Cisco DHCP Conflict Log Filling Up?
Mar 15, 2011
I have a Cisco 3750 running DHCP. We have a lot of guest users on the network, so the DHCP conflict table fills up quickly, and when it does, users can not get on the wireless network. I have to go in and clear the DHCP conflict log. (clear ip dhcp conflict *) and the problem is resolved. I see in the Cisco documentation if you don't have a DHCP database agent configured you should disable that log. I just want to make sure what the steps are and the ramifications are of disabling that log. Would IP address's still be freed up to use on the network? It also said about enabling 'ip dhcp ping' so DHCP will ping the address first to see if it's available.
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Jun 13, 2012
DHCP conflict on 881-W with the internal AP?I have (12) 881-W chassis in the field. They are running DHCP services to the wired users as well as to the internal AP for reachability / management / etc. The scope for the internal AP is a /30 so only one address is in the scope and it is intended for the internal AP. This serves a a point to point link between the internal AP and the internal Router inside the 881-W chassis.
Somehow the 881-W DHCP server is getting out of synch and a conflict is occurring. It seems at some point, either at boot-up or lease expiration/renewal, the DHCP server is performing a ping to verify that the address is not in use. The AP has this address assigned prior and replies to the ping causing a conflict. I noticed an AP down today, checked the 881-W uptime and the conflict correlates to the same time. I have to manually clear the conflict and everything works as it should.The existing 12 881-w's could grow to 100's over time, so the manual intervention of clearing the conflict is not going to scale. I really want to stay away from static reservations.
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Apr 21, 2013
We have VSS configured between Cat-6509 switches (s72033-advipservicesk9-mz.151-1.SY.bin)..For the voice vlans,dhcp scope is configured within VSS and ip addresses are assigned to ip phones from these pools configured within VSS.Cat 3750 stack is connected with dual links to this vss. IP phones are connected to cat 3750 switches and desktop is connected back to IP phone. For data vlans IP addresses are assigned from external dhcp server.
Currently we are facing lot of ip conflicts for ip phones and after clearing the dhcp conflicts, IP phones starting getting IP addresses..(sufficient IP's do available in the dhcp scope for IP address assignment). (What exactly the role of no ip dhcp conflict logging command......)
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Oct 8, 2012
Im setting up SBS 2011 in a new office. From what I understand, SBS 2011 needs to be the network DHCP server for everything to run well under Active Directory. The conflict is with a FIOS router, that also �needs� to be the DHCP server in order to communicate with a set-top box (MOCA bridge.) Verizon lists a handful of network configurations with multiple routers that might work, although completely unsupported. Is it possible for router, SBS2011, and set-top box to coexist in harmony on the same network (preferably keeping DHCP server on the SBS box)?
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May 10, 2013
I configured an DHCP server on cisco 3750 switch . Wher in w3750 gets connected to plain l2 switch 2960 on floor and machine gets connected to 2960 port. [code] Below is the description of problem:
-> The Cisco 3750 switch is the DHCP server. VLAN 108 is named as internet vlan.
-> Ports in Cisco 2960 switch has been configured with "switchport access vlan 108".
-> There were no problems at all and everything had been working smoothly.
-> 3 days back, users started complaining that they couldn't access the internet. Up on troubleshooting the issue, I found out that there was an issue with the DHCP server as the computer couldn't get any IP address at all. After setting static IP address, the internet started working again.
If I bind IP to MAc address reservation on core 3750 switch for some time of moment it works but after that machine gets unreachable .I restarted the 3750 switch and also all the 2960 switches over the weekend, however, the issue still hasn't been resolved yet. I did issue the command "clear ip dhcp conflict *", clear ip dhcp binding * but no joy at all.
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Dec 8, 2012
I have this routing table which I need to fill in for the network shown in the image attached. guide me to some good resources to understand
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May 3, 2012
It looks like both my HSRP Interfaces (VLAN 600 & 700) cycle through standby --> active ---> speak continuously on one of the two switches. What can be causing this?
*May 4 06:41:24.883: %HSRP-5-STATECHANGE: Vlan700 Grp 0 state Speak -> Standby
*May 4 06:41:33.671: %HSRP-5-STATECHANGE: Vlan700 Grp 0 state Standby -> Active
*May 4 06:41:33.671: %HSRP-5-STATECHANGE: Vlan700 Grp 0 state Active -> Speak
*May 4 06:41:34.251: %HSRP-5-STATECHANGE: Vlan700 Grp 0 state Speak -> Standby
*May 4 06:41:47.691: %HSRP-5-STATECHANGE: Vlan700 Grp 0 state Standby -> Active
*May 4 06:41:47.703: %HSRP-5-STATECHANGE: Vlan700 Grp 0 state Active -> Speak
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Jul 28, 2011
In application udp port listening with 3330 i am sending udp request from port 0.0.0.0:3330 to 0.0.0.0:3330 that is same port in the same machine, application works fine with udp sending and receiving also fine, for clarification. s there any conflicts in the communication ?
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Apr 22, 2011
When I sign on the internet, I get a Windows System Error - "There is an IP address conflict with another system on the network." I went to command prompt and typed "ipconfig /renew" but the response was "No operation can be performed on Local Area Connection while it has media disconnected".
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Apr 16, 2011
A couple of days ago my internet was working fine at a speed of around 5mps, I then received a message informing me of an ip conflict, since then my internet has really slowed down to 0.12mbs.
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Jan 4, 2012
Problem with a conflicting IP address. Basically on a normal running day my wireless is switched on and connected perfect to my internet, however if i want to download any large files i plug my Ethernet to my laptop and disable the wireless from my laptop, instantly then the LAN connection kicks in and im on the internet again as i find download speeds are faster through a LAN. However today my wireless is fine but the second i switch to LAN the ! symbol appears and a message says their is an IP conflict.
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Jan 22, 2012
i cant connect to the internet every time i open my laptop. so i have to disable the connection first and then diagnose it to connect to the internet. Pop ups about IP conflict sometimes occur.. what should i do? i already tried ip/release and ip/renew but it didn't work..
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Jan 29, 2013
I've got a wireless network, consisting of two Windows 7 PCs, a wireless printer, an Android tablet and an iPhone. The PCs are always on the network; the other devices only connect occasionally. The router is a Dynamode R-ADSL-C4-W-G1. IP addresses are assigned by DHCP, and both PCs are set up to get an IP address automatically.Now and again, I get an error message on my PC, saying Windows has detected an IP address conflict on the network. I looked in the System Event Log, and found the following message: Quote:The system detected an address conflict for IP address 10.0.0.3 with the system having network hardware address [hex number here]. Network operations on this system may be disrupted as a result.
When I checked in the router settings, I found 10.0.0.3 had been assigned to the other PC, which also has the hardware address given in the error message - I'm not sure how that constitutes a conflict!When I get this error message, I never encounter any connectivity problems - i.e. both machines can still access the internet.
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Jan 12, 2012
I have a Cisco ASA5505 running 8.2(1) and I am using ASDM to manage the firewall. I have a Linux VPN server on the inside with and IP address of YYY.YYY.YYY.39 with a static NAT to the outside with an address of XXX.XXX.XXX.171 . I have a site to site VPN tunnel which terminates on the outside of the ASA on the outside interface XXX.XXX.XXX.190 .Traffic from the YYY.YYY.YYY.0/24 network can't transverse the site to site VPN as there is a conflict of IP address's on the far side so it is natted via a dynamic policy to host address ZZZ.ZZZ.ZZZ.100, Users remote into the inside(YYY.YYY.YYY.0/24) for support via the Linux VPN server (.39) and then need to communicate down the site to site VPN. The problem is that the static NAT for the incomming connections takes preference and bypasses the site to site VPN tunnel for outbound traffic. I tried to create a policy Static nat but it tries to modify the static nat that handels the incomming traffic to the Linux server.
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Jun 26, 2012
I recently changed my home configuration. I have AT&T DSL and I replaced my 2WIRE gateway with an AT&T provided Motorola Modem and a Linksys E2500 router on Sunday. For the last few days, all has been good. Last night and this morning, one of the computers in the house began getting IP conflict messages. The computer is provided by my company and uses the Cisco VPN client. I am not sure if it is conflicting because of the VPN (only seems to happen when it's connected) or with one of the other devices on the network (i have four other computers, a game system, and a few phones on the network).
Is there a way to prevent a conflict from happening again? My work requires me to have a constant connection for days at a time and these IP conflicts are causing constant headaches. Would creating a static IP address on the work computer outside of the DHCP range clear this up?
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Aug 5, 2011
I'm trying to perform ping to another network segment using nat to those devices but the ipaddress i assigned are the same as the segment i am trying to monitor is there anyway to overcome this?
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Jul 25, 2012
Can an IP conflict cause network issues for computers other than the devices that have the same IP? I have resolved an issue where someone was testing a device on our network and assigned a static IP that was already in use by one of our printers. Specifically, I am curious if the IP conflict could have caused issues with mapped network drives for other computers. I just seemed to have network gremlins for the 2 days of the IP conflict.
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Oct 26, 2012
I've been getting a popup error message for about a week:"There is an ip address conflict with aother system on the network". This is only for 2 desktop PCs with wired ethernet connections. Wireless devices are fine with no error message. The wired LAN PCs basically lose all network capability. Reboot fixed it, but it returned every time it was rebooted.I have a Virgin Media Superhub with another router configured as an access point. To cut a long story short, after trying to reset everything, re-installing network adapters & swapping ports, I decided to set the Superhub to Modem Mode, and re-configure the access point router to act as a standard wireless router. In other words renewing the whole network's LAN IP addresses.I now don't lose network capability, but the error message is still appearing on both wired LAN PCs. I use the Fing app on my android phone which lists IP addresses for all devices on the network, wired and wifi, and no 2 addresses are the same, which suggests that DNS is doing its job.
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Mar 20, 2011
I have been having router/wireless internet issues since my internet provider had to come out and fix the outside lines. Ever since then I get the Network Error: "Windows has detected and IP address conflict" whenever my laptop and my wife's try to use the wireless at the same time. I have tried release/renew of my IP address and also reseting my router to factory settings to no avail.
Computer info and ipconfig/all:
Tech Support Guy System Info Utility version 1.0.0.1
OS Version: Microsoft Windows 7 Home Premium , 64 bit
[Code].....
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Jul 10, 2012
[code] Whenever I am browsing online, every once in a while the internet just cuts out. It still says I am connected to my wifi network, but there is "limited or no connectivity." Whenever it happens, everything on the network loses its internet at the same time. In the household, there is one PC (mine), one Mac (my wife's), one iPod touch, and 2 iPhones that all connect to the wifi. The vast majority of the time, when this problem occurs, simply unplugging the router and then plugging it back in fixes the issue.Sometimes however things are different. Especially lately, I sometimes get an "IP conflict" error message. It says another device on the network is using the same IP address. Sometimes with this error simply unplugging and replugging in the router works. Sometimes the router has to be reset twice before things start working again with this error. The error doesn't happen every time the disconnect occurs, but it seems to be getting more frequent lately.Sometimes the disconnect happens when I am playing an online game that requires a constant connection to the internet. Sometimes this goes as usual, where a single router reset fixes the problem. However, sometimes this situation gets more complicated. One game in particular (League of Legends, if it matters) has this problem all of the time. When the internet disconnects while this game is playing, I do not get the "limited or no internet" warning. Instead, the computer seems to think that it is connected, and that the internet is working.
During this scenario, resetting the router once is never enough. After resetting once, the wifi reconnects and now it realizes something is wrong. After the first reset, the computer seems to "realize" something is wrong after all, and I am connected to the network but this time with the "limited or no internet" warning. A second router reset after this usually fixes the problem.Last night the worst disconnect happened yet. It was in the middle of a game, and the internet cut out, with no warning on the network. After one router reset, the wifi network reconnected immediately with an "IP address conflict" error, and then I was connected with "limited or no internet" on the network. I did the second router reset as usually required, but nothing happened. After a second and a third reset, there was still a permanent "limited or no internet" warning.I tried hardlining in directly to the modem and there was still no internet. Running the network diagnostic on my laptop fixed it however and I was connected to the internet. However, wifi still would not work, even after trying the diagnostic again. Running the diagnostic came up with an error that the DNS server was not responding and so nothing could be done.This time I reset everything. Unplugged both the router and the modem and left them unplugged for 30 minutes. When I turned everything else on again, same issue. Connected to the wifi network, but "limited or no internet." I unplugged everything again, left them overnight, and this morning after plugging everything back in the internet was back.A few final points I think might be relevant:
1) When checking the system event logs, it's usually a DNS error that I get (see event logs, 1st attachment).
2) This disconnect error seems to be more prevalent when more devices are on the network. As I said, they have gotten more frequent lately, especially the IP conflict warnings, since the 2 iPhones were added a few weeks ago. 5 months ago when it was only my PC on the network, these issues were practically non-existent.
3) It's a Belkin wireless g-plus router. Model # F5D7231-4 version 1213. It is an older router.
4) This has been happening for almost a year, but just recently gotten so bad I have to get this fixed, especially after last nights that could not be reset no matter what.
5) I'm not sure the disconnects have ever happened why the PC is not connected. That may not be relevant however, because my PC is almost always on since I work from home, while the iPhones, iPod touch, and my wife's Mac are only connected periodically.
6) This error has occurred while my PC is the only device connected to the wifi network, but it seems much less frequent.
7) The time the error seems most likely to occur is when another device connects to the network, such as when my wife first gets home from work. This is not exclusive however, and the DC's can happen at any time.
I've seen that people want ping tests and ipconfig /all tests so I will post mine. I will edit my post with the same tests done the next time this dc happens. I've also included a screenshot of that xirrus wifi program. [code]
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Oct 19, 2012
There are about 3 laptops, one desktop, and 2 gaming consoles that are using the router. Everything connects fine expect the one laptop. It is an ASUS laptop running Windows 7. Whenever the laptop is going to connect to the internet every other device using the internet is stalled for a few moments, then reconnects. The computers then give the IP Address Conflict message. This is extremely frustrating. Sometimes it happens when people are accessing the Web for college assignments, and sometimes gaming, which is annoying to get disconnected from. I have tried to release / renew the IP, but it tells me it can't complete the process.
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Mar 17, 2013
I have a laptop running xp on a home network using cisco-linksys wrt310n router. A couple months ago I added another laptop running win7 to the network, and since then I have been getting ip address conflict errors once or twice a day. Both machines are set to obtain ip address automatically
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Mar 7, 2011
I have two Netgear routers (N150 and DG834) and want to set them up so that in my office (external to the house) I have wired internet connection and in the house wireless, the office is too far away to run the wireless for the house there. The router in the office is connected to the ADSL line with the router in the house connected to it via a network cable.?I have disabled wireless on the office router however when i try to run both routers together I get an IP Address Conflict, I know I need to change the IP address so that they don't conflict but when I have tried this it hasn't worked and I have had to reset the router to the able to access it.
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Jun 28, 2012
I have a Motorola SBG6580 wireless gateway/router and am happy with it in general. I had a 192.168.2.n subnet with old Linksys but I find that I cannot change the MOT from its pre-set 192.168.0.n net to the ..2.net because it conflicts with a "private LAN" in the same range. How do I change the provate lan to, for example, ..9.n so I can use the ...2.n net? I'm running with the ..0.n now, just fine, but, I VPN into office and primary net there is ..0.n and so is confusing with IP shortcuts/conflicts. how to make the change?
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Jun 1, 2011
here where I work we are having an issue with IP Address conflicts. We are not sure exactly why, though. We have only had it happen 2-3 times so far, but this has been over the past week or so, and we would like to get it resolved. Here is what is happening: Last week we were getting an "IP Address conflict" message on one of our computers. It had received 192.168.3.112 from our DCHP server, so we switched it to a static IP address up beyond our DHCP range. We then tried pinging the address with the conflict, but got nothing. We figured it was some device that had a static address, so on the DHCP server we reserved it to a non-existent mac address so it wouldn't hand that one out again. This wasn't a problem, since it was an isolated incident.
Since then we have tried periodically pinging 192.168.3.112 to see if there is actually a device using that address, but have gotten no replies. Since then we have had another one or two times where this has happened, but with different IP addresses. We went around and checked a couple of different wireless routers that we had deployed, but the DHCP had been disabled on all of them (but then again, the issue came up just recently, while the routers have been out there for months).
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May 18, 2011
I have recently started getting random 'Windows System Error- There is an IP conflict' blah blah blah messages on my PC, this only seems to happen when I also have the wireless switched on on my HTC Desire phone.I have done the usual checks and everything in the house, that is connecting to the wireless (2 phones and a laptop) is on a different IP address so as far as I can see there is no actual conflict.I have a Netgear WPN824v2 Router with the main PC connected to it. Sometimes it goes for ages without doing it or I can get one after the other, sometimes the PC drops it's internet connection altogether.
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Dec 23, 2010
Hooked up this router the other day to replace my old Linksys G - which has been bulletproof for 8 years. I am now wondering if I made a mistake with this unit.
I set up DDNS - after much trial and error with dyndns it now works fine.I tried to set up NTP time function - does not work. Then I set time manually. Of course on reboot it looses the time since there is no internal time function. So I need NTP.In the course of troubleshooting I turned off DDNS and behold the NTP time function now works. I turn DDNS back on and NTP does not work.
I see no logical connection between these two functions, yet the seem to interact (or not) somehow.When the NTP is not working, on reboot the time displayed in the router is the last time that I MANUALLY set the time, even though that is grayed out since I have (supposedly) activated NTP.
If I do NOTHING to NTP and uncheck DDNS, after reboot the time is correct.I tried many different NTP servers all with the same result.Looking back on-line, I see the NTP function has been a continual problem with some folks (maybe those using DDNS?) in earlier firmware. Come on DLINK don't you think it's time to get this fixed?
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May 2, 2012
I just found out that one of our 10 3750's has been assigned with an IP Address that is in conflict with a PC that has been in production long before this 3750 was deployed in our environment. Good thing it is servicing devices on a separate vlan. The conflict IP Address is assigned to the default vlan of the switch so we can connect to it from the core.If I change the IP Address of the switch, will it reboot and momentarily disconnect the devices connected to it?
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May 3, 2013
I m getting the below debug log and can not get IP from my ISP. It is static IP address and there is modem in bridge mode for the adsl line.
Below Conf and debug out put,interface GigabitEthernet0/1
no ip address
duplex auto
speed auto
pppoe enable group global
pppoe-client dial-pool-number 2
end
[Code]....
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Dec 12, 2011
We’ve recently installed a 5508 w LAN controller for my organization wireless network and each time devices connect to this wireless network they receive an ip conflict error. All devices conflict with the ip address of IP address 0.0.0.0 with mac address 00-00-00-00-00-00.
All devices event viewer has this TCP error: “The system detected an address conflict for IP address 0.0.0.0 with the system having network hardware address 00-00-00-00-00-00. Network operations on this system may be disrupted as a result.” We previously experienced the same ip conflict with 12000 w LAN network that he had used as proof of concept.
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Sep 6, 2011
I have two networks in same ip address sys 1 in 192.168.1.xxx sys 2 in 192.168.1.xxx where XXX = 0 to 254 i want to make a link between sys 1 and sys 2 without ip address conflict. is it possible to do so ??
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Oct 24, 2011
recently I have been getting slow internet and download speeds at a later time in the day, when there is 3 or 2 internet connections that show up in my connections. one being mine virgin broadband, another sky and Bthomehub, whenever these connections are up my download speed on steam goes from 1.1mb/s to 250kb/s and i get the message from windows saying' 'windows has detected ip conflict'' I can still access the internet play games online fine, but my download speed is really slow and sometimes internet is slow aswell
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Jun 17, 2012
This has been happening for a few months and I have had to reset the router every time and it usually works. I have 3 laptops, normally 2 are used and a roku streaming player connected to the tv. Both laptops are on windows 7 and sometimes the wifi suddenly stops working [sometimes only stops for some devices] even though i am still connected to the my router. Some times, a popup comes up that says that windows has detected an ip address conflict, so I think that that is the problem, but when I try to do ip/release, renew, it says that the media is disconnected to wireless network connection 2 even while i can access the internet.
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