Good Article on DHCP

kryolla

Everyone know that configuring a router as a DHCP server on the same subnet is easy. Hopefully this thread will make it easy for people like me that was not clear on how to set up a central DHCP server to serve multiple subnets. The important part of the DHCP header is the giaddr field which is the address of the Interface of ip helper address command

http://articles.techrepublic.com.com/5100-6345_11-5034551.html?tag=rbxccnbtr1

Here is from Cisco Docs

DHCP defines a process by which the DHCP Server knows the IP subnet in which the DHCP client resides, and it can assign an IP address from a pool of valid IP addresses in that subnet.

The DHCP Server identifies which DHCP address pool to use to service a client request as follows:

•If the client is not directly connected (the giaddr field of the DHCPDISCOVER broadcast message is non-zero), the DHCP Server matches the DHCPDISCOVER with a DHCP pool that has the subnet that contains the IP address in the giaddr field.

•If the client is directly connected (the giaddr field is zero), the DHCP Server matches the DHCPDISCOVER with DHCP pool(s) that contain the subnet(s) configured on the receiving interface. If the interface has secondary IP addresses, the subnets associated with the secondary IP addresses are examined for possible allocation only after the subnet associated with the primary IP address (on the interface) is exhausted.

dynamik

This one is ok too. I kid, I kid.

Nice link. Thanks for sharing.

kryolla

edit

sprkymrk

kryolla wrote:

If you been in the field, what they teach in class is different than what goes on in the field.

Not always. Depends on the class, the instructor, the student, etc.

kryolla

sprkymrk wrote:

kryolla wrote:

If you been in the field, what they teach in class is different than what goes on in the field.

Not always. Depends on the class, the instructor, the student, etc.

just speaking from my experience

dtlokee

<sarcasm>
Yeah because often in the field your focus is so narrow when you get into the classroom it covers way more than you need in the field
</sarcasm>


Of course looking stuff up on google isn't going to be an exam objective either.

dynamik

dtlokee wrote:

Of course looking stuff up on google isn't going to be an exam objective either.

Google+

kryolla

edit

dtlokee

One of the side effects of studying for the CCIE lab is I now find ways to come up with 10 oddball solutions to a simple problem.

sprkymrk

dtlokee wrote:

One of the side effects of studying for the CCIE lab is I now find ways to come up with 10 oddball solutions to a simple problem.

And you could come up with 1,435,237 more in .0435 seconds if you had your Google+ cert. :P

AlanJames

good read. ip helper-address is your friend when using a windows DHCP server,

sir_creamy_

kryolla wrote:

RFC are good for theory but how do you apply that theory in the real world.

Try to write a simple FTP client/server from scratch without consulting the corresponding RFC. How can you implement a protocol if you don't know its specification?

Developers bathe themselves in RFCs.