[nsp] dsl/dhcp question

[Siva Valliappan]

Hi Charles,

   this is definitely possible.  you will need to enable option 82
support on the router side.  what this does is that it fills in additional
fields in the DHCP Discover packet that is proxied to the DHCP server.
The server can then use the additional information to issue the same
address if desired.  however, you will need to make changes to the
DHCP server as well to make this happen.

for the router overview:

http://www.cisco.com/univercd/cc/td/doc/product/software/ios122/122newft/122t/122t2/ftrbeo82.htm

this idea came from the cable world actually.  since the cable CMTSes were
the first to make use of option 82 support to control the addresses given
out to PCs behind cable modems.  so i believe any DHCP server that is
used to provision cable modems, will support this.  e.g. CNR.  if you are
using a Cisco DHCP server, a case with the TAC might help you get started.

unfortunately i don't have a handy config sample for the DHCP server side.
hope this helps you get started.

cheers
.siva

On Sat, 28 Jun 2003, Charles Sprickman wrote:

> Hello,
>
> I don't think the BBA list is big enough yet, so I thought I'd ask here.
>
> Some time ago when I first started looking at moving everyone from IRB to
> RBE, I could have sworn I found a doc on CCO that had some nifty tricks
> with RBE and DHCP.  Namely, that each user/subinterface could be tied to a
> particular IP address.  ie: if a dhcp request came in on "atm 2/0.1999",
> the dhcp server would always try to give out the same fixed IP.
>
> Did I imagine that?  I'm knee-deep in CCO and not seeing it.
>
> The goal is to auto-configure people who want static addresses without
> knowing their mac address in advance.
>
> Anyone doing something similar and willing to share?  It looks like this
> "option 82" thing can tell an external dhcp server something about where
> the request came from, but I'm not sure which dhcp server support this.
>
> Thanks,
>
> Charles
>
> --
> Charles Sprickman
> spork at inch.com
>
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