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Network slows, loses Internet connectivity at the same time every week

Posted on 2007-10-11
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Once a week, at the same time every week (between 11:00 a.m. and 1:00 p.m.), our local area network pretty much loses all connectivity to the Internet, and interaction among the computers on the LAN slows way down. We are about 20 Windows XP computers on a Windows Small Business Server 2003 network.

It sounds suspiciously like a backup process, or virus scan, or something like that running on a once-a-week schedule -- but the network administrator (an outside firm) says no. Can servers be set up to re-lease IPs once a week? Would that cause such a thing.
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Question by:Dbast
12 Comments
 
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Expert Comment

by:zcrammond
ID: 20059592
well in theory yes, you can schedule servers to refresh drop or edit their IP's but really, best practise is to never do such a thing within the working times.

is there nothing in the event viewer of the servers which shows abnormal messages, warning or even errors during these times?

I find it hard to believe that the downtime can happen without any outward sign of what is going on, if it is happening, someone has purposfully made it happen!


I would check the event logs, they will probably go back a few weeks so you can easily compare this weeks with last weeks etc.

how closely has your network admin looked at the problem?
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bluetab earned 1500 total points
ID: 20061463
One of the biggest causes of a network "slowdown" is the tranferring of large files across the LAN or over the Internet.  You may want to check your servers to see if a backup is not running at that time or that users are not downloading files.  

The best way to find the issue is to put a network sniffer out there before the slowdown occurs.  Ethereal has a free download that will let you do some basic sniffing to see what machine(s) is causing the problem.
http://www.ethereal.com/
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Expert Comment

by:Jeffrey Kane - TechSoEasy
ID: 20064667
It actually sounds like a misconfigured DHCP server.  But can you  please post a COMPLETE ipconfig /all from both the SBS as well as a sample workstation?

Jeff
TechSoEasy
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Author Comment

by:Dbast
ID: 20065587
Here is the SBS ipconfig /all



Windows IP Configuration



   Host Name . . . . . . . . . . . . : hidc

   Primary Dns Suffix  . . . . . . . : heartland.local

   Node Type . . . . . . . . . . . . : Unknown

   IP Routing Enabled. . . . . . . . : Yes

   WINS Proxy Enabled. . . . . . . . : Yes

   DNS Suffix Search List. . . . . . : heartland.local



PPP adapter RAS Server (Dial In) Interface:



   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : WAN (PPP/SLIP) Interface

   Physical Address. . . . . . . . . : 00-53-45-00-00-00

   DHCP Enabled. . . . . . . . . . . : No

   IP Address. . . . . . . . . . . . : 192.168.0.121

   Subnet Mask . . . . . . . . . . . : 255.255.255.255

   Default Gateway . . . . . . . . . :

   NetBIOS over Tcpip. . . . . . . . : Disabled



Ethernet adapter Server Local Area Connection:



   Connection-specific DNS Suffix  . :

   Description . . . . . . . . . . . : Broadcom NetXtreme Gigabit Ethernet

   Physical Address. . . . . . . . . : 00-18-8B-E6-1F-DA

   DHCP Enabled. . . . . . . . . . . : No

   IP Address. . . . . . . . . . . . : 192.168.1.200

   Subnet Mask . . . . . . . . . . . : 255.255.255.0

   IP Address. . . . . . . . . . . . : 192.168.0.10

   Subnet Mask . . . . . . . . . . . : 255.255.255.0

   IP Address. . . . . . . . . . . . : 192.168.0.2

   Subnet Mask . . . . . . . . . . . : 255.255.255.0

   Default Gateway . . . . . . . . . : 192.168.0.1

   DNS Servers . . . . . . . . . . . : 192.168.0.2

   Primary WINS Server . . . . . . . : 192.168.0.2



Here is the ipconfig /all from one of the local machines:



Windows IP Configuration



        Host Name . . . . . . . . . . . . : dbast

        Primary Dns Suffix  . . . . . . . : heartland.local

        Node Type . . . . . . . . . . . . : Unknown

        IP Routing Enabled. . . . . . . . : Yes

        WINS Proxy Enabled. . . . . . . . : Yes

        DNS Suffix Search List. . . . . . : heartland.local

                                            heartland.local



Ethernet adapter Local Area Connection:



        Connection-specific DNS Suffix  . : heartland.local

        Description . . . . . . . . . . . : Intel(R) PRO/100 VE Network Connection

        Physical Address. . . . . . . . . : 00-13-20-7C-89-16

        Dhcp Enabled. . . . . . . . . . . : Yes

        Autoconfiguration Enabled . . . . : Yes

        IP Address. . . . . . . . . . . . : 192.168.0.105

        Subnet Mask . . . . . . . . . . . : 255.255.255.0

        Default Gateway . . . . . . . . . : 192.168.0.1

        DHCP Server . . . . . . . . . . . : 192.168.0.2

        DNS Servers . . . . . . . . . . . : 192.168.0.2

        Lease Obtained. . . . . . . . . . : Friday, October 12, 2007 8:14:23 AM

        Lease Expires . . . . . . . . . . : Saturday, October 20, 2007 8:14:23 AM

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Expert Comment

by:Jeffrey Kane - TechSoEasy
ID: 20065665
Why do you have those two other IP addresses on the NIC?  (Especially the one with a different IP Subnet?)

Jeff
TechSoEasy
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LVL 74

Expert Comment

by:Jeffrey Kane - TechSoEasy
ID: 20065690
Also... there is something wrong with your DHCP Server configuration on the SBS because it's not passing along the WINS IP address to the client.

Please remove the two extra IP addresses ( 192.168.1.200 and 192.168.0.10) and then rerun the Configure Email and Internet Connection Wizard (CEICW -- linked as "Connect to the Internet on the To-Do list in the Server Management Console)

A visual how-to for that is here:  http://sbsurl.com/ceicw
A full networking overview for SBS is at http://sbsurl.com/msicw

Jeff
TechSoEasy
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Author Comment

by:Dbast
ID: 20068937
Gentlemen: Thank you all for your responses. The ethereal network sniffer is actually something our network person was deploying as I submitted the question, and he believes he's nailed down the problem:

----

I was able to find the location of the site which was providing the downloads.  

http://www.talkscomeplace.com/index.html

It looks like a subscription based service for downloading recordings such as the audio recordings stored on his computer.    I imagine it works similar to a newsreader and perhaps Thursday is the day it is configured to download new headers, or maybe thats the day of the week they publish new content, etc.    

The website looks like a delivery method for their media, and they probably supply a special program which does the downloading instead of a web browser.   If this is the case, then its probably occurring in the background which would explain why he is not aware of it.

--------

So I will be awarding the points to bluetab, since that's the solution that made the difference for us, even though it was a solution we had been working on before I submitted the question. But I'm sure all of this advice will be useful to someone out there! Thanks again.
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LVL 74

Expert Comment

by:Jeffrey Kane - TechSoEasy
ID: 20069436
Hmmm... that still doesn't change the fact that your DNS configurtion is not right.

Jeff
TechSoEasy
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Author Comment

by:Dbast
ID: 20078168
Jeff: I will push the network guy to look into that; he was pretty adamant that the setup is fine. I think the extra IPs are two Macs on the network, but I'm not 100 percent sure. --diane
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Expert Comment

by:Jeffrey Kane - TechSoEasy
ID: 20079679
Having Macs on the network wouldn't require at all to have separate IP addresses configured on your SBS's NIC.

Jeff
TechSoEasy
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Author Comment

by:Dbast
ID: 20081096
Jeff: Legitimate responses from the network guy?


1) The extra IP addresses are required for the server to exist in several subnets.   These are setup to maintain compatibility with the old network for remote access clients (through Megalodon) and to access the VOIP console.

2) WINS is an old NETBIOS service.  It has been replaced by DNS and Active Directory.   None of your PCs are NT4 or Windows 95/98, so theres no need for this.

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LVL 74

Expert Comment

by:Jeffrey Kane - TechSoEasy
ID: 20081282
" The extra IP addresses are required for the server to exist in several subnets."

This configuration will break the SBS's Configure Email and Internet Connection Wizard which is critical to ensuring that the SBS is both secure and correctly configured to handle your network communications.  Having multiple internal IP addresses will not only bog down that NIC's performance, it may very well cause it to lose packets on a regular basis.  I don't know what "Megalodon" is (other than a shark), but it would seem that if you have remote access clients they should be using your SBS's remote access technology which ensures both a secure and operational connection.

"WINS is an old NETBIOS service.  It has been replaced by DNS and Active Directory.   None of your PCs are NT4 or Windows 95/98, so theres no need for this."

That's a misconception because Exchange Server 2003 still uses WINS with Outlook.  I'd suspect that the DHCP scope may have been manually configured since the CEICW which normally handles this configuration wouldn't work due to the multiple IP addresses.

Jeff
TechSoEasy
0

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