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Limited Network Connectivity for some workstations

Posted on 2010-09-23
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Last Modified: 2012-06-27
Hi there,

I'm seeing a something new and unusual for me today.  Cable connection to a Linksys router, some workstations connecting via wifi, others via ethernet.  But some computers are experiencing intermittent connections.  They're still showing a strong wireless connection to the network, but no connectivity.

Example: right now I have 3 computers in front of me.  This one is fine (IP 192.168.1.106).  But the other two are showing strange IPs: 192.168,0,125, while the router says it's assigning 192.168.1.100 to 1.149.  Where did this .0.125 come from, and is that why this laptop is showing no connectivity to internet or other machines?  (Can't ping it, can't ping from it.)

Any help would be greatly appreciated!
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Question by:Kenten
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by:haseebsaleem
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instead of using "Obtain IP address automatically" you should assign the IP address in "Use the following IP address"
 
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by:fs40490
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It could be that the other two are connecting to a different access point.  One the Access Point do you see the MAC addresses of the machines having the issues?  If you do then I would try what haseebsaleem stated, assigning a static IP in the proper range for use on the wireless connection.
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by:SysExpert
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ALso check the alternate IP settings. Make sure it is set for DHCP and not fixed.

I hope this helps !
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by:Kenten
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Thanks for the help so far!

The router is set to DHCP.

I see my MAC address in the router's DHCP Client Table and my computer name, but the ip address listed there (192.168.1.101) doesn't match the one my computer give with ipconfig (192.168.0.125).  Previously, my computer had no problem joining this network, now we're all having intermittent problems.

Side question: If I change my laptop to static IP, won't it try to always use that IP for any network I'm on, even my home network?  And if I set my laptop to a static IP, which one do I use: the 1.101 of the router, or 0.125 of my ipconfig, or something new?

Right now, any computer with a different IP than the one the router says it has, has zero connectivity even though each computer says it's connected to the network...  Any thoughts?
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by:Kenten
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If there's any data from ipconfig /all or from the router that I could give you, let me know.

By the way, ipconfig says my default gateway is 192.168.0.1?  This linksys router is 192.168.1.1, is this a cause or symptom, or irrelevant?

I reset the router once today to no avail.  And if I connect a laptop via ethernet to the hub (which the linksys feeds internet to), then we have a good connection.  I don't know if that helps you.  Maybe the linksys router (5 months old) is crapping out?
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fs40490 earned 125 total points
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you should give the laptop an IP address that is within the network range that the 1.1 interface is on and try that.

Yes a static IP would always override the DHCP and would only work while at work (unless your other network uses the same private IP space.

What IP does a computer that has the 0.xxx say the DHCP server is?

It really sounds like another computer is acting as a dhcp server and interferring with your configuration.
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by:Kenten
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In the Linksys router configuration, I used DHCP reservation to give a certain IP to my laptop.  Disconnected/reconnected my laptop, no effect.  My laptop still has the unusual ip of 192.168.0.125 (which I've never seen before).

It sounds like the staff here has been frequently unplugging the router whenever they lost connectivity, which might be a relevant detail?
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by:fs40490
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Are you running windows?  If so can you run ipconfig /all from a command prompt and post the information here.
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by:Kenten
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Hi fs40490,

It says the DHCP server is 192.168.1.98.  I think that's the static IP of the file server...!

Hmm, that's not right.  I'll go disconnect the file server and see if that solves it...  Why is my laptop asking the file server for an ip address?
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by:fs40490
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The is actually not how it works...  The computer broadcasts to see if there is a DHCP server available to give it an IP.  Your fileserver probably had someone configuring services and someone accidentally DHCP.

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by:Kenten
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Disconnecting the file server restored connectivity!  Thanks fs40490!

Now, I still need the file server.  Should I assign a different IP?  (I'm typing this on a mac, but I'll shuffly over to the XP machine...
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by:fs40490
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Have everyone do an ipconfig /release and ipconfig /renew.  Once everyone completes that you should be able to put the fileserver back on line.

Then take a look at the fileserver and see if it has a DHCP server configured on it.  If so just disable it, or uninstall that component and you should be good.

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by:Kenten
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So I can wade through the CentOS file server and find a way to turn off DHCP?  I can figure that out, I'm sure.

Here's my ipconfig, if you still think it's relevant:

Windows IP Configuration

        Host Name . . . . . . . . . . . . : Cobra
        Primary Dns Suffix  . . . . . . . : admins-Computer.local
        Node Type . . . . . . . . . . . . : Broadcast
        IP Routing Enabled. . . . . . . . : No
        WINS Proxy Enabled. . . . . . . . : No
        DNS Suffix Search List. . . . . . : admins-Computer.local
                                            vc.shawcable.net

Ethernet adapter Wireless Network Connection:

        Connection-specific DNS Suffix  . : vc.shawcable.net
        Description . . . . . . . . . . . : Atheros AR5007EG Wireless Network Ad
apter
        Physical Address. . . . . . . . . : 00-23-4E-39-00-3B
        Dhcp Enabled. . . . . . . . . . . : Yes
        Autoconfiguration Enabled . . . . : Yes
        IP Address. . . . . . . . . . . . : 192.168.1.103
        Subnet Mask . . . . . . . . . . . : 255.255.255.0
        Default Gateway . . . . . . . . . : 192.168.1.1
        DHCP Server . . . . . . . . . . . : 192.168.1.1
        DNS Servers . . . . . . . . . . . : 64.59.144.90
                                            64.59.144.91
                                            64.59.150.134
        Lease Obtained. . . . . . . . . . : September 23, 2010 1:23:30 PM
        Lease Expires . . . . . . . . . . : September 24, 2010 1:23:30 PM

Ethernet adapter Local Area Connection:

        Media State . . . . . . . . . . . : Media disconnected
        Description . . . . . . . . . . . : Realtek RTL8102E Family PCI-E Fast E
thernet NIC
        Physical Address. . . . . . . . . : 00-23-8B-23-F3-9A
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Author Comment

by:Kenten
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Hmm, by posting that, I didn't just open up my worknetwork to exploitation, did I?  <:/
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by:fs40490
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No because nothing really shows anyone where you are actually at, just gives information about your provider, but you are right that you should take care in what you post, however you are fine with this one.
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Author Closing Comment

by:Kenten
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File server was acting as a DHCP server and interfering with the router.  Disabling DHCP on the file server solved the problem.
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