dhcp ( & cisco related ) question

Petre Bandac petre at kgb.ro
Tue Aug 8 20:00:27 UTC 2006


On Tue, 08 Aug 2006 14:46:32 -0500 Anno Domini, the honourable Ken
Roberts wrote using one of his keyboards:
> On Tue, 2006-08-08 at 14:36, Petre Bandac wrote:
> > > The pertinent configuration for the Cisco gear (assuming a 3550
> > > layer 3 switch) is:
> > > ip dhcp relay information option
> > > no ip dhcp relay information check
> > > 
> > > and then, for each VLAN:
> > > ip helper-address 192.168.3.12
> > > ip helper-address 192.168.3.13
> > > 
> > > For your dhcp configuration, create your subnets the way you would
> > > think.  The router will send along enough information so that
> > > dhcpd can figure out which subnet you're on.
> > 
> > ok here too, with the observation that the 3560 router will act as a
> > gateway with the ip put on the vlan; however, this observation
> > becomes a nonsense if the interface which relays does not have to
> > be "unnumbered"
> 
> 
> I don't understand what you're saying here.  I'm not an expert, but I
> did get my Cisco gear to work with dhcpd.  You're suggesting a DHCP
> request for which there is no defined network information?  Assuming
> your router is configured, how would that even work?
> 
> My 3550 stack acts as the router for each VLAN.  The way I understand
> it, for each VLAN where the switch acts as a router, the router must
> have at least one IP address on that VLAN.

yes, that is my configuration too; and can I avoid the dhcp linux box
behind the cisco to have one ip from all vlans it serves ?

> Is this a correct statement?  Or maybe I completely missed what you're
> trying to say?
> 

sorry for my ambiguous english ;)

> 
> 


-- 

Petre Bandac

Network Scientist

-
petre at kgb.ro



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