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Un-possable.


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#1 YetAnotherDave

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Posted 05 February 2015 - 04:24 PM

Hello,

 

Let me tell you a story. I am at work. Everything is fine and dandy. Then, to my surprise. Internet stops working. As an aspiring IT guy i think to myself "Yay! now I'm getting payed to fix my computer"

 

I start troubleshooting. Run an ipconfig. it tells me that my lan ip is 172.15. yadda yadda. 

Check the router: Router is giving out 192.168.0.1-90 all other settings are fine. no static ip everything is running DHCP

5 other computers at work with no issues. I say "must be a problem with my computer." so I reformat

 

Same issue, Same ip.

 

There is a unused server (power edge) on the network. unplugged it and internet was returned. Yay

 

Ipconfig: same 172 address yet i have internet. 

 

Call my  brother (Actual pro IT guy) tells me that its impossible for your computer to work on a network with an invalid ip and i know how to fix it.

 

so we run through a few steps flushing my ip and renewing and five or six other things. 

 

Same ip. "you hacked i gotta go" 

 

open coworkers laptop he also has a 172 ip address. he has internet.

 

Asked my boss if anything on the network can give out IP's (we have a d-link poe/switch and a verint DVR) nothing is giving out ips.

 

A few days latter the router died and we got a new one. logged on and my computer worked fine. Must have been the router. 

 

Bosses computer now has a 172. ip address. 

 

If i unplug the router form the switch then it fixes the problem however we need the switch plugged in so we can have our ip cameras and printer working 

(no the cameras nor the dvr or the secruity system are giving out ip's they were all removed in testing)

Far as I can figure its something to do with the switch.

but its a switch.

Where is the 172 coming from? 

Why does every one say this is the oddest thing they have ever heard?

Why did you read this stupid. Broken up story that has no story type bits. 

How do I fix'it.

 

 

 

TLDR: I have a 172. ip address being assigned by a ghost device on a DHCP network giving out 192 addresses.

Any ideas? 

 

 

All computers are running Windows 7 or 8. 

D-link x-stack model DES-3200-52P

 



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#2 CaveDweller2

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Posted 05 February 2015 - 05:16 PM

On a PC that works, do a tracert to yahoo.com. 


Hope this helps thumbup.gif

Associate in Applied Science - Network Systems Management - Trident Technical College


#3 YetAnotherDave

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Posted 05 February 2015 - 05:27 PM

 
 
Tracing route to yahoo.com [98.139.183.24]
over a maximum of 30 hops:
 
  1     2 ms     3 ms     2 ms  192.168.0.1
  2    41 ms    27 ms    27 ms  boid-dsl-gw15.boid.qwest.net [184.99.64.15]
  3    27 ms    27 ms    27 ms  boid-agw1.inet.qwest.net [184.99.65.113]
  4    42 ms    41 ms    41 ms  sea-brdr-02.inet.qwest.net [67.14.41.18]
  5    41 ms    41 ms    41 ms  te8-3-10G.ar5.SEA1.gblx.net [64.208.110.141]
  6   113 ms   108 ms   107 ms  yahoo.ethernet10-1.ar9.nyc1.gblx.net [208.178.19
4.102]
  7   109 ms   114 ms   107 ms  ae-4.pat1.bfz.yahoo.com [216.115.97.211]
  8   108 ms   111 ms   107 ms  ae-3.msr2.bf1.yahoo.com [216.115.100.31]
  9   108 ms   108 ms   108 ms  xe-1-2-1.clr1-a-gdc.bf1.yahoo.com [98.139.130.7]
 
 10   109 ms   108 ms   108 ms  UNKNOWN-72-30-22-X.yahoo.com [72.30.22.13]
 11   108 ms   111 ms   115 ms  po-11.bas2-7-prd.bf1.yahoo.com [98.139.129.179]
 
 12   108 ms   108 ms   108 ms  ir2.fp.vip.bf1.yahoo.com [98.139.183.24]
 
Trace complete.


#4 Wand3r3r

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Posted 05 February 2015 - 06:56 PM

Is this a wired or wifi connection?

When you get a 172 network what is the gateway ip?

Can you ping the gateway?


Edited by Wand3r3r, 05 February 2015 - 06:57 PM.


#5 CaveDweller2

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Posted 05 February 2015 - 08:07 PM

Was that from one that gets a 172 address but still has internet access?


Hope this helps thumbup.gif

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#6 YetAnotherDave

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Posted 06 February 2015 - 10:49 AM

I have received a 172 from both wired and wireless. 

 

And no the computer i used doesn't have the 172. After we changed the router I no longer had the 172 with internet. 

 

I will try to get a 172 trace (that makes so much more sense *facepalm*)



#7 YetAnotherDave

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Posted 06 February 2015 - 12:14 PM

Currently I can wire in to get the 172 ip address however it doesn't get me online. tracert fails.
 
Boss that got it wireless isn't in right now but I had to assign him an address to get internet. 
 
While I was on the 172 address I tried to assign myself a new address on the 172 string to see if I could recreate the effect of 172+net
 
I received an error message saying that I was trying to use 2 gateways and doing so would prevent internet. 
 
currently (to my knowledge) there is only one gateway on the system. Being the router I am connecting to. I tried to map the network.
 
Network map shows my laptop connecting to the switch (I'm plugged into the router) from that switch to another switch then to the router. 

 

from there it goes back through the second switch and to another (yet the same) router to the gateway. 

 

 

Some more messing around: If I remove the d-link switch there is no problem. Wired or wireless. 

 

Does anyone know if the D-link DES-3200-52P has a routing function? The only ting I can find is a setup video in Spanish. :/

 

 

One other thing to note is I unplugged the voip system from the net work and now I can't get my laptop to generate a 172. Boss still does. His computer won't give him internet.

Also when I connected DHCP on his laptop it kept trying to identify the network every few seconds. Not sure what that was about or if it will help track down the probem



#8 Wand3r3r

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Posted 06 February 2015 - 01:38 PM

 http://www.dlink.com/-/media/Business_Products/DES/DES%203200%20Series/Datasheet/DES_3200_Series_Datasheet_EN_EU.pdf

 

No mention of being a dhcp server.  Do you have managed switches?  If you do and can identify the mac address of the 172 router you can trace to what port this rouge device is attached.

 

I suspect someone brought in their own wifi router and hooked it up to your network.  This is assuming you aren't running ip phones and they are in the 172 network.



#9 YetAnotherDave

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Posted 06 February 2015 - 05:13 PM

We have one ip phone yes. ooma brand. We are not a big company only 7 of us and of them only 3 of us are in the office at most. mot a big building and not a big network. 

 

Definitely not another router from our side and no, we have no managed switches. 



#10 Wand3r3r

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Posted 06 February 2015 - 05:50 PM

What subnet are the phones on?

How many switches do you have?

 

You may have to do this the hard way which is you get a laptop that has a 172 address, note the gateway and do a ping 172 gateway address -t so it keeps running.

You start this on your backbone switch.  You disconnect one connection at a time, starting with any switches connections coming off this switch, until the ping fails.  You will either isolate to this switch or determine its a downsteam switch of which you will repeat this until you have isolated what port is housing the 172 dhcp server.  Then its just a matter of seeing in what room that port terminates.



#11 CaveDweller2

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Posted 08 February 2015 - 09:23 AM

Have you tried surfing into the default gateway of the 172 network? It might give you an idea of the brand device it is. Least then you'll know what you are looking for.


Hope this helps thumbup.gif

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#12 YetAnotherDave

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Posted 09 February 2015 - 01:07 PM

Think I've got it. 

There is only one switch and an ooma Voip device. Witch the ooma device had the cords backwards form incoming to outgoing. Got that flipped this morning and it seems to have fixed it.

 

One thing to note.

 

I tried to log into the ooma via direct link and it gave me a 162 address when its default is set to a 172. 

 

Thanks for all your help. You guys are awesome!



#13 Wand3r3r

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Posted 09 February 2015 - 02:30 PM

Maybe that's its management port though that ip address is public not private which adds to the mystery.

 

How did the cords get switched?



#14 YetAnotherDave

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Posted 09 February 2015 - 05:12 PM

They may have been that way sense installation. 

 

The particular device is supposed to be placed between the modem and the router. Having an "internet" and "network" ports

 

We have a modem/router combo so it should just be in the "network" slot. (I think)

 

I have only been working here for four months. It may have been that before we had so many computers interacting with the network there just wasn't enough traffic

to cause interference.  

 

I still haven't been able to log on to check the subnet however its working so I'm not complaining. 



#15 CaveDweller2

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Posted 09 February 2015 - 07:45 PM

You have the business Ooma series? I saw that it plugged in between the modem and router......but I didn't see that it gave out IP's so still not sure where that 172 address would be coming from.


Hope this helps thumbup.gif

Associate in Applied Science - Network Systems Management - Trident Technical College





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