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TOPIC: DHCP Complications

DHCP Complications 8 years 2 months ago #27468

  • farles
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Hi, I'm new to the site and have some questions.

I've setup a Linux Terminal Server that uses PXE booting and DHCP. We are running a 3550 as our current DHCP server. All of our traffic was on VLAN1 so we created VLAN2 for the terminal server and its clients and didn't set a DHCP pool for vlan2. The problem is that the clients sometimes still get an IP from the 3550. Any idea's?
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Re: DHCP Complications 8 years 2 months ago #27476

  • S0lo
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Hi farles,

I understand from you that your PXE server (which is also your DHCP server for VLAN2) has been setup correctly with the write IP pool/gateway for VLAN2. And that the clients on VLAN2 receive and boot correctly with PXE. Only some clients some times receive IPs that belong to VLAN1. Is that what you meant?
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Ammar Muqaddas
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Re: DHCP Complications 8 years 2 months ago #27479

  • farles
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Yes, except that they do not receive IP's from Vlan1.

For example Vlan1 is 10.101.90.*
Vlan2 is 10.101.91.*

The clients will get an IP of 10.101.0.* and the default gateway is blank. When the clients get the IP from the Linux box they boot fine and don't have any problems.

I haven't configured the 3550 with any information about the Linux (DHCP) server, should I do some configuration to tell it to forward requests to it? Thanks
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Re: DHCP Complications 8 years 2 months ago #27480

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No need to configure the two DHCP services to know each other in any way.

First I'd make sure (recheck) that those problemed clients are connected to ports that are correctly assigned to VLAN2 on the 3550.

Second, Make sure that the DHCP pool on the 3550 is defined with the correct subnet mask (or range) for VLAN1. Your getting IPs of 10.101.0.*, Sounds like the the pool's mask is set to 255.255.0.0. It should be set to the same mask your using for VLAN1, otherwise the pool might cover both VLANs and the switch will wrongly issue IPs for both.

Hope that helps.
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Ammar Muqaddas
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Re: DHCP Complications 8 years 2 months ago #27489

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S0lo,
Thanks for your help. It looks like our network admin had setup a "master" pool and once I showed him your post he remembered that 10.101.0.0 was also defined there. He removed it and when a client is connected Vlan2 it boots perfectly. Thanks again.
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Re: DHCP Complications 8 years 2 months ago #27491

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Glad it worked!! :)
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Ammar Muqaddas
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