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Setting static IP

Posted: Sun Mar 03, 2013 10:18 pm
by mbthomas
I am trying to set a static IP on a clerk's computer and I can't get the internet to work on this computer after I set the static IP. Using DHCP it will connect to the internet just fine. There are 4 computers in this building and the other 3 work just fine. The fm.lds.org site says this firewall has static IPs from 10.x.x.194 - .202. So far I used x.x.x.194, 195, and 197 with no problem. This computer would not work with .196. So I tired using .194 which I know works on another computer and it won't work on this one (I turned the first computer off so there wouldn't be an IP conflict on the network). All other settings (gateway, dns, etc) match other computers. It simply will not connect to the internet if I set any static IP. But I can successfully ping this IP from another computer. What can I do to get this computer to use a valid static IP?

Re: Setting static IP

Posted: Sun Mar 03, 2013 10:26 pm
by russellhltn
To successfully use static IP, you need the following: IP, Subnet, Gateway IP address, and DNS IP address. Miss or enter wrong values for any one of those and it won't work.

Re: Setting static IP

Posted: Sun Mar 03, 2013 11:02 pm
by Mikerowaved
May I ask what the purpose is of wrestling with static IP's when DHCP conveniently does this all for you?

Re: Setting static IP

Posted: Mon Mar 04, 2013 8:56 am
by mbthomas
russellhltn wrote:To successfully use static IP, you need the following: IP, Subnet, Gateway IP address, and DNS IP address. Miss or enter wrong values for any one of those and it won't work.


Got it all in correctly. I got those setting from the tm.lds.org page and verified they are identical on the other computers that do work.

Re: Setting static IP

Posted: Mon Mar 04, 2013 9:00 am
by mbthomas
Mikerowaved wrote:May I ask what the purpose is of wrestling with static IP's when DHCP conveniently does this all for you?


In one of the buildings I was dealing with internet access problems and one of the possible solutions from the global help desk was to set the clerk's computer to a static IP so that it was guaranteed an IP address and also free up other DHCP IPs for mobile devices. I decided those were excellent ideas and decided to implement that across the stake. Setting static IPs is simple enough that its really less than 2 minutes of my time at each computer. Accept for this one computer that just doesn't seem to like static IPs.

Re: Setting static IP

Posted: Mon Mar 04, 2013 9:53 am
by Mikerowaved
mbthomas wrote:In one of the buildings I was dealing with internet access problems and one of the possible solutions from the global help desk was to set the clerk's computer to a static IP so that it was guaranteed an IP address and also free up other DHCP IPs for mobile devices.

If there is ANY network problem where fixed devices are contending with mobile devices over available IP Addresses, then wouldn't the logical answer be to simply expand the IP pool to eliminate the conflict?

Re: Setting static IP

Posted: Mon Mar 04, 2013 12:47 pm
by mbthomas
Mikerowaved wrote:
mbthomas wrote:In one of the buildings I was dealing with internet access problems and one of the possible solutions from the global help desk was to set the clerk's computer to a static IP so that it was guaranteed an IP address and also free up other DHCP IPs for mobile devices.

If there is ANY network problem where fixed devices are contending with mobile devices over available IP Addresses, then wouldn't the logical answer be to simply expand the IP pool to eliminate the conflict?


Yep, that's one possible solution. And I did that as well. Another possible solution is to assign static IPs to the computers, which I also did.

Re: Setting static IP

Posted: Mon Mar 04, 2013 1:03 pm
by johnshaw
I also setup all my 'fixed' equipment with Static Addressing. Any clerk computer, network printer, etc... receive static addressing. All other devices are on dhcp. It helps eeek out just a few more IP's - can allow static devices to continue working when particular services on a firewall might be down, and helps me troubleshoot at times with others remotely and not have to worry about figuring out what IP the clerk computer might be on to have a 'known' quantity. Static Address provide much value in my mind.

Re: Setting static IP

Posted: Tue Mar 05, 2013 10:48 pm
by john84601
Couple of troubleshooting tips.

1) Try another IP from your static range.
2) Try pinging the default gateway.
3) If that works try pinging an IP on the internet (try 8.8.8.8).
4) Verify settings from a command prompt (ipconfig /all). Make sure you have values for DNS.
5) Try testing DNS from a command prompt. Type "c:\>nslookup www.google.com" and see if it returns a result.
6) Post the settings your using... maybe one of us will see something.
7) If your really desperate... download the latest drivers and reload them.

Hope you get it worked out :)

Re: Setting static IP

Posted: Wed Mar 06, 2013 8:55 am
by jbean86
I have no troubleshooting suggestions that already haven't been given. My recommendation is that if dynamic works, stick with dynamic. Generally, setting computers to static is only recommended as a last resort by the GSC, especially when the firewall is a Cisco 881, not a Pix or ASA. Because the 881 has no license limit from Cisco, the DHCP pool can be expanded to meet and exceed the needs of the building.

If the DHCP pool is sufficiently large, the advantages of static over dynamic are minimal to non-existent, but there are two major drawbacks:

1) The potential for IP conflicts. Computers aren't always on. For somebody setting up a new printer or something at a static IP, unless they know or are told beforehand, there's no way for them to tell that static IP is already in use by a computer that is currently off.

2) Time/effort spent. Setting a device to static is fairly simple, until the firewall is switched out, or an 881 has problems, gets reset and reactivated, and ends up with a different IP range. Each static device will be offline until each is reconfigured to the new range, or to dynamic. Plus you have to keep track of what devices are set to which static IP, pass that on to the next stake technology specialist, etc.