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TOPIC: two dhcp servers clashing on thesame LAN

two dhcp servers clashing on thesame LAN 8 years 1 month ago #28000

  • sose
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I have a LAN of 20 sys connecting wirelessly through a linksys router - model WRT150N and it is serving as the dhcp server.
i changed my ISP and they gave me a modem that is dhcp enabled and it is sort of clashing with my existing wireless linksys dhcp server, so connection time out from time to time

All sys run on window xp with dlink wireless LAN card. I got a 3com switch and connected it with a straight cable to the modem and distributed to other clients via cable , discarding the linksys router. though connection still time out but has seriously minimized

can I still use my linksys router but not as dhcp server on the network

secondly when I ping my dns server with my ISP ,it time out but i can still browse other website at thesame time . i know the dns server is just number to name conversion.

any general observation

thanks
sose
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Re: two dhcp servers clashing on thesame LAN 8 years 1 month ago #28001

  • ZiPPy
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Heya sose,

You definitely want to disable DHCP on your modem that was provided from your ISP. Whenever you add a device on a network that already has DHCP enabled, your going to face some serious conflicts. Login to your modem directly and disable DHCP. It sounds like the modem your ISP gave you would have other options too. I suggest disabling all other options and just keep the device as a standard modem. Let your Linksy's router do all the work.


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ZiPPy
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Re: two dhcp servers clashing on thesame LAN 8 years 1 month ago #28002

  • sose
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as a client I cant log into my modem except i have clearance from my ISP- that is formalities but i will try them

the inconvenience i s that now i have connected a switch and I am browsing via cable so the modem is still the dhcp server
sose
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Re: two dhcp servers clashing on thesame LAN 8 years 1 month ago #28006

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Really? They won't let you login to your own modem? They are pretty strict if that's the case.

You need to power down any equipment that requires an IP from the DHCP server. If you are able to login to your modem, disable the DHCP and power up all equipment. All IP devices will look to your DHCP on the Linksy's and obtain an IP.


ZiPPy
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Re: two dhcp servers clashing on thesame LAN 8 years 1 month ago #28012

  • S0lo
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I agree with ZiPPy that two DHCPs for the same LAN range can cause trouble (unless configured properly).

Alternatively, If you can't disable DHCP on the modem. And if both your modem and the linksys have extra ports. You could connect them together (Or have you already done that?) then disable DHCP on the linksys. If I'm not mistaken, this way your linksys will work as a simple switch with one wireless port. The modem will accept DHCP traffic through your linksys and at the same time you use the wireless feature of the linksys.
Studying CCNP...

Ammar Muqaddas
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Re: two dhcp servers clashing on thesame LAN 8 years 1 month ago #28023

  • sose
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solo
what do you mean by the modem having one wireless port.

The modem will accept DHCP traffic through your linksys and at the same time you use the wireless feature of the linksys.


rather I think it is the linksys that will accept dhcp traffic from the modem


Also I tried disabling dhcp server on the linksys which immediately cut me off the wireless router. I cant quite figure out the first config on the router which has an option of static or dhcp which is different from the option of starting the dhcp server .

initially I thought if I connect my straight cable to the wireless router from the modem not to the internet port the it will only serve as a switch which will just boadcast wireless serviceservice
sose
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