DHCP rocks, even on small networks.

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Postposted on Sun Jan 27, 2002 6:14 am

I myself uses DHCP on my home network... pretty small, only like 4 pcs, but peeps come over now and then for some lan gaming no need to assign ip to them before hand.

And anyway, if you setup your work group correctly you can look up the ip address using the computer's netbios name. No problem at all.

Another thing about DHCP is that, it will always try to assign the same ip back to the same machine when it comes on, as long as no one else is using it... So if you dont really format your systems often, the IPs doesnt change.
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Postposted on Sun Jan 27, 2002 6:16 am

Idiotic of me, but I clicked on new topic instead of reply. can some kind moderator kill this thread? I'm really sorry for my blunder.
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Postposted on Sun Jan 27, 2002 8:46 am

And anyway, if you setup your work group correctly you can look up the ip address using the computer's netbios name. No problem at all.


Not all of us are 100% Windows shops. Ever tried to manage a Unix box via SSH when you don't know the target IP address?!?

Another thing about DHCP is that, it will always try to assign the same ip back to the same machine when it comes on, as long as no one else is using it


Not true - most DHCP servers have no concept of a history. You will get the same IP address back under certain conditions, but the server certainly doesn't "remember" MAC addresses.

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Postposted on Sun Jan 27, 2002 10:31 pm

well, I would kill this thread, but now we've got a reply. And about that reply:
Bruce, a lot of dhcp servers most certainly DO remember MAC addresses. And not just Microsquish built ones either.
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Postposted on Mon Jan 28, 2002 1:17 am

If we're talking about the same thing: yes, they remember MAC addresses - if you tell them to (ie, create a MAC/IP address mapping). But they won't do it on their own. Unless I've missed something....?

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Postposted on Tue Jan 29, 2002 12:51 pm

well, maybe we should make sure we're on the same page. I've only ever worked with basic dhcp daemons running on unix, and I've never tweaked them to do anything fancy, yet they always seem to remember a MAC address and give that MAC address the same IP address. This may be a function of the dhcp client, just asking for an IP address it's received before, but I don't think so, since I regularly get the same IP address from my home dhcp server every time I reload Windows on my gaming machine. Now, you certainly can set dhcp servers to pre-assign a certain IP address to a particular MAC address, and for that you would have to explicitly tell it to do it that way, but I don't think that's what Technie was referring to.
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Postposted on Wed Jan 30, 2002 8:12 am

One thing that may be happening with the Windows box is that it may not issue a DHCP 'release' on reboot - if that's the case, when it issues a DHCP 'request', the DHCP server will still have the lease in it's table (issued to the same MAC address). It will simply renew that lease, and you'll get the same IP address every time.

Just a thought - anyone else have any ideas on this? Do all versions of Windows not send a DHCP release on shutdown or reboot?

Bruce

<font size=-1>[ This Message was edited by: Bruce on 2002-01-30 07:15 ]</font>
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Postposted on Wed Jan 30, 2002 9:53 am

I think you're right. I don't think Windows sends a release...also if your board supports Wake-On-Lan then you will still have a link to the DHCP server. I know this is the case on my Linksys router. The four comps that support WOL still show a link even with the power off and the crappy PII that doesn't have WOL has no link with the power off. I could be wrong about this though. Just my .02 Canadian.
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Postposted on Wed Jan 30, 2002 10:59 am

Windows does send the release if there is a clean shutdown (ie not crash or reset). Most dhcp server in their basic config (new version) will send the same ip adress to the same mac even if the lease is expired. Wake on lan will not keep the dhcp adress. Wake on lan simply keep the link up so you can boot the computer from remote using a magic packet.
Also dhcp is easier for lan and thing like these because you have less chances of having duplicates ip adress in you network.
As for unix using ssh, you could use dhcp and make a reservation. It would send always the same ip to that computer. You could also set the dhcp to always give the same ip to the same mac. Or you could use dynamic dns and configure the dhcp to update the dnc so you would just have to enter the dns name and it would connect to the correct server.

<font size=-1>[ This Message was edited by: Nuclear on 2002-01-30 10:00 ]</font>
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