Re: DHCP Option 82 And Classes In Depth Understanding

Was there an answer to this? Just wanting to make sure I did not miss it ...

On Mon, Oct 26, 2009 at 5:19 AM, karim jamali <karim.jamali_at_gmail.com>wrote:

> Dear Experts,
>
> I was reading through the DOC CD about DHCP Option 82, and the ability to
> create DHCP classes. Please correct me if I am wrong with the following
> statements:
>
> 1)DHCP request is a broadcasted on the LAN segment and it is up to the
> gateway (giaddress field) to convert it to a unicast ip address (relaying
> the information) when the ip helper-address is used pointing towards the
> server.
>
> 2)Based on this giaddress,the server knows that the client from a certain
> subnet requested an ip address, thus it provides it with an ip address from
> that subnet.
>
> 2)Option 82 gives another method to segregate clients other than the subnet
> in which users reside, i.e. having two hosts on a common vlan (subnet) it
> is
> still possible to give each host an ip address from a different range which
> corresponds to a different option 82 (hexadecimal value).This can happen by
> defining a common pool and dividing the pool into classes, where each class
> is matched by the option 82 value and corresponds to a different range of
> ip
> addresses.
>
> 3)The server will examine the relay agent information, and check it against
> the list of classes relay-information to find a match. This match will
> correspond to a certain class and a certain range of ip addresses within
> the
> pool.
>
> The part I don't understand is : Two users are on VLAN X for instance, I
> want to give each an ip address from a different range. I create two
> different classes each corresponding to a different range of ip addresses
> and to two different relay-information. Does the relay-information match
> the
> client-id?How is the client associated with a class?
>
>
> An example taken from DOC CD:
>
> Defines the DHCP classes and relay information patterns
>
> ip dhcp class CLASS1
>
> relay agent information
>
> relay-information hex 01030a0b0c02050000000123
>
> relay-information hex 01030a0b0c02*
>
> relay-information hex 01030a0b0c02050000000000 bitmask
> 0000000000000000000000FF
>
>
> ip dhcp class CLASS2
>
> relay agent information
>
> relay-information hex 01040102030402020102
>
> relay-information hex 01040101030402020102
>
>
> ip dhcp class CLASS3
>
> relay agent information
>
>
> ! Associates the DHCP pool with DHCP classes
>
> ip dhcp pool ABC
>
> network 10.0.20.0 255.255.255.0
>
> class CLASS1
>
> address range 10.0.20.1 10.0.20.100
>
> class CLASS2
>
> address range 10.0.20.101 10.0.20.200
>
> class CLASS3
>
> address range 10.0.20.201 10.0.20.254
>
>
>
> Thank You
>
> Best Regards,
>
>
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