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DHCP through router
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| mcdoud 2002-05-23, 4:06 pm |
| How does DHCP work through a router? I realize the router needs to be able to forward the requests (BOOTP forward). But this would usually indicate that the DHCP server is configuring clients for 2 subnets. I assume you need to set up 2 scopes with the addresses for the 2 subnets. Does DHCP automatically distribute these from the correct scope? Or is it controlled by using 2 NIC's in the DHCP server? | |
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| mcdoud 2002-05-24, 1:55 pm |
| ...but I was hoping for a simple explanation. I tried looking at the links/RFC's, but don't have time right now to take a "course" on that particular subject.
If anyone has a quick & simple answer, please let me know.
Again, thanks anyway!!! | |
| Bluerinse 2002-05-24, 6:25 pm |
| Okay...
quote:
or is it controlled by using 2 nics in the DHCP server
Well, I can say *no*, that is not how it's done but I can't add anything else, so I am also interested in this answer. I spent some time reading the various links and FAQs and came up with this as the closest thing to this threads question;
"One way to do this is to preconfigure each client with information about what group it belongs to. A DHCP feature designed for this is the "user class" option. To do this, the client software must allow the user class option to be preconfigured and the server software must support its use to control which pool a client's address is allocated from".
This leaves me with another question, what if the clients/server don't support the user class option?
Is this how it works or am I missing something, like the straight forward answer?
Pete | |
| UK_Boy_UK 2002-05-26, 4:54 am |
| I asked the same question a month or so ago and got some useful replies.
Take a look at item 23 on Zaraspook's link. As I understand it, the BOOTP router adds info about it's 'internal' address to the Discover packets. Therefore, when it gets to the DHCP server, it know which subnet it relates to.
So, you are quite correct that you need two scopes/address ranges, but there is no need for two NICs on the DHCP srv.
Class options are a bit of a red-herring. They don't relate to different scopes, they just relate to different scope OPTIONS within a scope. | |
| Bluerinse 2002-05-26, 5:06 pm |
| Thanks UK_Boy_UK, I now understand
Pete | |
| mcdoud 2002-05-27, 10:39 pm |
| Thanks all. That's kinda how I thought it might be.
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| mcdoud 2002-06-05, 2:23 pm |
| ...COOL! | |
| Bluerinse 2002-06-05, 6:36 pm |
| Thanks psnell,
even took the time to read Alicia Silverstone Discusses Basic ISDN 
I wasn't even that interested but she can teach me whatever she likes!!
Pete | |
| psnell 2002-06-05, 7:11 pm |
| quote:
even took the time to read Alicia Silverstone Discusses Basic ISDN. I wasn't even that interested but she can teach me whatever she likes!!
I felt the same way about Liz Hurley and the 2600 series routers  -- Pete | |
| chodan 2002-06-08, 8:24 pm |
| Routergod rocks
just wish he would update more with more
celebtech interviews .
As for fowarding DHCP requests, its done in the cisco world on a router using the IP helper address which listens for DHCP request broadcasts and fowards those to a DHCP server "whose address is supplied after the ip helper address command".
The DHCP server "if configured with the appropriate remote subnet scope" will send the IP config info to the appropriate subnet "the one from which the request was recieved" |
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