dhcpd and dhcrelay

[Chuck Anderson]

On Wed, Oct 01, 2008 at 10:23:11AM +0400, Elena Timoshkina wrote:
> > Why?  Where will you be relaying packets from/to if the packets are 
> > arriving at the dhcpd server already?
> Dhcrelay will work with other dhcpd server (
> dhcrelay_servers="10.97.5.2" ).

What VLAN or interface is 10.97.5.2 attached to?

> > It makes no sense to run dhcrelay with a single interface.  You need 
> > two interfaces that dhcrelay will relay the packets between.
> How can I determine two interfaces for dhcrelay? It will work in
> vlan667 (requests) and vlan667 (relay to server  10.97.5.2).
> It is possible?

So the server is on vlan667 and the clients are also on the same 
vlan667?  You don't need or want a relay at all in that case.

> >> But dhcrelay not binded in interface vlan667. How can I do it - to
> >> bind dhcrelay in address 10.97.7.18 only?
> 
> > dhcrelay doesn't bind to IP addresses, but rather physical interfaces.
> ok. how to bind it in vlan667 and not bind in vlan39 ?
> > This is because the DHCP protocol needs to handle broadcasts from 
> > unaddressed hosts (0.0.0.0 source address) and send to all-ones 
> > broadcast 255.255.255.255.
> yes, can dhcrelay listen only broadcasts in vlan667 (not vlan39 and
> others)?

dhcrelay -i <client-iface> -i <server-iface> 10.97.7.18

If client-iface is the same as server-iface, don't run dhcrelay at 
all.