Static IPs no longer log on...?

[Kenneth]

Howdy,

We have 5 systems behind a LinkSys router.

All systems have static IP addresses assigned, and the
router, of course, gets its IP address from the provider.

Today, we found that all five systems failed to log on to
the Internet.

After quite a bit of experimentation, we found that if the
systems were set to DHCP, they could log on, but if they
were set back to static IP addressed, they could not.

What might be the cause...?

(And yes, we do need the static assignments.)

Many thanks,

 

[Lanwench [MVP - Exchange]]

Howdy,

We have 5 systems behind a LinkSys router.

All systems have static IP addresses assigned, and the
router, of course, gets its IP address from the provider.

Today, we found that all five systems failed to log on to
the Internet.

I've never had to log onto the Internet myself. Who sets the passwords? ;-)

Kidding aside, what testing did you do? Could you ping the LAN IP of the
router from the workstation? How about a public DNS server IP address? How
about www.google.com?

After quite a bit of experimentation, we found that if the
systems were set to DHCP, they could log on, but if they
were set back to static IP addressed, they could not.

Did you compare the output of an ipconfig /all while using DHCP and static?

What might be the cause...?

(And yes, we do need the static assignments.)

What for? If you need non-changing IP addresses on workstations for some
reason, it's much better to set up reservations on the DHCP server (i.e.,
MAC address blahblahblah always gets 123.123.123.123, etc). This makes your
admin work a lot easier, even on a small network.

 

[Kenneth]

Hi again,

Please see my comments inline below... (and accept my
apologies if this is a duplicate.)


On Tue, 13 Jan 2009 13:16:16 -0500, "Lanwench [MVP -
Exchange]"

I've never had to log onto the Internet myself. Who sets the passwords? ;-)

Kidding aside, what testing did you do? Could you ping the LAN IP of the
router from the workstation? How about a public DNS server IP address? How
about www.google.com?


Did you compare the output of an ipconfig /all while using DHCP and static?

That seemed like a great idea, and I had not thought to try
it. In the interim I had set our systems to DHCP so that we
could use them while we tried to figure out the cause of the
problem.

So, moments ago, I reset this system to static IP and went
to the command line to run the ipconfig /all.

But out of habit, before doing that, I pinged a website,
and, would't you know it, the ping succeeded...!

I will be back in the office tomorrow to see if the other
systems have been so miraculously cured.

What for? If you need non-changing IP addresses on workstations for some
reason, it's much better to set up reservations on the DHCP server (i.e.,
MAC address blahblahblah always gets 123.123.123.123, etc). This makes your
admin work a lot easier, even on a small network.

When I used the term "static assignments" I guess I should
have said "non-changing IP addresses."

But I do need a bit more information about your suggestion
above:

I think I know how to assign an IP address to a MAC address
in the router setup.

But having done that, how would I set up the individual
systems? That is, how would each NIC know the IP address
bound to it?

Sincere thanks, as before,

 

[Kenneth]

But having done that, how would I set up the individual
systems? That is, how would each NIC know the IP address
bound to it?

Hmmm... Would it just grab the proper address if it were set
to DHCP?

Thanks again,

 

[John Wunderlich]

Hmmm... Would it just grab the proper address if it were set
to DHCP?

Exactly.

When the Computer uses DHCP to ask the router for an IP address, the
router recognizes that its MAC address is on the reserved list and
continues to use the DHCP protocol to assign it its designated address
(along with the correct DNS server information and Gateway address).

If you fix the IP address at the computer (ie., disable DHCP), you must
also specify a DNS server address and a Gateway address in order to
connect to the internet through a router.

HTH,
John

 

[smlunatick]

Hmmm... Would it just grab the proper address if it were set
to DHCP?

Thanks again,

Are the PCs connecting via a wireless adapters? I personally had a
problem where my anti-virus was the cause of not getting the IP
address working correctly. It needed to be to trust the wireless
network name (SSID) as well as the IP address of the wireless router
(aka gateway.)

 

[Kenneth]

Exactly.

When the Computer uses DHCP to ask the router for an IP address, the
router recognizes that its MAC address is on the reserved list and
continues to use the DHCP protocol to assign it its designated address
(along with the correct DNS server information and Gateway address).

If you fix the IP address at the computer (ie., disable DHCP), you must
also specify a DNS server address and a Gateway address in order to
connect to the internet through a router.

HTH,
John

Hi John,

Many thanks.

I will set up the MAC address assignment shortly.

All the best,

 

[Kenneth]

Are the PCs connecting via a wireless adapters? I personally had a
problem where my anti-virus was the cause of not getting the IP
address working correctly. It needed to be to trust the wireless
network name (SSID) as well as the IP address of the wireless router
(aka gateway.)

Hi again,

No... At the time of the problem, all were hard wired.

All the best,

 

[Kenneth]

Exactly.

When the Computer uses DHCP to ask the router for an IP address, the
router recognizes that its MAC address is on the reserved list and
continues to use the DHCP protocol to assign it its designated address
(along with the correct DNS server information and Gateway address).

If you fix the IP address at the computer (ie., disable DHCP), you must
also specify a DNS server address and a Gateway address in order to
connect to the internet through a router.

HTH,
John

Hi again,

I just had a few minutes, and thought I would check out the
process for assigning IPs to MAC addresses.

I have a cheapo router (Linksys BEFSR41) and based on a
careful review of its manual, it can't do the deed.

Might there be another way?

Thanks again,

 

[John Wunderlich]

Hi again,

I just had a few minutes, and thought I would check out the
process for assigning IPs to MAC addresses.

I have a cheapo router (Linksys BEFSR41) and based on a
careful review of its manual, it can't do the deed.

Might there be another way?

In that case, you must set up static IP addresses on machines that
can't use DHCP (ie. need fixed IPs). If you do it correctly, it should
work. You always must specify three things: an IP address, a Default
Gateway on the same subnet, and a DNS Server for it to work properly.

The following should work with a BEFSR41 w/ default configurations...
In the network connections control panel, Right-click on the connection
that you're configuring and select "Properties", then scroll down in
the window (if necessary) and double-click TCP/IP.
Click the "Use the following IP address".
For IP address, enter the address 192.168.1.xx
where 'xx' is between 2 and 99 (avoids conflict w/ DHCP)
For Subnet Mask, enter 255.255.255.0
For Default Gateway, enter 192.168.1.1

Click "Use the following DNS server addresses" checkbox.
For "Preferred Server", enter 192.168.1.1
(I believe this to work on BEFSR41)
Alternatively, you can try an openDNS server of 208.67.222.222.

This should be everything that you need to configure.

HTH,
John

 

[Kenneth]

In that case, you must set up static IP addresses on machines that
can't use DHCP (ie. need fixed IPs). If you do it correctly, it should
work. You always must specify three things: an IP address, a Default
Gateway on the same subnet, and a DNS Server for it to work properly.

The following should work with a BEFSR41 w/ default configurations...
In the network connections control panel, Right-click on the connection
that you're configuring and select "Properties", then scroll down in
the window (if necessary) and double-click TCP/IP.
Click the "Use the following IP address".
For IP address, enter the address 192.168.1.xx
where 'xx' is between 2 and 99 (avoids conflict w/ DHCP)
For Subnet Mask, enter 255.255.255.0
For Default Gateway, enter 192.168.1.1

Click "Use the following DNS server addresses" checkbox.
For "Preferred Server", enter 192.168.1.1
(I believe this to work on BEFSR41)
Alternatively, you can try an openDNS server of 208.67.222.222.

This should be everything that you need to configure.

HTH,
John

Hi John,

I do appreciate your comments, but I had done all that
already... long ago, and it worked fine.

For the last three years or so, I had our 5 systems working
happily with static IP addresses configured as you have
described.

Then, a few days ago, all 5 lost Internet.

Since that time, I find that I can only get them to see past
the router if I set them to use DHCP.

Do you have any thoughts about what could have caused that
situation?

Many thanks,

 

[Jack \(MVP-Networking\).]

Hi
Many newer Router can do Reservation of IP within the DHCP (aka Static DHCP
IP), the Router that you have can not.
Leave the DHCP On with a range of few computers, and then configure the
computers with static IP of the same subnet but above the range of the DHCP.
Dont forget to put the Router's core IP as the default gateway.
Otherwise it might be a good time to get a good Router that can do Static
DHCP.
Jack (MS, MVP-Networking)

 

[Kenneth]

Hi
Many newer Router can do Reservation of IP within the DHCP (aka Static DHCP
IP), the Router that you have can not.
Leave the DHCP On with a range of few computers, and then configure the
computers with static IP of the same subnet but above the range of the DHCP.
Dont forget to put the Router's core IP as the default gateway.
Otherwise it might be a good time to get a good Router that can do Static
DHCP.
Jack (MS, MVP-Networking)

Hi Jack,

I thank you for your comments, but...

You are suggesting just the setup that I have had for the
last many years.

It always worked properly.

The problem is that now, for some reason, none of these
machines can see past the router if they have a static IP
assigned. If I change their setup to DHCP, they have
Internet immediately.

Might you have some thoughts about what could cause that to
happen?

All the best,

 

[John Wunderlich]

Hi John,

I do appreciate your comments, but I had done all that
already... long ago, and it worked fine.

For the last three years or so, I had our 5 systems working
happily with static IP addresses configured as you have
described.

Then, a few days ago, all 5 lost Internet.

Since that time, I find that I can only get them to see past
the router if I set them to use DHCP.

Do you have any thoughts about what could have caused that
situation?

Many thanks,

If it's like the BEFSR41 router like I have, have you tried
unplugging the power from the router for several seconds then
reconnecting? I have to do this about once every month or two.

The BEFSR41 router also has a filter setting which will keep
designated ranges of IP addresses from accessing the internet. Did
you check this?

Other than that, no clue.

--John

 

[Jack \(MVP-Networking\).]

Hi
Routers are actually mini computers with CPU, Memory, and OS embedded in the
firmware.
Almost Every thing (including computers, Routers, and Neurowares) works,
until it does Not.
You can try to Hard Reset the router and reconfigure.
Otherwise, you are spending too much energy on a piece of Plastic with
Silicon chips that worth $10-$15.
Here is a new very good Wireless Router for $34.99 after rebate and free
shipping.
http://www.newegg.com/Product/Product.aspx?Item=N82E16833320023
$34.99, one dinner in Low/Medium priced Restaurant (with No Wine) .
Jack (MS, MVP-Networking)

 

[Kenneth]

If it's like the BEFSR41 router like I have, have you tried
unplugging the power from the router for several seconds then
reconnecting? I have to do this about once every month or two.

The BEFSR41 router also has a filter setting which will keep
designated ranges of IP addresses from accessing the internet. Did
you check this?

Other than that, no clue.

--John

Hi again,

I did power it down a number of times in the course of
trying to diagnose this thing.

And, nothing is filtered.

This is a weird one, and I thank you for your efforts,

 

[Lanwench [MVP - Exchange]]

Hi again,

I did power it down a number of times in the course of
trying to diagnose this thing.

And, nothing is filtered.

This is a weird one, and I thank you for your efforts,

Try posting an unedited ipconfig /all from the PC while on DHCP, and while
it has a static.

 

[Kenneth]

On Thu, 15 Jan 2009 16:22:51 -0500, "Lanwench [MVP -
Exchange]"

Try posting an unedited ipconfig /all from the PC while on DHCP, and while
it has a static.

Hi again,

I am happy to do that, but other than a screen shot (which,
I assume could not be posted here) how can I provide that
info?

Is there a better approach than simply copying it? (which,
of course, I would do...)

Thanks as before,

 

[John Wunderlich]

On Thu, 15 Jan 2009 16:22:51 -0500, "Lanwench [MVP -
Exchange]"

Try posting an unedited ipconfig /all from the PC while on DHCP,
and while it has a static.

Hi again,

I am happy to do that, but other than a screen shot (which,
I assume could not be posted here) how can I provide that
info?

Is there a better approach than simply copying it? (which,
of course, I would do...)

Thanks as before,

To do a copy in a Command window, right-click anywhere in the window
and select "Mark". Then use your left mouse button to drag over text,
then hit the "Enter" key. This will do the equivalent of a "Copy".
Then paste it in any other window as usual.

HTH,
John

 

[Lanwench [MVP - Exchange]]

On Thu, 15 Jan 2009 16:22:51 -0500, "Lanwench [MVP -
Exchange]"

<snipped for length>


If it's like the BEFSR41 router like I have, have you tried
unplugging the power from the router for several seconds then
reconnecting? I have to do this about once every month or two.

The BEFSR41 router also has a filter setting which will keep
designated ranges of IP addresses from accessing the internet.
Did you check this?

Other than that, no clue.

--John

Hi again,

I did power it down a number of times in the course of
trying to diagnose this thing.

And, nothing is filtered.

This is a weird one, and I thank you for your efforts,

Try posting an unedited ipconfig /all from the PC while on DHCP,
and while it has a static.

Hi again,

I am happy to do that, but other than a screen shot (which,
I assume could not be posted here) how can I provide that
info?

Is there a better approach than simply copying it? (which,
of course, I would do...)

Thanks as before,

To do a copy in a Command window, right-click anywhere in the window
and select "Mark". Then use your left mouse button to drag over text,
then hit the "Enter" key. This will do the equivalent of a "Copy".
Then paste it in any other window as usual.

HTH,
John

Yes, but that isn't necessary here. Kenneth, try this in a command prompt:

ipconfig /all >c:\myfilename.txt

....open that file in notepad, select, copy & paste