcast modem as the default gateway. It's likely at 10.1.10.1/24.
So...All of the computers need to be on the 10.1.10.0/24 network.
The Comcast modem needs to static nat your public IP address to the 10.1.10.0/24 network.
Then all of the computers are on the same network internally, and incoming requests from the internet know where to go.
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