RE: Same Wire Different Vlans

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The thing is, if you're running proper VLANS, as you seem to be with a Cisco
6000 switch + MSFC, then the subnets are *not* all on the same wire. If you
don't have a ISL or 802.1q trunk connection from your DHCP server to the
switch then the server is (most likely) in one subnet. If you where running
a trunk connection you would have a multitude of logical interfaces for the
VLANs.

In the context of the ISC-DHCP server a "shared network" is where two or
more subnets are configured on the same interface, logical or physical. They
are declared "shared" so that the DHCP server knows it can hand out leases
from either subnet to booting hosts connected to that interface. VLANs do
not infer shared networks, so, you shouldn't be declaring your remote
subnets - beyond the router (MFSC) - as being shared along with the subnet
local to your server, they are, obviously, not on the same interface.

To summarize, get rid of the "shared network" declaration until you know for
sure you need it.

Regards Mike D.

-----Original Message-----
From: dhcp-server-bounce@xxxxxxx [mailto:dhcp-server-bounce@xxxxxxx]On
Behalf Of Patrick Nixon
Sent: Saturday, January 25, 2003 1:38 AM
To: dhcp-server@xxxxxxx
Subject: Re: Same Wire Different Vlans


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Have you configured your 'ip helper-address on the MSFC?

Each interface vlan## needs one pointing to the DHCP Server's IP.

--Pat

On Fri, 2003-01-24 at 14:21, Sean Murphy wrote:
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***
>
>
> I believe it is operating on the ethernet adapter.  here is the start up
of
> what it is currently doing it is similar but it is not using the same conf
> file so at least it will give out address to the 31 vlan.
>
> I get this same message but it has the shared-network name on it and fxp0
> is the network card on it.
>
> if you need the exact one I will have to change it during lunch
>
> thanks for your help
>
>
>
> thebe# dhcpd
> Internet Software Consortium DHCP Server V3.0pl2
> Copyright 1995-2003 Internet Software Consortium.
> All rights reserved.
> For info, please visit http://www.isc.org/products/DHCP
> Wrote 11 leases to leases file.
> Listening on BPF/fxp0/00:d0:b7:9d:90:79/172.31.0/16
> Sending on   BPF/fxp0/00:d0:b7:9d:90:79/172.31.0/16
> Sending on   Socket/fallback/fallback-net
>
>
> At 06:09 PM 1/24/2003 +0000, you wrote:
> >    *** From dhcp-server -- To unsubscribe, see the end of this message.
***
> >
> >
> >
> ><snip>
> >
> > > the first subnet it answers on and the server has the ip on that
networ=
> >k.
> > > =
> >
> > > the second it does not answer on.
> > > =
> >
> > > I think I need something in the conf file but I don't know what.
> >
> >I don't think so; I'm fairly sure that the problem is that the
> >DHCP daemon "thinks" that the interface is *not* an Ethernet
> >interface; the ordinary interface for the "native" VLAN is
> >Ethernet but the interfaces for the VLANs that appear on the
> >wire with VLAN tags are not Ethernets. I suspect the problem
> >is either FreeBSD or perhaps generic *BSD specific.
> >
> >-- =
> >
> >         David Pick
> >
> >
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>
> Sean Murphy
> Network Technician
> California Institute of the Arts
> Voice           661.253.7732
> Fax             661.254-4561
>                  smurphy@xxxxxxxxxxx
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