At 01:52 PM 4/15/01, Michael Snyder wrote:
>I happen to be a ccnp and mcse. I get how ip helper-address works. Also
>work with microsoft dhcp servers.
>
>How do you setup a scope for a remote subnet, and how does the dhcp server
>know how to hand out the correct ip leases for a non-connected subnet?
>
>Does the dhcp server look at the source address of the interface of the
>forwarded helper-address packets? Then match up the correct scope with the
>router interface ip address?
The source MAC address is the router's address (assuming the packet only
went one hop), but the source IP address is 0.0.0.0, so that doesn't help.
What does help is that the DHCP packet has a GIAddr (Gateway IP Address)
field. The router that forwards the packet puts its own address in that
field. The router puts the address for the interface that the DHCP Discover
packet came in on. The remote DHCP server can figure out which scope it's
dealing with from that info. The GIAddr should be from the same subnet as
the requesting host.
Priscilla
>""Jason J. Roysdon"" wrote in message
>[EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > Here's a fun link explaining ip helper:
> > http://routergod.com/trinity/
> >
> > --
> > Jason Roysdon, CCNP+Security/CCDP, MCSE, CNA, Network+, A+
> > List email: [EMAIL PROTECTED]
> > Homepage: http://jason.artoo.net/
> >
> >
> >
> > ""Muhammed Khalilullah"" wrote in message
> > [EMAIL PROTECTED]">news:[EMAIL PROTECTED]...
> > > Actually, the IP helper command is placed on the
> > > interface that is recieving the broadcasts. Now you
> > > have to decide which router is supposed to recieve the
> > > broadcasts. But in usual case, Clients usually try to
> > > communcate with the PDC for authentication and other
> > > stuffs. So, i think it would work to configure ip
> > > helper-address w.x.y.z on the ethernet interface of
> > > router 1 only (where w.x.y.z is the ip address of your
> > > PDC, but if you have multiple PDCs then you have to
> > > give the directed-broadcast address and also have to
> > > use ip directed-broadcast command).
> > >
> > > I hope this will work
> > >
> > > Muhammad Khalilullah
> > > CCNP, MCSE
> > >
> > > --- David Eitel wrote:
> > > > I have two routers connected via serial point to
> > > > point link. Router 1 has
> > > > an ethernet segment with PDC info I want forwarded
> > > > to Router 2 ethernet
> > > > segment. No ip directed broadcast is configured on
> > > > all interfaces. I want
> > > > netbios traffic passed from one segment to the
> > > > other. I have placed an IP
> > > > helper-address statement on the ethernet interface
> > > > needing the help. Do I
> > > > need to use the ip helper-address on all interfaces
> > > > to the source ip
> > > > helper-address? Is the ip forward-protocol also
> > > > necessary? Any advice would
> > > > be greatly appreciated
> > > >
> > > > David Eitel
> > > > FAQ, list archives, and subscription info:
> > > > http://www.groupstudy.com/list/cisco.html
> > > > Report misconduct and Nondisclosure violations to
> > > [EMAIL PROTECTED]
> > >
> > >
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________________________
Priscilla Oppenheimer
http://www.priscilla.com
Message Posted at:
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