[nsp] dsl/dhcp question

[Huw Jones (hjones)]

Hi Charles,

This config won't work, it appears to be an older document on CCO.  To
work you firstly need to be running RBE with an ip unnumbered interface,
then you can configure either a dhcp helper address on the interface,
when the dhcp request is serviced a route should be automatically
inserted in the routing table to the client.  This should also work if
you use a dhcp server on the router as well.

Cheers
Huw

 



> -----Original Message-----
> From: Charles Sprickman [mailto:spork at inch.com] 
> Sent: 07 July 2003 06:35
> To: cisco-nsp at puck.nether.net
> Subject: Re: [nsp] dsl/dhcp question
> 
> 
> Hi all,
> 
> A few more  questions on DHCP + RBE to take care of things 
> while I get the fancy option 82 business and ISC-DHCP playing 
> nice together...
> 
> Looking at the RBE docs (which seem to have gotten slimmer 
> since the 6400 was EOL'd), there are some examples like this:
> 
> http://www.cisco.com/warp/customer/794/827rfc_6400rbe_2.html
> 
> In this example, there is a 675 in bridge mode and a pc setup 
> as a dhcp client.  The pvc terminates on a 6400, but there is 
> no dhcp config on the 6400; just a static route set to the 
> pvc.  What gives?  Is this just a mistake, or am I missing 
> something?  From what I see, this wouldn't work.
> 
> Next...  With RBE and the IOS dhcp server, if I enable dhcp, 
> does the server (not relay-agent) automatically add a static 
> route to the atm subinterface for the duration of the lease?
> 
> Lastly, I've been trying to dig up as much info as I can on 
> RBE and it seems like there's less on CCO than I remember.  
> Should I be looking anywhere beyond this:
> 
> http://www.cisco.com/cgi-bin/Support/browse/psp_view.pl?p=Inte
rnetworking:RBE__Route-> Bridged_Encapsulation&viewall=true
> 
> I also was reading this, is there something like it that is updated?
> 
> http://www.cisco.com/warp/customer/794/routed_bridged_encap.html
> 
> Thanks,
> 
> Charles
> 
> On Mon, 30 Jun 2003, Siva Valliappan wrote:
> 
> > 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/ios122/122new
> > ft/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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> > > http://puck.nether.net/mailman/listinfo/cisco-nsp
> > > archive at http://puck.nether.net/pipermail/cisco-nsp/
> > >
> >
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